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View Full Version : dial calipers vs micrometers - do I need both?



k2man
09-01-2014, 11:57 AM
I have a couple of dial calipers - a digital and an older dial. As a kid, my dad had a couple of C shaped micrometers that I'd use some -don't know where these went to (brother probably gave away in a garage sale when he passed - like he did with my fiberglass canoe that my other brother, dad and I built.... grrrr... that's another story).

I'm buying my first lathe. Want a milling machine also, but may have to wait, but I do some machining with my drill press and xy table.

I'm building small parts - prototypes - usually less than 6" in any dimension.

My question is, do I need micrometers - or will dial calipers do the same job?

jlevie
09-01-2014, 12:02 PM
Compared to micrometers, calipers are "guess-o-meters". For accurate work, you get close with the calipers and finish with the micrometers.

goose
09-01-2014, 12:06 PM
No, they will not do the same job.

You may (most likely for sure eventually) need a micrometer depending on the work you plan on doing.

I'd recommend a good quality digital micrometer, such as Mititoyo. 0 to 1 inch. If you can find one used at a good price, great. Otherwise buy new.

achtanelion
09-01-2014, 12:07 PM
It all depends on the accuracy you need. That being said, I thing of my caliper so as being within 5 thou, and mikes as being within a thou. If you need fits between multiple parts, 5 thou stacks pretty quickly.

macona
09-01-2014, 12:07 PM
The larger you get the easier it is to make a mistake with calipers. Get micrometers, especially if you are making parts for someone else.

Arthur.Marks
09-01-2014, 12:13 PM
A general rule of thumb is dial calipers are accurate to +/- 0.001" (one 'thou' ) and micrometers are accurate to +/- 0.0001" ( one 'tenth' ). That is under ideal situations and experienced use. For a lot of work, dial calipers are very precise in comparison to the tolerance needed. For other work, 0.0005" ( five 'tenths' ) is the difference between success and failure. Machining a shaft to fit a ball bearing would be a typical task where that might be the case.

Tony Ennis
09-01-2014, 12:20 PM
Arthur, I think you have too many zeroes. one thou is .001.

Arthur.Marks
09-01-2014, 12:23 PM
Arthur, I think you have too many zeroes. one thou is .001.
Ha! I am an idiot!! :p Both had an extra zero. Doh! (corrected)

KJ1I
09-01-2014, 12:25 PM
achtanelion hit it on the head. It depends on what you are doing and how precise you need to be. I have both, but use the calipers 10 times as much as the micrometer. Most of my work just doesn't need to be that accurate. Get the calipers first, then, when you define the need, get the micrometer.

And as a side Arthur is right, but his typing is off. One thou (one thousandth of an inch) is 0.001, a "tenth" is 0.0001. Arthur knows this, his fingers just missed.

mattthemuppet
09-01-2014, 12:26 PM
I would get both, especially if you're doing any inside diameter work as calipers are particularly crap at that in my experience. The accuracy and fit of my work improved many fold when I got a set of micrometers and telescopic bore gauges. Now I use the caliper for rough measurements and the micrometers from the last few mm to the final dimension.

Richard P Wilson
09-01-2014, 12:39 PM
A decent 8" digital caliper will measure outside diameter, bore size and depth, all in one tool. With micrometers, outside diameter, bore and depth all need different tools, and usually each one only has a limited range, so for example I've got a 0-1", 1"-2" and 2"-6" micrometer. By the time you have repeated for bore and depth measurement, you've got a whole drawerfull of micrometers to do the same work as one digital calliper. OK, most guys reckon to use a calliper if the work doesn't need better accuracy than +/- .005", and a mike for anything better than this. IMHO, both callipers and micrometers need to be used with care and 'feel' if they are to give the best results. To be honest, the majority of home shop work doesn't need better than a good calliper can do if used carefully . I use the calliper for 90% of my work. Yes I've got all the mikes now, but thats after about 40 years. If you are starting out, go for the best digital calliper you can afford, and don't let it get knocked about or dropped on the floor. We used to use Starret vernier callipers, and they were really good, but my eyesight isn't up to that any more.

Richard

justanengineer
09-01-2014, 12:48 PM
The rule of thumb for measurement - measurements are only considered accurate to 3x the smallest division of the tool used. A caliper measures to .001, therefore its only considered accurate to .003 or +/- .0015. A vernier mic measures to .0001, therefore its accurate to .0003 or +/-.00015.

Make sure you get mics that have a vernier scale on the barrel to measure to .0001. Not all mics have it.

ahidley
09-01-2014, 01:56 PM
I use a 6 inch dial caliper 99.9 % of the time. They work for depth, inside, and outside. I've compared my. $14 Chinese cailpers to mitotoyo micrometers and they read the same. If you need more accuracy than a thousandth then HEAT is going to make a bigger difference than dial calipercaliper vs mic. Now if your measuring a six inch OD then a Mic is needed because it will span across the diameter. The dial calipers jaws are too short. Now if you buy 0-6 mics you need six tools. Mics only read in increments of one inch. Now what I speak of are dial calipers not vineer and steel framed not plastic or composite.

Forrest Addy
09-01-2014, 02:50 PM
When I was a boy I went with my dad to visit one of his old friends who was a fly fisherman. I got to playing with his tacklebox a, complex home made affair with many trays and tills and compartments each dedicated to different kinds of flies, weights, leaders, spoons maybe hundreds of different complex and colorful things and it all folded up about the size of a thick brief case. I was good about looking at things, being careful, and putting things back so I got to spend Dad's whole visit snooping in that miraculous taclebox. To my seven year old's eye, opening that box was like a discovering a new world, a place of intricate wonder. It's still one of my delights of recollection

Precision measurement is much like the tackle box to the enthusiastic noob: a whole new world of marvels. For most us, precision measurement starts with a micrometer. A dial caliper in good condition is a close second. Precision measurement branches of into a huge array of equipment and technique. but in the small scale home shop you can make do with simple equipment often at low cost if you are a good shopper.

Someone suggested a Mitutoyo digital micrometer which is a hell of a fine tool but expensive if bought new for a guy with a limited budget. Whatever your budget you probably want to maximize the bang for the buck. You will be urged to buy American but be tempted by the prices of the import equipment. Some regard a precision tool as a life investment, an heirloom whereas it's actually a functional tool and like any tool it's designed to accomplish a task you cannot do bare-handed. So buy a tool and put it to work while respecting its sensitivities.

My suggestion is to keep an open mind and study your needs and resources. If you desire to make prototype parts for your own use, a dial caliper will work fine for most everything you wish to measure. But you have to understand its limitations. Whatever the faithful may say of their personal dial calipers they are not as accurate as a micrometer but you need six micrometers, a depth mike set, and a set of telescope gages to cover the range of one dial caliper. Keep that dilemma in mind. Sonetime you need that accuracy.

I got to arguing with a friend one day about the merits etc so we had a "measure-off" where his wife (no slouch) assembled and taped the numbers of a few gage block stacks. He measured with hs dial calipers and I with my Polish mikes. The bet was sum of the error and lowest won. The prize was dinner. I won of course but my friend was crestfallen. Now he hated his dial caliper, it let him down. Place not your faith...

Sooner or later you will want to work with sleeve and ball bearings. There are people who say they can use their dial calipers to the tolerances for ball bearings but I can't do it. I need greater precision and reliabiity than I can get with a dial (or digital) caliper for bearing fits.

Which is a long way to say that a dial caliper will get you started and it may be all you need for a few years.

Caveat: a dial caliper will serve you well PROVIDED you keep it clean. It works with a rack and pinion. As you move the jaw along the fine toothed rack meshes with a pinion connected to the dial hand. The rack tooth spaces are a series of little dirt traps. The Achilles heel of a dial caliper is getting a speck in the rack and having the little gear jump a tooth. Suddenly the dial reads 0.025 with the jaws tight together. You then have to fiddle around, clean the rack, use the little re-setting gizmo to re-set the little gear and you've lost an hour. PITA. Keep it in the case and the case closed except when you use it.

Later as your skills improve and your need for greater precision becomes manifest you will wish to move up to micrometers and the stuff you need to employ them.

In the meantime, keep your eyes open and your tool budget handy for good used (or new) tools. Beware of junkers and the really cheap imports. Some time spent scrounging the catalogs, pawn shops, swap meets, and supply houses will be educational from the start. Bargains are like girl friends and busses: you may miss a good one but another just as good will come along sooner or later.

Don Roberts turned me on to a wonderful book on precision measurement. It's one of those survey books, capturing the state of the art at the date of writing.

"Fundamentals of Dinensional Metrology" by Ted Busch. IBSN 0-8273-0193-6

http://www.abebooks.com/book-search/isbn/0827301936/soft-cover/page-1/

It's far more advanced than needed by the average home shop owner but the first 10 chapter are applicable and the later ones interesting and challenging. It may tempt an enthusiast to round up exotic and highly refined one trick pony high precision measuring equipment but to what purpose? Read the book and marvel but in the end, be practical. In all my 50+ years of diversified experience in the trade where I've worked to very close tolerances and used the most refined (of the day) open shop measuring apparatus, I never needed 3/4 of the stuff covered in this book.

Old Hat
09-01-2014, 03:43 PM
The only point I can make without being redundant is ........
Why even consider a dial-caliper?

Digital calipers have been around longer than the internet, they're affordable, reliable,
and don't have the issues a dial has.

Your needs dictate the choice, but I'd leave dial-calipers where they belong,
in the history books on tooling evolution.

I need to be flexible, mobile sometimes, and often I'm measuring things
others made, as much as what I'm making.

