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form_change
06-22-2011, 05:15 PM
Every so often I see sets (typically incomplete) of gage blocks come up at auctions. I've always resisted buying any because I can't work out how I would use them. The most obvious use is for setting up a sine bar (but I don't have one). Checking/ calibrating measuring gear is another, although if I needed to do that I could probably more easily get that done with a temperature controlled calibrated set at work.
For those with a set what other things do you use them for? Are they one of those tools that with hindsight takes up shelf space and doesn't get used enough?

Michael

john11668
06-22-2011, 05:41 PM
Lots of imperial sets on the market here but most of us would need metric.
I dont think I could justify the prices being asked for metric for my home shop, although it would always be a nice thing to own.

Ridgerunner
06-22-2011, 06:15 PM
I sometimes use them to set up zero on a mill or lathe. Use a 1 inch block and when it just fits between an end mill and the work surface, you are at + 1 inch in Z. Same on the lathe for X and Z zero. Carbide cutters do scratch the block after time.

adatesman
06-22-2011, 06:29 PM
They're quite handy if you have a sine bar/plate or use a surface plate for inspection. Other thing that comes to mind is our QC manager would use them while calibrating micrometers to make sure they were not only adjusted properly, but also reading correctly at several points over their range.

Uncle O
06-22-2011, 06:36 PM
Check slot/key width. Set up sine bar.

Greg Q
06-22-2011, 06:45 PM
Just like the surface plate is the shop standard for "flat", so are gage blocks the last word in dimension. Like most guys here I buy a lot of measuring tools on ebay-my gage blocks allow quick calibration at a few random points in the range of the tool. There seems to be little point to owning micrometers unless you either send them out for calibration or do it yourself.

As others have mentioned, it is often handy to be able to build up some blocks to make an object of known exact dimension to work from. My mill for example has trays on each axis allowing gage block stacks to be built up. (I now have a DRO though-until then it was a great way to approach jig bore accuracy)

The other application that I use is with a comparator and a sensitive dial indicator. You wring a stack of blocks to equal the desired dimension, check it with the comparator, then compare that with the part you are inspecting. This gives a direct reading of deviation from the desired dimension.


Greg

JCHannum
06-22-2011, 07:12 PM
I have a set of gage blocks and find use for them from time to time in setting up, calibrating and occasional other uses. I don't have much invested in them and could do without them.

On the other hand I also have two sets of gage pins up to 1/2" and find them quite useful for measuring bores and indicating bores in on the lathe. I do not use my telescoping hole gages anymore for these smaller sized bores. These, I consider keepers.

tyrone shewlaces
06-22-2011, 07:26 PM
Good question that has a good answer (IMO) that is not addressed by tool manufacturers.

Gage blocks can be used for all sorts of things if a guy just had the accessory set. Here's a link to one on eBay:
Click here (http://cgi.ebay.com/BRAND-NEW-MITUTOYO-22-PCS-GAGE-BLOCK-ACCESSORY-SET-/170652705859)

A few shops I've worked in had these and we used them to set bore gages and the like. They are great for setting up comparative instruments like test indicators to measure a deviation from a target dimension, i.e. set the stack for your target dimension, then zero your gage on it so when measuring you can then get a quantitative measure of how far off of the target dimension your part is so you can adjust things to suit.

However, as you can see from the link above, the accessory sets typically are extremely pricey for a collection of a couple clamps and things that only need to be flat, in comparison to gage blocks which are flat as well as parallel and accurate in dimension. Seems like somebody would have come up with an inexpensive accessory set which could be used with anybody's gage blocks. Otherwise you're stuck with just a stack of blocks and limited utility.

Rectangular blocks are the most common, but the rectangular accessory sets are the most rare:rolleyes:

Square blocks (with the thru-hole) are less common and more pricey, but are a bit nicer to use and it makes it easy to stack up what you need very easily.

There are also round sets which can be had pretty cheap. They have a threaded thru-hole and are easy to set up. Typically I believe they aren't considered as high-precision as the high-grade rectangular and square blocks, but I have a set and use them from time to time. They are handy and you just need to know what accuracy you've got so you don't compound an error with a stack of several blocks. I've never seen an accessory set for those either but maybe they exist?

Anyways, here's the call to some tool company out there. Make a workable accessory set and sell it for a reasonable price. If they did this, they'd sell more gage block sets ! And we'd use them.

Mcgyver
06-22-2011, 08:43 PM
they do spend a lot of time in the drawer, but there's also lots of uses. In addition to the sine bar mention, you indicate a stack of them on the surface plate with a sensitive indicator then indicator the work - very accurate dimension measurement. The other day i used a version of that to measure the height of my lathe's cross feed screw axis relative to the dovetail horizontals - surface gauge on the way, indicator picking up the OD of the shaft, stack then put between way and indicator.

Later I used them to set the taper on the tapered gib. Long spindly piece in the