I own no dial calipers, plenty of mics, but my heavy use tools are all calipers.
6" 8" 12" 40" in verniers and digitals, a few I've removed the depth rods from,
so I can be where I need to be, and not wish I'd brought more weapons.

TN Pat
09-01-2014, 03:57 PM
I concur with Old Hat... while aesthetically I prefer a dial caliper, the main reason is just aesthetic and so I can feel as if I'm achieving greater accuracy than I am. Measuring between the lines on a dial caliper is really, in almost any case, a fruitless pursuit when it boils down to reality. Mechanically - well, there is more to a dial caliper. A gear and rack, and space for dirt and chips to get in... whereas digital calipers are, in higher grades, coolant-proof and dust-proof to any specific degree.

But I do have one pair of calipers that I trust to at least .002. +/- .001. My Mitutoyo Absolutes, 6". $155 from Enco. Every where I check with gage blocks, it reads either dead on or towards the end of the range off by a half-thou. Even for ID's - the few times I've had to check an ID with a telescoping gage, measuring it with a mic gives the same reading as the ID jaws on the Mits within a half-thou.

So, to start off - I would get those. Mitutoyo Absolute calipers, 6". They last a long time, as well. If mine died or got wrecked, I'd get the exact same pair.

As to the question, caliper vs. micrometer - get at least a good pair of calipers. Then, figure out the most common size range you will be machining where you have tolerances of +/- .001 or tighter. If you machine a lot of pieces with a dimension of between 3 and 4 inches, but said dimension(s) only has(have) a tolerance of +/- .005, don't worry about a 3 to 4 mic.

For my case, at home, I only have a 6" lathe, limited in swing to begin with. Very, very seldom do I have a tolerance of tighter than +/- .005 on lengths. But diameters, I do have tight fits, for slips and presses - but, I rarely turn larger than 1" pieces. Therefore, at home, I only have a single outside micrometer, a 0 - 1", graduated in .0001. It is a Fowler, Chicom import, but it checks within .0001 at every place I check it.

Old Hat
09-01-2014, 04:03 PM
My 6". Mitutoyo Absolute caliper has been with me for ? 7years? or so.
Bought two for a good price on one of those two day sales.
The spare is still waiting to be used. 'Ol #1 has had a ruff life and is still go'n strong.

Rich Carlstedt
09-01-2014, 04:40 PM
The only point I can make without being redundant is ........
Why even consider a dial-caliper?...........

Well, for one they still work in low light conditions, and two, you don't need battery's

They also are visually faster when comparing two or three sizes at the same time, and
when doing a bore it is easier to follow a dial "movement" than a readout when looking for the true bore size

I am not saying that digital Calipers are any less, just that when you have a large toolbox, you have more options.
Never discount a lowly tool. That's why the old machinists had drawers of tools--because they never knew what to run into
and sometimes the lowly tool works---sort of like using a screwdriver instead of a miniature pry bar .

Rich

SGW
09-01-2014, 05:41 PM
When I was getting started, I had a 0-1" micrometer and a 0-6" vernier caliper. My eyes were better then. :D Today I'd get a dial or digital caliper.

The point was, for what I was doing, the 1" micrometer handled nearly all the real precision needs. The caliper was okay for measuring larger stuff when the occasion demanded it.
Over time I picked up a 1"-2" mike, then as I ran across them for cheap at sales, a 2-3" and a 3-4". I hardly ever use the larger ones, but the 0-1" micrometer gets a constant workout. If 'twere me I would buy a tenth-reading carbde-faced new Starrett 0-1" mike, and look for deals on others.

ahidley
09-01-2014, 06:04 PM
My shop is not heated . In the winter it might be 0 F there. When that happenes every little watch battery is dead. So I stick with dial calipers vs battery powered digital

PStechPaul
09-01-2014, 06:14 PM
I had mentioned in another thread that I have two dial calipers: one plastic which reads to 0.01", and another that reads to 0.001". The plastic one is handy for rough measurements and for electronic items (like batteries). I also have plastic digital calipers with 0.01" and 0.1 mm precision. They are OK for rough measurement and are often fine for larger dimensions that don't need better accuracy. I have two older (better) Harbor Freight digital calipers, one of which is non-functional, and the other I had to take apart and clean so it now works OK. And a newer HF (same model number 47257) but obviously inferior and different, with a white linear scale. It was only $10 and is OK for quick rough measurements, and I keep it in the shop where I might worry about damaging my better instruments.

But I also have my father's Starrett micrometer, which is far more accurate than the calipers, and that is what I trust for anything needing 0.001" accuracy. It doesn't have a vernier but I can interpolate to within about 0.00025".

As the resolution and accuracy increase, it also becomes an issue of measuring technique. It is important to make sure the jaws are clean, and also check for zero. If a part has a taper or is out of round, it can be difficult to get a good reading. The jaws must fit on parallel surfaces. The pressure used when measuring a part is also important. My micrometer has a friction clutch which assures the same amount of torque will be applied for every measurement. None of my calipers has this feature, so it important to use the same pressure on the adjusting knob. When measuring work while clamped in a machine, it is often difficult to get a good angle on it, so some calipers have a "hold" feature that is handy. But you can also lock the jaws when you take the measurement and then carefully remove the calipers to read them. You can also preset the jaws to the desired width and use them as a gauge. And perhaps a better way to measure round work in a lathe is to use "dividers" (also sometimes called calipers) with inside or outside tips, which can be preset to the desired measurement, and can more easily reach into features like grooves.

http://www.equipmenttooling.com/tooling/867629/1/starrett-4.html
http://www.jpnnxt.com/inspection-gauges/lathe-dividers-measure.html

brian Rupnow
09-01-2014, 08:10 PM
It depends on whether you want to be close or want to be accurate. Most of the things I build are for model i.c. engines. The required accuracy is more than can be achieved with calipers, either digital or analog. Ironically, I do most of my "marking out" with calipers. However, this is only to give me a visual reference. The actual work is done on the mill using an edge finder and the dials. For turning shafts and boring bushings, you need the accuracy of a micrometer.---Brian

vpt
09-01-2014, 08:40 PM
I loved my digital mitutoyo caliper that I have used for 15+ years now. I used them today again even though they are worn. I will be getting another to replace it, it is pretty much all I use for machining measurements.

A.K. Boomer
09-01-2014, 09:09 PM
everybody's got their two cents and that's ok --- but as far as calipers only being good for + or - .005" I would have to say if that's the case then you need to toss them and get a set of high quality 18.00 chinese ones:rolleyes:

that's what mine are and I have gotten so used to their accuracy that I would give them at least a + or - .001 reading --- I say that because they actually have a .0005" scale on them as well, and when they were new I could test and trust it about 9 times out of ten to be within that range,,, many of the guys who are claiming good results as well will tell you one thing, get a "feel" for them...

so ----- depends what you want to do but im sure just calipers will most likely be perfectly fine for you when just starting out,,, I did not own any mics for about three years,,, and then? I would say I can get + or - .0002" consistently - but that's getting to the point where you want to be careful your parts not aluminum and your not holding on to them for too long whilst measuring it... really think you need mics to start off with now? again what are you going to be building?

your already entering into a world of accuracy your not going to be very used too just in the calipers alone... so why not forgo the time consuming PITA slow response of using a mic if you don't really need too...

danlb
09-01-2014, 09:12 PM
I might have missed it, but I don't think anyone mentioned the area where dial calipers shine. They are very good at doing comparative measurements.

I can compare two parts quite accurately if I use a dial caliper with 1/1000 divisions. With the dial caliper you can see the relative position of the needle between the markings. I can tell if the needle falls at the same spot when measuring both parts.

The reason it's accurate in this use is that the gear will be in the same spot on the rack and the same tooth of the gear will be in mesh. The human eye is pretty good at determining if a needle lines up exactly on a line.

With a digital that reads to .001 with an accuracy of .005, you never know if the reading of .001 means .00124 or .00076.

Dial VS digital was driven home today when I used a digital caliper style DRO on my mill. Looking at the old fashioned hand wheel dial I could turn it 1 degree and move the quill a minute amount. Using the DRO I was limited to .0005 steps. I was trying to sneak up on a previous cut so that there would be no step. The dial turned out to be a better tool, even though the DRO measured the actual movement of the quill and the dial measured turns of a gear that moved the quill.

Dan

_Paul_
09-01-2014, 09:56 PM
Well, for one they still work in low light conditions, and two, you don't need battery's

They also are visually faster when comparing two or three sizes at the same time, and
when doing a bore it is easier to follow a dial "movement" than a readout when looking for the true bore size

+1

Paul

Old Hat
09-01-2014, 11:57 PM
The human eye is pretty good at determining if a needle lines up exactly on a line.



As in vernier scale, As in the reader on any glass scale in any CNC.
Can you imagine a CNC trying to hit position reading a geared clockface?

danlb
09-02-2014, 12:58 AM
As in vernier scale, As in the reader on any glass scale in any CNC.
Can you imagine a CNC trying to hit position reading a geared clockface?

Isn't that what a trav-a-dial does?

Dan

k2man
09-02-2014, 01:18 AM
Great info, thanks everyone. Really good info and insight here!


Sent from my iPad using Tapatalk

thaiguzzi
09-02-2014, 01:40 AM
If one's eyesight is still good, what's wrong with a good old vernier? Cheaper, robust and still accurate. As long as your eyesight is still good...

Old Hat
09-02-2014, 01:49 AM
If one's eyesight is still good, what's wrong with a good old vernier? Cheaper, robust and still accurate. As long as your eyesight is still good...

Nearly everyone is taught wrongly to read a vernier scale horizontally,
and if you have trouble close one eye.

A vernier scale is to be held vertically, with both eyes open.
It wouldn't matter if there were no depth to the surface of the fixed sale
or the reading scale, and to the etched lines, but there is depth
and even some difference in plain, made worse by lighting variations.

Reading vertically reduces and or elimiates these variables.
Also we use our vision poorly, fixating on targets by habit and inclination.

If you weld allot, you learn to let your eyes scan around, and build a far more
accurate composite image, like a DVD reader assembling the line of data
by working around scratches untill it has all the ducks in a row.

One cannot weld well by staring at your work.
You learn to quit staring at your machining and your instruments.
Vission can be excersised to assemble composite images at lightning speed.
And your eyes will not even become fatigued like when focussed and staring.

In thirty years of night driving, I've applyed this to blinding snowstorms and heavy fog.
By relaxing and wide rapid "lucid" scanning, I've avoided countless perills by seeing
them early as forming shapes instead of too late once you have a recognisable image.
==============
There's books and courses on this stuff.
Some have improved their eyes to the point of no longer needing glasses.
Stenopaic lenses train the eyes in this manner.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=10&cad=rja&uact=8&ved=0CFIQFjAJ&url=http%3A%2F%2Fmedical-dictionary.thefreedictionary.com%2Fstenopaic%2Bspe ctacles&ei=tl4FVJCDEMzNggSnkYK4Dw&usg=AFQjCNFf9lHERfOfSAss9V-tlFzhx0y72Q&sig2=3aKViz8boy4E4KITs8bt4Q&bvm=bv.74115972,d.aWw

darryl
09-02-2014, 02:26 AM
I like my dial caliper enough that I recently bought another one. The digitals stay in their boxes. Of course I use micrometers also- verniers.

Old Hat
09-02-2014, 02:40 AM
I like my dial caliper enough that I recently bought another one. The digitals stay in their boxes. Of course I use micrometers also- verniers.

Wow now there's a concept!
I gotta ponder that one for a while......

I just bought a set of metric impact sockets. There all on a plastic grid all sealed shut.
I'm gonna leave em that way to see if their usefullness is preserved somehow.

SGW
09-02-2014, 06:37 AM
As a side note, I find it rather interesting that something invented in 1647 (the vernier) is still being used for precision measurement over 350 years later.

vpt
09-02-2014, 09:06 AM
The deal with "not knowing" if a digi is at .00124 or at .000977 takes a "feel" to kind of know. While you don't get an actual reading I could always tell if the measurement was close to the next "roll over" number or not by simply rocking the caliper on a part a tiny bit and watching if the last digit changes right away with the rocking or if it takes quite a bit of movement before the digit changes.

But then again I don't make space shuttle parts either so working to the thou is good enough for everything I do.

Old Hat
09-02-2014, 10:57 AM
The deal with "not knowing" if a digi is at .00124 or at .000977 takes a "feel" to kind of know. While you don't get an actual reading I could always tell if the measurement was close to the next "roll over" number or not by simply rocking the caliper on a part a tiny bit and watching if the last digit changes right away with the rocking or if it takes quite a bit of movement before the digit changes.

But then again I don't make space shuttle parts either so working to the thou is good enough for everything I do.

It takes a "feel" to kind of know..... It's sad today that "feel" is outright discounted by many.
When carbide anvils first appeared on micrometers, many seasoned lathe-hands and cylindrical grinder guys
tryed them and found them unacceptable.

And I'm talking big work that ain't go'n back in the machine because a half thou was left on a turn.
Their complaint was that the jury's verdict came from the feel of passing the moving end of the mic
over the turn or grind. And the carbide had either a grip or a slip and nothing in between.

On a critical part a consences was taken of a few individuals "feel". Often the same few guys
who had a track record of hitting home-runs doing this.

A side note here . . . . a sort of rite-of-passage, was being asked to be part of one of these Jurys.
As I remember the first time I was invited, and who it was that stepped out for me.....
I'm welling up with tears. One of the highest points in my career.
Phil

gundog
09-02-2014, 11:17 AM
I own both and almost never pick up the mics I guess most of my work is not supper accurate. I machine a lot of plastic and due to thermal expansion keeping .010" is as good as it gets but the parts are not that critical for dimensional tolerance. I machine a fair amount of aluminum also and just use a mic and a part for test fitting. I know there are times when using a mic for accuracy is needed I guess I just don't make very many of those type parts.

Mike

Old Hat
09-02-2014, 11:33 AM
I own both and almost never pick up the mics I guess most of my work is not supper accurate. I machine a lot of plastic and due to thermal expansion keeping .010" is as good as it gets but the parts are not that critical for dimensional tolerance. I machine a fair amount of aluminum also and just use a mic and a part for test fitting. I know there are times when using a mic for accuracy is needed I guess I just don't make very many of those type parts.

Mike

I think you're not giving your style (you're approach) the credit it deserves.
You show that you have confidence in your consistancy. EXCELLANT ! That's the heart of the matter.
But by type "I guess I......." twice, it paints an unflattering portrait of you're abillities.

gundog
09-02-2014, 11:44 AM
I make stuff for money but I don't consider myself a true machinist as the only formal training I have was from high school in the 70's. I am self taught for the most part like many of the guys on here. I make make mistakes and learn from them. I don't have a job shop type business I make stuff for my business I can afford to make a few mistakes to develop a process to make the parts I sell and this works for me. I don't want to come off like a Pro Machinist because I am not or at least not the type guy who could walk right in a job shop and go to work making small tolerance parts. When I give my opinion it is with my limited experience. But I have made a lot of stuff over the years.

Mike

Old Hat
09-02-2014, 11:49 AM
So, maybe a Man might be found worthy, by looking more so at {what he can DO}.
And less so by what his official title is, No?;)

Toolguy
09-02-2014, 11:49 AM
Gundog -
I think you have a good attitude and are an asset to the Forums.:)

danlb
09-02-2014, 11:53 AM
As a side note, I find it rather interesting that something invented in 1647 (the vernier) is still being used for precision measurement over 350 years later.

As long as the basic rules of trigonometry remain the same, then the vernier will still work. Even without batteries! :)

Dan

A.K. Boomer
09-02-2014, 12:31 PM
they are amazing but you do need good eye's --- or at least a magnifier if you don't - and then you better be careful on your angle's

Old Hat
09-02-2014, 12:46 PM
Nah, it's Curves that ya have ta be carefull with.

Angles may challege you but Curves beckon.

gundog
09-02-2014, 11:18 PM
One thing that I will say about calipers is I have Ditched all the digital ones and only use the dial type. I have had too many failures with the digital ones cheap HF and a Mitutoyo I bought at a pawn shop they skip and fail the battery is dead Etc the dial type work each time I grab one.

Mike

Old Hat
09-03-2014, 02:57 AM
https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcTWUKm6oPnPykMVNXv0rc1vCNU5-q-J3laTZRVMVHtQF6pESHsx

The Dials 1 The Digitals 0
I gotta walk away from this one.

Tilaran
09-03-2014, 03:32 AM
I've got no time for dials, batteries , solar power and other such bovine excrement. Straight Vernier for this old man.I don't use calculators either. A pencil, soap stone, scratch awl.......Hell. I can even do multiples of 21 as long as I'm barefoot and my zipper is down.

Old Hat
09-03-2014, 03:39 AM
I share your sentament to a point!
I'd be OK if the world stayed with verniers.
How-Ever I'm no purist..........

A Bullard is in my top three for the funnest, and finest machine one could hope to use.
BUT
I'd think twice about that, if it were not equipt with a top tier DRO like say a Heidenhain.

vpt
09-03-2014, 09:02 AM
One thing that I will say about calipers is I have Ditched all the digital ones and only use the dial type. I have had too many failures with the digital ones cheap HF and a Mitutoyo I bought at a pawn shop they skip and fail the battery is dead Etc the dial type work each time I grab one.

Mike

Well now you know why the mitu was at the pawn shop. ;)

Old Hat
09-03-2014, 09:13 AM
My batterys last so long in my Mitutoyos I usually have no recollection of the last time I swapped them out.
I turn them off only at the end of the shift. And they all get heavy use.

Now if you dialiacs, are having that many issues with digitals, I have to question the integritty of the user and the ussage.
There are folks who can acheive failure as a default funtion. They don't even have to strain at it.

A.K. Boomer
09-03-2014, 11:05 AM
Dials are fine till they hit the floor - then their crap,,, I don't know how many times iv left my digies on the edge of an over crowed work bench and had them fall off. heck I think I even threw them against the wall one time because I was pissed, picked them back up and still good for + or - .0005" :p but you have to get the good quality chinese ones...

Willy
09-03-2014, 11:45 AM
There is definitely a place for both a good set of micrometers and calipers in the shop. I have both, although I must admit I use the calipers 97.5%(:)) of the time. Mostly because they cover a large range of measurement in one tool and subsequently are always on the bench. The fact that most of the work that I do does not require the accuracy level of my micrometers also plays a very big role in my choice.

Would I ever get rid of my micrometers? Not likely. Would I ever get rid of my calipers? Definitely not, I'd be lost without them!


The choice of digital, dial, and vernier is a personal one that comes down to a personal comfort level that one develops from using a tool. They each have drawbacks and advantages. Although I have 4 digital calipers my 6" Japanese Kanon vernier calipers are my favorite, they have been with me for about 40 years and are still as accurate as the day I got them. You will ALWAYS find them on my bench.
Being as near-sighted as Mr. Magoo helps in this respect as well. :p

Like I said, comfort level and confidence in a tool is important and this can take a little time to develop irregardless of what tool one is using, it does not matter if it is a mill or a micrometer.

oldtiffie
09-04-2014, 08:00 PM
I am posting this as a book mark (so it doesn't get lost) so that I can come back to it shortly.

I will tell how to use a digital caliper in conjunction with slip gauges (aka "Jo Blocks") to make the calipers "more accurate" and to simplify seeing directly "how much is left to be removed" and to simplify the maths for moving the machine dials - to potentially ease a common task and perhaps simplify things a bit to reduce a common error or two as well.

Later.

oldtiffie
09-05-2014, 04:08 AM
I have a couple of dial calipers - a digital and an older dial. As a kid, my dad had a couple of C shaped micrometers that I'd use some -don't know where these went to (brother probably gave away in a garage sale when he passed - like he did with my fiberglass canoe that my other brother, dad and I built.... grrrr... that's another story).

I'm buying my first lathe. Want a milling machine also, but may have to wait, but I do some machining with my drill press and xy table.

I'm building small parts - prototypes - usually less than 6" in any dimension.

My question is, do I need micrometers - or will dial calipers do the same job?

Provided that your work has a tolerance of +/- 0.001" or more your digital calipers will do the vast majoring of your work on diameters of about 3" or less and steps and depths from zero to 6".

Micrometers do meet a lot of needs but you will need at least 5 of them (0-1", 1-2", 2-3", 3-4", 4-5" as well as 5-6" to cater for jobs from zero to 6" on diameters and are reliable to/at 0.0001" (1 "tenth") as well for depths and steps.

A good Chinese 6" digital caliper as well as Chinese micrometres calibrated to 0.001" are usually very good quality and very cost-effective - so you can afford to buy new.

I have no reason to "rubbish" Starrett or Mitutoyo and similar which are excellent products but very expensive new.

I am very selective where I buy my Chinese "stuff" as I have only ever had one that I had to return for a new one and it was done without question right "there and then".

But others advice will vary and may well advise you otherwise as is their right.

My advice is no better than anyone else's - so get a lot of it from others too and make up your own mind.

Old Hat
09-05-2014, 04:22 AM
My advice is no better than anyone else's - so get a lot of it from others too and make up your own mind.

A rather odd statement there.
The only value any advice has, is it's better~ness,
Great advice is like Home Made Apple Dumplings, you go away pleased and saticefied.
You can fill a plate with factory made pie, and still wish you had some real desert to eat.

George Seal
09-05-2014, 05:19 AM
Tiff
Glad to see you back

J Tiers
09-05-2014, 08:35 AM
Gotta agree with the folks who suggest that calipers (I like the "always-work" dial type) are going to cover most of what is wanted.

Also, there are TWO KINDS of inch dial calipers ...... the kind that show 0.2" per revolution of the dial, and the kind that show 0.1" per rev. The 0.2" type are for general guesses......between all errors, including reading of the tiny scale, 0.005" or worse, is probably about their level of operation.

I have several 0.1" per rev dials, and, despite lots of opinions (including mine) about how calipers are good only to 5 thou, or maybe 2-3 thou (my opinion), the darn things repeat to a half thou when checked with mic standards or gage blocks. AND, you can actually SEE the dial without having to squint. One of the dials is chinese, and it does as well as the german-made Fowler, or the Kanon, Mitutoyo, etc.

A 6" dial caliper gets you into the world of precision measuring (no quibbling here, please) from 0 to 6" (0 to 150mm) in one step, and covers most of what you will probably need to do. As pointed out, you will need a whole fleet of mics to do the same thing.

When you need to add mics to the equipment, you will know it. And you will know why.

That said, you SHOULD own a 0-1" mic, it's just too handy for a lot of things you may need to do, and not overly expensive.

Now, if you use calipers, and want accuracy, you can't just close them with your thumb on that little wheel.

Squeeze them closed on the part with your fingers on the jaws, not with the wheel. Make sure the jaws are clean, and check zero before the measurement.

Don't force them, close them gently, so that the jaws are not tilted. The biggest problem with calipers is that the jaws can tilt, and put several thou error in the measurement. There are gobs, but they are generally spring-loaded, so you can fairly easily force them off-square.

JCHannum
09-05-2014, 09:05 AM
In the home shop where most work is one off, making part B to fit part A, which you made yesterday, calipers are fine as absolute accuracy is not that important. Usually a measurement is taken with the calipers and a part is made to that measurement with the same calipers. As long as the calipers are repeatable and the user has learned how to make repaetable measurements, all will be good.

I have and use almost exclusively a Mitutoyo 6" digital. I do have a 0-1" micrometer. I spent about ten years buying and selling precision tooling and have had calipers up to 12" or so at various times. I have kept none for my own use. For anything over 6", I have a Mitutoyo 0-12" dial caliper.

It always gives me a chuckle when someone states he has checked his tooling against gage blocks or standards and it is right on. It is human nature to fudge and there is nothing easier to fudge than the reading of a micrometer or caliper when the measurement is known as with a clearly marked gage block. The best way to learn to use a caliper or micrometer is to use a part of unknown size and practice until you are able to obtain a consistant measurement, regardless of what that measurement is. Caveats about heat and temperature variations and actual precision of the part pertain of course.

DS_park
09-05-2014, 09:21 AM
Great discussion here with lots of experienced input.

My vote is for one 0-1" micrometer and a 0-6" dial caliper.

I got by with the above for over 20 years with a made in Japan Peacock dial caliper (.001 marks on dial) and a Craftsman badged Starrett 0-1" micrometer (with vernier scale for .0001). The Peacock was fairly reasonable under a group purchase. The micrometer was a gift from my father.

Got to agree with the analog (dial / vernier) folks on this thread. The 0-6 dial caliper is pretty good to the .001" range and you can see slight under / over trends on either side of the .001 marks.

A.K. Boomer
09-05-2014, 09:46 AM
I would have to say JT hit on the single biggest error of calipers, any calipers, getting the jaws aligned properly.

if the part is light and small and fits in your hand its no problem - the caliper will self align the part and you can get a feel for it,

if the part is heavy or mounted to something solid then this effect can be huge, so much so that you can be reduced to + or - .005" or so if your not paying attention,

It takes a little while for me to get a fairly close measurement on something like an engine shaft or such using calipers, there's lots of "testing" and then drawing a conclusion and then it's just that, close - but not something you want to base a press-fit off of or anything like that,

on heavy or solid things the key is to let the calipers "float" as they will have to become the thing that gets self aligned with the jaws, kinda hard to do with something 6" or longer, so try to use with the most mass hanging lower and hold as close to center jaws without manipulating them,

on the flip side I used to make allot of key ways, hundreds at a time - delrin and they had to be + or - .0005" and my digi-cals are what I used to dial them in, then the final parts were verified with mics, light little parts that you can check quickly and use consistent uniform pressure from the same spot, and I do use the wheel --- get a feel for the wheel as it's mounted at the closest point to the guide rail and can be very consistent for tons of parts, it's subject to change from day to day with oils or such but you can adapt to that as long as your not changing things during, the wheels main drawback is it counts on friction for the pressure, so wipe your calipers down on the rail before use and take it from there, use them and compare with mics,

the wheel both creates and eliminates an error, it's frictional value may vary but it's pressure/angle contact with the main jaw is consistent - not so when using your thumb on the jaw itself as you have to push into it some and down too so you don't lose your grip, the angle of this is subject to change depending how your holding it,

there is no "right or wrong" here, both are good depending on how much attention your paying and which way you feel comfortable with, neither methods are by any means fool proof, for instance oil on the thumb-push can also make you have to put more of your pressure towards the rail so your thumb does not slip off, this can not only mess with your sense of feel, it can load the jaws different on the rail contacts, to each their own, im just saying I have achieved very consistent + or - .0005" with the wheel and I do consider that pretty good results for calipers:))

Toolguy
09-05-2014, 11:22 AM
When I want an accurate caliper measurement I pinch the jaws of the caliper on the part with thumb and index finger of the left hand while holding the caliper in the right hand. This gets the jaws aligned with the workpiece flat and parallel without putting any stress on the movable jaw which might make it either too loose (oversize reading) or too tight (spring the jaws out of parallel). To me this is the easiest way to get an accurate reading. On larger parts the caliper is light enough that it will self align to the part using this method.

danlb
09-05-2014, 12:16 PM
When I'm using a caliper during a roughing operation, I just what to know approximately how much is left to cut, so it's quick and simple and possibly sloppy.

When I'm getting close to needing a finishing cut, I usually measure it several times to be sure that I'm getting the same reading each time. If I get the same reading twice in a row I'm probably doing it right. This is, of course, for those operations where +-.001 is good enough. :)

Dan

loose nut
09-05-2014, 01:26 PM
When I want an accurate caliper measurement I pinch the jaws of the caliper on the part with thumb and index finger of the left hand while holding the caliper in the right hand. This gets the jaws aligned with the workpiece flat and parallel without putting any stress on the movable jaw which might make it either too loose (oversize reading) or too tight (spring the jaws out of parallel). To me this is the easiest way to get an accurate reading. On larger parts the caliper is light enough that it will self align to the part using this method.

+1 on that.

There is a video on Youtube that has a guy doing accuracy tests on digital calipers. Mitutoyo great, I-Gage good but all of the other Chinese ones failed badly. They may have good repeatability and linear accuracy but all of them (that he tested) failed in the parallelism of the jaws (tight at the tips but a couple of thou gap closer in or visa versa), alignment between the inside and outside jaws and some had gaps between the inside jaws when the outside jaws where closed. There were other faults too. You may get a good one but it is more then likely that something will be wrong with them. You buy cheap, you get cheap.

I used cheap calipers for years and finally broke down and bought a Mitutoyo Absolute digital. Using it for the first time was almost a religious experience, the sky opened up and light shown down on them, well florescent light anyway but the cheap ones even if OK just don't compare.

You can do good work on crappy machines with good measuring tools but its hard to get it right on good machines with crappy measuring equipment.

Old Hat
09-05-2014, 01:34 PM
+1 on that.

I used cheap calipers for years and finally broke down and bought a Mitutoyo Absolute digital.
Using it for the first time was almost a religious experience, the sky opened up and light shown down on them,
well florescent light anyway but the cheap ones even if OK just don't compare.

You can do good work on crappy machines with good measuring tools but its hard to get it right on good machines with crappy measuring equipment.

+1 squared.

J Tiers
09-05-2014, 08:44 PM
It always gives me a chuckle when someone states he has checked his tooling against gage blocks or standards and it is right on. It is human nature to fudge and there is nothing easier to fudge than the reading of a micrometer or caliper when the measurement is known as with a clearly marked gage block.

I know, we've all heard about inspectors "flinching" etc, etc. So it's ingrained to say... "that can't be trusted, you knew what it should be"... but I was more likely trying to see how much ERROR there was..... I wasn't expecting accuracy, so stopping at the spec point isn't likely..

besides, at some point you HAVE TO calibrate a tool, or measure a part. If you cling to the idea that NO measurement where the result is known can EVER be reliable, then there is a serious problem, and it might be advisable for you to take up knitting, or croquet, instead......

Just measure the same way all the time, and let it fall where it does..... Getting the "right" number does you no good if it won't fit with the other parts, no matter how much "wishing" you do..... "Wishing" doesn't do any good with real physical parts.

JCHannum
09-05-2014, 09:19 PM
I'm just saying, the best way to develop the touch needed for accurate repeat readings with a mic or caliper, is to practice with a piece with an unspecified dimension until a reasonable degree of repeatability is attained. At that point, the instrument can be zeroed with a jo-block or standard with some confidence the user will achieve accurate, repeatable measurements.

ahidley
09-05-2014, 10:41 PM
Toolguys way is how I do it also

A.K. Boomer
09-05-2014, 11:03 PM
+1 on that.

There is a video on Youtube that has a guy doing accuracy tests on digital calipers. Mitutoyo great, I-Gage good but all of the other Chinese ones failed badly. They may have good repeatability and linear accuracy but all of them (that he tested) failed in the parallelism of the jaws (tight at the tips but a couple of thou gap closer in or visa versa), alignment between the inside and outside jaws and some had gaps between the inside jaws when the outside jaws where closed. There were other faults too. You may get a good one but it is more then likely that something will be wrong with them. You buy cheap, you get cheap.

I used cheap calipers for years and finally broke down and bought a Mitutoyo Absolute digital. Using it for the first time was almost a religious experience, the sky opened up and light shown down on them, well florescent light anyway but the cheap ones even if OK just don't compare.

You can do good work on crappy machines with good measuring tools but its hard to get it right on good machines with crappy measuring equipment.


thanks for the heads up on the iGage, that's the one beef I have with most of my cheapies is the internal measuring being off... check out the u-tube test,
it actually just edges out the 120 dollar 4" mitutoyo and it's a 6" that I can buy for 22 bucks free ship...

http://www.youtube.com/watch?feature=player_embedded&v=1yqZx_FNbSs

I can see springing for the extra 4 bucks than what im used to if it will take care of that peskie internal measuring problemo that im always having to compensate for,
even if it's just going to get ran over in my garage or left under the hood of a car or worse yet pitched against the shop wall in a fit of rage... might be money well spent, or wasted - or whatever...

Edit; some of the testing quibbles are about useless to me but much of it is good,
the fact that the guys hand looks fresh from getting caught in some kind of machinery does not lend to his credibility well but for the most part I found it interesting and could be the answer to the OP's question of why not buy both if you buy right and still have quality and moneys left over...

burdickjp
09-05-2014, 11:38 PM
I use vernier calipers. They never need calibration, and it encourages me to grab my mics if I need more precision.

A.K. Boomer
09-06-2014, 12:20 AM
Incidentally, don't know if it's been mentioned, but calipers can measure inside diameters also - where as with mics your screwed unless you buy other equipment like telescoping gauges or the like,

so by far for a beginner who just is getting started and can only afford one and is not getting into extreme accuracy the calipers are very versatile - you don't need a whole set to go from 0 to 6" and they can do inside diameters where as mics can't...

even though I have a full set of mics and telescoping gauges I bet I only end up really needing/using them about 5% of the time...

thaiguzzi
09-06-2014, 12:37 AM
I use vernier calipers. They never need calibration, and it encourages me to grab my mics if I need more precision.

+1.

J Tiers
09-06-2014, 09:01 AM
Another issue with calipers is that they are intentionally designed to maximize errors.......:D

The first 10 or so mm out from the beam is cut away so that you cannot use it. There would be no problem if the cutaway was only 3mm, but it is traditionally a good deal more.

The whole issue of the jaws tilting would be largely removed for smaller parts if the jaws were made in such a way as to allow measurements closer to the beam.

As for the inside measurements, calipers WILL do that, of course. And do it well enough for many, even most purposes.

But that is a case where there really IS a built-in and totally unavoidable error.... The *inside* jaws have a small flat on them, and that flat will span a chord of the circle, reducing the measurement versus reality. The error is inconsequential for larger IDs, but at smaller sizes, it places a hard limit on the accuracy of the measurement.

Since not all calipers have the same size "flat" on them, the error can't be defined. I just checked two decent quality calipers, one German, one Japanese.... One of them has flats of about a half mm, the other has just under a 1mm flat, which clearly is going to be an issue for ID measurements.

Crazy mistyping corrected..... obviously "calipers" intended...

A.K. Boomer
09-06-2014, 09:45 AM
JT did you mean "calipers" in your first sentence?

I was trying to figure out what you were talking about in the second sentence about mics as it didn't fit but does for a caliper.

there is quite a cut away, I suspect there needs to be some for cleaning or you could never zero the things properly but 10 mil. is a little excessive, could be they wanted some space there for when your using it as a crescent wrench? would be the strongest place:p

Good observation about the ID flats, go too thin and they wear out quickly - go too thick and you can really change measurements for small ID's, really is one of those "is what it is" things and not much you can do about that, maybe slight convex to help keep the larger diameters true, and make them out of carbide...

Rosco-P
09-06-2014, 09:52 AM
If it hasn't been said already, you need and will use both. Calipers for quick and dirty measurment, Micrometers for accuacy. In the beginning a six caliper will do. Later you will want to add an 8" and a 12".

burdickjp
09-06-2014, 10:13 AM
I find it particularly difficult to get a repeatable measurement on many things using the inside jaws on a caliper, whereas I've had enough practice to be repeatable to +- 0.001mm with telescoping gages and mics.

A.K. Boomer
09-06-2014, 10:34 AM
If it hasn't been said already, you need and will use both. Calipers for quick and dirty measurment, Micrometers for accuacy. In the beginning a six caliper will do. Later you will want to add an 8" and a 12".

I would rather go the other way with them, at first glance I thought those little 4" Mitu's in the review looked a little funny but they make allot of sense - I rarely need the 6" part of my calipers and lets face it, when you get past 3" the jaws become useless for measuring the middle of longer round stock as they don't have the clearance.

on the rare occasion I do need to measure past 6" I just clamp whatever on my mills table and use my DRO and an edge finder, and with a repeat of 2/10ths on both sides it's a pretty good way to go and I can forgo the expense of having tools I rarely ever need just sitting in boxes 99.999999999999999999999999999999% of the time...

danlb
09-06-2014, 01:04 PM
The first 10 or so mm out from the beam is cut away so that you cannot use it. There would be no problem if the cutaway was only 3mm, but it is traditionally a good deal more.



I always thought that the small gap there was to let you measure the thickness of sheets or plate despite the edges being upset by the cutting process. It gets you beyond the burrs at the edge. It's similar to the small groove at the inside corner of a machinist square.

Dan

Rosco-P
09-06-2014, 01:21 PM
I would rather go the other way with them, at first glance I thought those little 4" Mitu's in the review looked a little funny but they make allot of sense - I rarely need the 6" part of my calipers and lets face it, when you get past 3" the jaws become useless for measuring the middle of longer round stock as they don't have the clearance.

on the rare occasion I do need to measure past 6" I just clamp whatever on my mills table and use my DRO and an edge finder, and with a repeat of 2/10ths on both sides it's a pretty good way to go and I can forgo the expense of having tools I rarely ever need just sitting in boxes 99.999999999999999999999999999999% of the time...

1) Not everything is the world is cylindrical.
2) Not everyone has a DRO on their mill, etc. to use as digital calipers.

Are you suggesting that the OP buy mics up to 6" as an initial purchase?

ahidley
09-06-2014, 01:42 PM
J tiers is correct about the flats affecting ID measurments

Danlb is correct about the clearance for the burrs.

I believe that they are just as accurate as mics. The problem of innacurracys from different people is what they are measuring. Example: measuring a 1.000 x 1.000 x 1.000 square cube. You put the jaws right across the center of the cube and you get 1.000 Now no two surfaces are perfectly parallel. Let's assume this is a milled cube. Now let's say it's out of square by .002 which is pretty good for the home shop mill. So one edge is 1.000 thick and the other is .998 thick . The calipers span the entire surface and take the biggest number, thus the caliper says 1.000 Now you put a Mic right in the center and get .999 and you say the calipers are off .001 But they are NOT

A.K. Boomer
09-06-2014, 02:18 PM
1) Not everything is the world is cylindrical.
2) Not everyone has a DRO on their mill, etc. to use as digital calipers.

Are you suggesting that the OP buy mics up to 6" as an initial purchase?


Not everyone, but k2man does, so if he wants he can totally skip your suggestions and save allot of money,

Im not suggesting anything with mics, just saying if he wants he can get by with calipers alone depending on what type of work he's doing - and even just 4" calipers if he wanted too esp. at first...

point being is the mill can measure the rest and any larger caliper is limited for certain things anyways so no huge advantage unless the parts immobile...

just sounds like he's trying to get by for now or he'd just buy both to begin with, and keep in mind it's just a suggestion yet one that has worked well in practice for me for several years now... :)

burdickjp
09-06-2014, 04:22 PM
I believe that they are just as accurate as mics.

Starrett's 799A-6/150 digital caliper claims an accuracy of 0.001" and resolution of 0.0005"
Starrett's 436 series of micrometers claim an accuracy of 0.000005" and have a resolution of 0.0001"

To be more fair, the calipers and mics that I personally use:
Starrett 125MEA-6/150 Vernier Caliper 0.02mm resolution, +/- 0.025mm per 300mm
Starrett V436.1MXRL outside mics have a 0.001mm resolution and +/- 0.002mm

So, yeah. Calipers very much are not as accurate as mics. There are ways to get even more ridiculous with measurements even with inexpensive mics, such as my Starretts, such as getting gage blocks for the nominal dimension you're measuring and calibrating on that before measuring. I've looked into this for the engines I build.


The problem of innacurracys from different people is what they are measuring. Example: measuring a 1.000 x 1.000 x 1.000 square cube. You put the jaws right across the center of the cube and you get 1.000 Now no two surfaces are perfectly parallel. Let's assume this is a milled cube. Now let's say it's out of square by .002 which is pretty good for the home shop mill. So one edge is 1.000 thick and the other is .998 thick . The calipers span the entire surface and take the biggest number, thus the caliper says 1.000 Now you put a Mic
right in the center and get .999 and you say the calipers are off .001 But they are NOT

I'm almost certain your example is what a surface plate and height gage are for, but am not positive.

Most importantly, what tool you use is as much dependent on the intention as the dimension. If the dimension isn't critical, then calipers are fine. If it is, but the allowable tolerance is within the precision of the calipers, then they could still be used.

Old Hat
09-06-2014, 04:36 PM
A Micrometer can be used accurately, or it can be substituted for a C-clamp.
A verier calipur uses the most inherenty accurate means of mechanical mearurment known to man. It's self.
Hence it can be used accuratly, or the right fool can find a way to miss-use it!

A dial calipur has several times the number of features prone to variance and or failure.
Hence a dial calipur can be used accurately, as long as it is kept in it's box 97% of the time.
And only used on Sundays, birthdays, and Holidays.

A digital calipur of quality, uses the most inherenty accurate means of mechanical mearurment known to man...
a verier scale. And a prUven technology the magnetic reader. It (a good one) is resistive to most
environmentally unfriendly conditions to a point.
Hence it is the first choice of fine tradesmen hobby-ists and mechanics WorldWide.

It's also the only measuring tool of the bunch with Balls, and a Sleak look to it!
The vernier has balls, but is as sleak as an abicuss.

hermetic
09-06-2014, 04:55 PM
I was brought up on imperial measurement, and later learned to use metric as well, I still use mainly imperial, as all my machines except my H mill are imperial. I have a couple of cheap electronic calipers 150mm/6" they are invaluable when dimensions are in metric, and provide an instant conversion from one to the other, I don't think I have a metric Micrometer, and have never needed one. sneak up on finished size with the caliper and then do the last few thou with a micrometer.

Rich Carlstedt
09-06-2014, 05:04 PM
I'm just saying, the best way to develop the touch needed for accurate repeat readings with a mic or caliper, is to practice with a piece with an unspecified dimension until a reasonable degree of repeatability is attained. At that point, the instrument can be zeroed with a jo-block or standard with some confidence the user will achieve accurate, repeatable measurements.

Default

Absolutely Jim !
I am repeating below, for the benefit of newbies, a post I made some years ago (11-6-2010) under the thread " Accuracy of digital verniers"



95% of the machinists I have worked with, and 100 % of the photos made by Dial/Digital Caliper manufacturers ARE DOING IT WRONG !
The holding of such an instrument by the beam and pushing the wheel yields errors...every time.
Stay off the wheel ! .......is the motto fellows
Yeah, I know it is fast, and if fast is what you want, then I guess it is OK, but it is a poor work habit
Do you put a mike on the part by only holding the thimble ?
Is it used like a "C" clamp ?
Of course not, and we were taught the correct way is to hold a mic by the frame , either with our small fingers or with your other hand.
The same applies to Calipers, the force of closing the jaws should ALWAYS be at the same point of measurement, and no hand wheel !
Use the hand wheel to open and close the instrument, and not for measurement!

I just went out into the shop and shot some photos, for Two reasons.
First to show the way to get good readings
Second to disspell the belief that calipers cannot read accurately..This is false assumption.
Now here is a Photo of a Caterpillar Wrist Pin.
I am measuring it with a Starrett 722 Digital Caliper
Note that the finger and thumb are at the same point as the desired measurement, on the anvils/jaws of the caliper, and the other hand supports the beam. No twisting or cocking forces and the head is free to slide for the accurate measurement

http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20tales/PB060083.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20tales/PB060083.jpg.html)
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20tales/PB060085.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20tales/PB060085.jpg.html)


Now lets talk about accuracy.
These are undoctored photos.
Note the reading above on the Starrett, about 2.4997
The 7 tenths are the 7 bars on the far right of the digits.
Not all digital Calipers have this, but this Starrett cost over $200 when I bought it, because of that accuracy.
I used it for years making dies, and it is a good tool . Like all measuring instruments, you should always measure twice, and use it with a mic or other tool if possible, when work becomes critical
Shown below is a Helios Micrometer, and note the reading on the same part.
It matches the Caliper.
Good techniques make good references and most important lead to more accurate measurement

http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20tales/PB060088.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20tales/PB060088.jpg.html)
Also note the mic is supported and fitted with one hand and the other just turns the thimble...again so no twist occurs

Once you start using the caliper this way, you will be pleasantly surprised by repeatable measurements
Now lets make chips !

Rich Carlstedt
Retired Manufacturing Engineer

ahidley
09-06-2014, 05:11 PM
Your points are correct. But this is a homeshopmachine bulletin board.

" Starrett's 799A-6/150 digital caliper claims an accuracy of 0.001" and resolution of 0.0005"
Starrett's 436 series of micrometers claim an accuracy of 0.000005" and have a resolution of 0.0001""

I'm not machining anything to .000005. Hell I cant even make a surface finish that smooth, but I don't need to either.

The person that started this thread is new and was asking what he really needed. My first post was to disagree with EVERY POST BEFORE MINE that said cailpers were only good for .005 accuracy. So if you want to bash me go ahead but if that's your choice please give the op a few grand so he can buy mics with EVERY.000005 accuracy that he'll never in his life use.

ahidley
09-06-2014, 05:18 PM
Sorry Rich the previous post was not directed ward's you. You were writing your post at the same time I was .

Old Hat
09-06-2014, 05:20 PM
Who are you mad at?
:)

ahidley
09-06-2014, 05:25 PM
Not Mr old hat either..

loose nut
09-06-2014, 05:34 PM
Just to add to the confusion, in the old, old, old days some machinists referred to mic's as "Micrometer Calipers" as opposed to "vernier calipers", which were the only kind available at the time. So you buy a mic and by definition have both.

JCHannum
09-06-2014, 06:41 PM
There is no confusion at all, micrometer caliper is the correct term. A caliper is a device for measuring between two points. The simplest calipers have no means of direct reading measurement and are used for transfer of dimensions or the dimension is read from a separate rule.

The vernier, dial and digital calipers under discussion here are properly called slide calipers to differentiate them from other types.

loose nut
09-06-2014, 06:52 PM
It might have confused people that didn't know that.

caveBob
09-06-2014, 06:57 PM
Default

Absolutely Jim !
I am repeating below, for the benefit of newbies, a post I made some years ago (11-6-2010) under the thread " Accuracy of digital verniers"



95% of the machinists I have worked with, and 100 % of the photos made by Dial/Digital Caliper manufacturers ARE DOING IT WRONG !
The holding of such an instrument by the beam and pushing the wheel yields errors...every time.
Stay off the wheel ! .......is the motto fellows
Yeah, I know it is fast, and if fast is what you want, then I guess it is OK, but it is a poor work habit
Do you put a mike on the part by only holding the thimble ?
Is it used like a "C" clamp ?
Of course not, and we were taught the correct way is to hold a mic by the frame , either with our small fingers or with your other hand.
The same applies to Calipers, the force of closing the jaws should ALWAYS be at the same point of measurement, and no hand wheel !
Use the hand wheel to open and close the instrument, and not for measurement!

I just went out into the shop and shot some photos, for Two reasons.
First to show the way to get good readings
Second to disspell the belief that calipers cannot read accurately..This is false assumption.
Now here is a Photo of a Caterpillar Wrist Pin.
I am measuring it with a Starrett 722 Digital Caliper
Note that the finger and thumb are at the same point as the desired measurement, on the anvils/jaws of the caliper, and the other hand supports the beam. No twisting or cocking forces and the head is free to slide for the accurate measurement

http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20tales/PB060083.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20tales/PB060083.jpg.html)
http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20tales/PB060085.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20tales/PB060085.jpg.html)


Now lets talk about accuracy.
These are undoctored photos.
Note the reading above on the Starrett, about 2.4997
The 7 tenths are the 7 bars on the far right of the digits.
Not all digital Calipers have this, but this Starrett cost over $200 when I bought it, because of that accuracy.
I used it for years making dies, and it is a good tool . Like all measuring instruments, you should always measure twice, and use it with a mic or other tool if possible, when work becomes critical
Shown below is a Helios Micrometer, and note the reading on the same part.
It matches the Caliper.
Good techniques make good references and most important lead to more accurate measurement

http://i273.photobucket.com/albums/jj220/StationarySteam/Shop%20tales/PB060088.jpg (http://s273.photobucket.com/user/StationarySteam/media/Shop%20tales/PB060088.jpg.html)
Also note the mic is supported and fitted with one hand and the other just turns the thimble...again so no twist occurs

Once you start using the caliper this way, you will be pleasantly surprised by repeatable measurements
Now lets make chips !

Rich Carlstedt
Retired Manufacturing Engineer

Thanks for posting this!

burdickjp
09-06-2014, 07:11 PM
I'm not machining anything to .000005. Hell I cant even make a surface finish that smooth, but I don't need to either.

The person that started this thread is new and was asking what he really needed. My first post was to disagree with EVERY POST BEFORE MINE that said cailpers were only good for .005 accuracy. So if you want to bash me go ahead but if that's your choice please give the op a few grand so he can buy mics with EVERY.000005 accuracy that he'll never in his life use.

I'm not trying to be an ass, just trying to support my claim with evidence.

I absolutely agree that calipers CAN be good below 0.005".

Someone earlier made a good point: if you're looking at maximum dimensions the caliper has the advantage of having a broader contact surface to measure off of.

Truthfully, we need more information to answer the OP's question. I work on a bunch of stuff under 6" as well, but a lot of it is spec'd to 0.001mm, so I need nice micrometers and a lot of warm up to get repeatable, whereas if I was doing the same exact thing on a different engine, for instance a small block instead of my litte 4 cylinders, I'd likely not need that.

oldtiffie
09-06-2014, 08:26 PM
0.001mm = 1mm/1000 = 1 micrometer (= 1um aka 1"micron") in metric terms and in inch terms is 0.03937/1000 = 0.00003937" which is near enough to 0.00004" or 0.4 of a "tenth".

https://www.google.com.au/?gws_rd=ssl#q=micrometre

http://en.wikipedia.org/wiki/Micrometre

And at level of accuracy and consistency the class of surface finish is?

https://www.google.com.au/?gws_rd=ssl#q=surface+finish

http://en.wikipedia.org/wiki/Surface_finish

https://www.google.com.au/search?q=surface+finish&biw=1920&bih=845&tbm=isch&tbo=u&source=univ&sa=X&ei=lKYLVIihMNPc8AWE0YLYBA&sqi=2&ved=0CDoQsAQ

Interesting.

burdickjp
09-06-2014, 09:19 PM
I can't find a currently available digital caliper from Starrett or Mitutoyo that offers smaller than 0.0005" resolution. I'm sure there's a reason for this.

I also can't find specs for the Starrett 722 to be able to comment on the above picture comparison between the calipers and micrometer. I'll just say I'm not convinced.

Rich Carlstedt
09-06-2014, 10:01 PM
The 722 was purchased in 1988 and was considered a super-precision Caliper as recognized by the price for it at that time.
I don't have a manual , left it years ago. It did not become a popular tool, because it ate batteries up. Even thought the screen goes dark the unit stays on and batteries last about 1-2 months. I solved that problem with a simple plastic insulating shim that is inserted into the battery pack in a second when not using the tool.

The point of my post was not to argue that a Caliper is as good/better than a mike, but to point out that improper handling methods pervade our trade and hobby. It does not do any good to argue specs, when use of the tool violates common sense or proper methods.

I cringe whenever I see the heavy handed use of ANY precision measuring tool.
Even cheaper tools respond more accurately when used properly.... and as Jim Hannum said ...practice consistency

J Tiers
09-06-2014, 11:42 PM
.
...........
The point of my post was not to argue that a Caliper is as good/better than a mike, but to point out that improper handling methods pervade our trade and hobby. It does not do any good to argue specs, when use of the tool violates common sense or proper methods...............


A very important point.

There is "potential" accuracy, and there is "as-used" accuracy.

The potential accuracy is determined by the mechanical setup of the device being used. The actual accuracy of graduations, rack and gear, or threads, etc relative to perfection.

The "in-use" accuracy is determined by the user. Even with an accurate mic, 10 good machinists will probably come up with 10 different measurements of the same item. They likely will not be grossly different, but they are unlikely to all be lock-step identical.

With a slide caliper, there are enough variables as-used that I would suppose the "spread" of measurements (sample range) would be larger than with micrometer calipers. Just that many more things to consider, and ways for the device to measure a different distance than the actual true part dimension.

Calipers do start out behind the 8 ball... Calipers have the measurement out at a distance from the "standard" (the calibrated scale). That adds problems and potential errors due to leverage, etc. (Abbe's rule, IIRC)

By contrast, the micrometer caliper has the measurement in-line with the 'standard" (ultimately, the spindle threads). This eliminates many issues otherwise present with contact type measurements.

oldtiffie
09-07-2014, 12:15 AM
Back to the Original Poster (PO) - ie the initial post:


I have a couple of dial calipers - a digital and an older dial. As a kid, my dad had a couple of C shaped micrometers that I'd use some -don't know where these went to (brother probably gave away in a garage sale when he passed - like he did with my fiberglass canoe that my other brother, dad and I built.... grrrr... that's another story).

I'm buying my first lathe. Want a milling machine also, but may have to wait, but I do some machining with my drill press and xy table.

I'm building small parts - prototypes - usually less than 6" in any dimension.

My question is, do I need micrometers - or will dial calipers do the same job?


My guess is that sooner or later you will need at least one micrometer - calibrated to 0.001" as it will work to 1 or 2 "tenths" if needs be - and they are cheaper than a "1 tenth" micrometer.

As for a caliper - I'd never go past a good quality digital caliper - Chinese (get good ones), USA (Starrett et al) or Japanese (Mitutoyo etc.) are all good.

And I really do prefer digital calipers (micrometers too) over "dial" or "vernier" calipers as I can "zero" a digital caliper (or micrometer) anywhere from the sliding jaw abutting the fixed jaw to any other point within the travel/scope/scale of the caliper/micrometer.

If I zero my digital caliper say at 1.000" either by positioning the sliding jaw either by using the scale or some part that I want to use as a "zero" or reference, the caliper will tell me how far I am from the required "zero" - which makes things easier on the mill or lathe as I can pick the number off directly instead of having to work it out as I would have to do with a non-digital caliper or micrometer.

So far the discussion seems fixed on outside diameters and straight edged/"flats" etc. and "holes" "bores" and "slots" are not addressed - but they need to be as they are more difficult than outside diameters and slots and flats..

But really, to get the best consistent results from the caliper or micrometer you really do need to practice and achieve the required "feel" or "touch" so the distances are correct and accurate and able to be consistently and accurately repeated under the same conditions at any time.

These are only how I use these tools in my shop and it is neither a suggestion nor a direction for anyone else to do the same - they can and should develop methods which suit them.

vpt
09-07-2014, 08:45 AM
I love the zeroing feature on digi calipers.

Slide out the digi to the projected size you want to turn the shaft in the lathe and zero the caliper. Then measure the material in the lathe and it will tell you exactly how much you have to take off every time you measure the material without having to do any math in your head. It will even tell you how much material to add back on after you turned to much.

I even use the zero at times where it is hard to reach and I can't see the screen and can't reach the lock. Just push zero button while taking the measurement, pull calipers out, slide shut, and there is your measurement.

A.K. Boomer
09-07-2014, 09:03 AM
If you can only afford one it's no contest, get the caliper, mics are severely limited and only do one thing good therefore you will actually turn out a better product with whatever your building using calipers --- Why? because you can measure more overall useful things.

outside diameters and a far wider range as it would take multiple mics to cover what one caliper can do,
inside diameters, mics alone ---------- nope, and again better buy a set of them after you buy your telescoping gauges.

like Tiffer just stated if you go digital all kinds of bonuses - for me it's the metric conversion at the touch of a button, mics? nope, or if they do don't think it would be in his price range if he's asking about what ones more important to buy in the first place.

Last but not least and I don't think mentioned yet, depth gauge, mics? NOPE, calipers YUP bottom line if you only have one mic most anything you build of any kind of detail will be a pile of crap - don't care if it's a mitu or starrett or whatever, caliper, not so, you can build entire complex things with just one tool,

so - if you can only afford one and that's what the OP is asking - by far a caliper "rules" no pun intended, it will be the best single purchase you can make as it will "teach" you how to build stuff with all the different things it can do,

where as one mic alone is about useless unless you plan on building little cubes the rest of your life, so - when only given ONE choice whats the better tool? absolutely no contest - get the calipers.

J Tiers
09-07-2014, 09:45 AM
Simplifying the problem to a very basic level.

If I had to have just ONE measuring tool for general purpose measuring of parts, that tool would be a dial/digital/vernier caliper. That will measure outside and inside dimensions to it's accuracy limit, and measures approximate hole dimensions

After that, the very next tool I would add is a 0-1" (or 0-25mm) micrometer, calibrated to 0.0001". It is strictly limited to outside dimensions, but will typically measure them to better accuracy than the caliper.

After those, the next would depend on what I was doing.

To step back for a moment, with ANY measuring task, you have TWO problems.

1) The basic problem of having a device which accurately and repeatably establishes any distance you want. Practical devices do this for some range, not "all possible" distances. Depending on the distance, and the required accuracy, that might be a tape measure, a machinists rule having an appropriate scale, a caliper, a micrometer, an indicator, a height gage, or, to jump to extremes, an interferometer. Each of these comes in various specialized types suited to different measurements.

2) The specific problem of getting the device to measure the part, or feature, in question. The desired measurement may be of a round hole, or an oblong hole, a length, a distance between the center lines of features, a slot which is down inside a bore, etc, etc. The measurement may be an "inside" measurement, or an "outside" measurement. The points to be measured may not even exist, such as the center lines of holes, where there is no material, the point is a theoretical or "imaginary" point that cannot be touched.

So, in some cases you can apply the caliper or micrometer directly to the part. You simply measure the distance between two surfaces. the part "senses" the surfaces, and gives the measurement at one time....

In other cases, the best tool for establishing the measurement, cannot be applied to the part. As an example, a micrometer cannot measure the ID of a bore. So now you have a problem.

This can be solved by a number of possible solutions. A direct reading bore gage, or some device that can be inserted into the bore, adjusted to touch it, and then removed and measured as an outside diameter.

Other problems, like slots, etc have other specialized solutions.

Here are a few specific tools

At top is a type of direct reading I.D. / bore gage. Not the best, but quite workable, although best when calibrated to the bore size you want to read. It will also do other inconvenient ID measurements.

Below that the t-shaped devices are also used for bore measurements. They are spring loaded, and lockable. They are allowed to (gently) touch the bore on a true diameter, then locked and removed, after which they are measured as an outside measurement with mic or calipers to get the ID.

The ball-shaped devices do the same, for smaller bores. They are also available in "half-ball" types, which will do shallow slot measurements. The screw at the end of the handle adjusts the diameter, so they are adjusted to just touch the bore, and then removed and measured as an OD to get the ID of the part.

The odd micrometer has larger discs on the spindle and anvil. With it, for instance, the width of a narrow ring inside a narrow slot, or the distance between two narrow slots, can be measured, since the discs will reach into the slot to touch the surfaces.
http://img.photobucket.com/albums/0803/jstanley/measuringtoolsIDandslot_zpsa1f4d7e5.jpg (http://smg.photobucket.com/user/jstanley/media/measuringtoolsIDandslot_zpsa1f4d7e5.jpg.html)
As you can see, there is virtually no end to the types of measuring task, and the specialized (and typically expensive) tools used to make the measurements.

IF you need any of the specialized things, you will know it, because you will discover that your existing tools will not measure what you need to measure. Then you get to decide if you have a one-time need, or if you are going to need to measure that a lot. For one-time need, a workaround may be best.

Up until you KNOW why you need more, your best bet is to have a dial/digital caliper, and probably a 0-1" mic (metric if you prefer) as the basic measuring tools.

RichR
09-07-2014, 12:36 PM
Last but not least and I don't think mentioned yet, depth gauge, mics? NOPE, calipers YUP ......

Prior to measuring depth with my digital calipers, I first measure the depth of a flat surface and zero it to remove the 2 or 3 thousands offset it has.

Old Hat
09-07-2014, 12:44 PM
Prior to measuring depth with my digital calipers, I first measure the depth of a flat surface and zero it to remove the 2 or 3 thousands offset it has.

A good point to make!
I try to keep enuff calipurs around as they age to afford the luxury of removing the tail-rod from one of each lenght.
This way I can measure in confined areas when needed.

A calipur with notable jaw wear becomes a scribe calipur, and the fixed jaw gets sharpened as needed.

vpt
09-07-2014, 06:45 PM
A calipur with notable jaw wear becomes a scribe calipur, and the fixed jaw gets sharpened as needed.

Thats good stuff and actually what I used my good caliper for many times. :O

Along those lines though what are some uses and ideas for old worn out/bad calipers?

Old Hat
09-07-2014, 08:42 PM
Along those lines though what are some uses and ideas for old worn out/bad calipers?

Stuff that comes in out of the field, tends to be nasty.
So my original Mitutoyo veriers from the lates 70's * * * are still in my arsenal.
I may need to have some Idea what I'm gett'n into, so why use my good weapons on this filth.
So off comes the tail-rods.

Also using CNC for one-ofs, is a little un-nerving, so scribe-lines take some of the suspence out or the adventure.
How accurate do scribe-lines need to be, so old calipurs become scribe-calipurs.

* * * My boss back then, required new hires to buy a name brand 6" and 12" vernier-calipur right off the bat.
His thinking was sound! Too stupid to learn to read a vernier? Gone by wednesday.
Can't spare the $$s from the pot, cars, and galls budget, gone by wednesday.

Avoids allota questions, No?

_Paul_
09-07-2014, 09:23 PM
A calipur with notable jaw wear becomes a scribe calipur, and the fixed jaw gets sharpened as needed.

I have a couple of calipers done similar to this:
http://i1177.photobucket.com/albums/x358/Donkey0atey/Modified_digital_caliper_zps862f6074.jpg

Paul

A.K. Boomer
09-07-2014, 09:30 PM
* * * My boss back then, required new hires to buy a name brand 6" and 12" vernier-calipur right off the bat.
His thinking was sound! Too stupid to learn to read a vernier? Gone by wednesday.
Can't spare the $$s from the pot, cars, and galls budget, gone by wednesday.



gone by Wednesday my arss, I never would have showed up on monday, fuque him... more important things to spend your money on then trying to please some prick...

PStechPaul
09-07-2014, 09:30 PM
This is a very appropriate thread for the class I am taking, which last Thursday recapped the obligatory safety stuff, and then got into hands-on identification of hand tools and measurement. We only got so far as a machinist scale, and having to read it in 1/32 and 1/64 graduations was a bit challenging. The metric scale was so much easier (as would be a scale graduated in tenths and 1/100ths of an inch). I have always thought (probably from my old mechanical drawing classes) to read a scale from the 1" mark and not from the end where zero "should" be. The wooden (and later plastic) architect's and engineer's triangular scales had zero marks about 1/4" in from their ends, so you could not use the end as a reference point.

I realize that machinist scales are precision ground so that you can rely on the edge being a true zero, and you need to use that when measuring to an edge, but I'd rather use an inner graduation for a reference point if measuring between two scribed lines. We will probably soon move on to the machinist square, with the usual angle, center, and protractor attachments, and then layout techniques with dye, scribers, prick punches, and center punches. There really are a lot of details involved in machining, even before you begin to remove metal (or add metal if welding).

Although much of this is review for me, I can understand why this preliminary material must be covered, especially for some who may have little or no experience. I am fortunate that my father was a machinist, and his father was a metal finisher, and my maternal grandfather was a boilermaker at Sparrows Point. As far back as I can remember, as a young child I was playing with pipe fittings, chunks of metal or wood, hand tools, electronic components, plus an old "Erector Set", and other things that nowadays would probably be considered "PG13" and too dangerous for a 6 year old to be handling as I did. I (and others of my generation) also had the benefit of being able take stuff apart and understand how they work and sometimes even put it back together successfully. Now most things have "no user serviceable parts inside" or are mostly electronic modules rather than discrete components. And we have become accustomed to a "throw-away and buy new" mentality.

Old Hat
09-07-2014, 09:37 PM
I have a couple of calipers done similar to this:
http://i1177.photobucket.com/albums/x358/Donkey0atey/Modified_digital_caliper_zps862f6074.jpg

Paul

Paul, I'm thinking I need to get on a boat and come be Your understudy for a time.
Why the he!! did I not think to trim the moving jaw?
Each time I trimmed the fixed jaw, :mad: not even one of each which might be defencable.:(

============
Oh OOh!
My world is crashing in on me now... think'n maybe I'm driving on the wrong side 'O the road as well.:eek:

Old Hat
09-07-2014, 09:41 PM
As far back as I can remember, as a young child I was playing with pipe fittings, chunks of metal or wood, hand tools, electronic components, plus an old "Erector Set", and other things that nowadays would probably be considered "PG13" and too dangerous for a 6 year old to be handling as I did. I (and others of my generation) also had the benefit of being able take stuff apart and understand how they work and sometimes even put it back together successfully. Now most things have "no user serviceable parts inside" or are mostly electronic modules rather than discrete components. And we have become accustomed to a "throw-away and buy new" mentality.

You like'n the class? I didn't read that closely I confess!

danlb
09-07-2014, 11:24 PM
Thanks to this thread, I placed an order for a .0001 micrometer online.

Then I thought about it and took a closer look at my mics. 5 out of 6 had verniers for .0001. I'd forgotten about that. I spot checked two of them and found they agreed with each other. I canceled the order.

Ironically, the 0-1" mic that is hanging from the peg above my bench for quick access is the one that has no vernier.

Dan

Old Hat
09-07-2014, 11:37 PM
I have "special" micromters.
No tenths verniers.

A 1/2" dowel O.D. = a skoash over .500 on the barrel.

A 8" X 8" core-block to go in an 8.0000 X 8.0000 pocket= just a shade under 7.999 on the barrel.

Do I owe the ISO guy a favor? Close my eyes and go by feel.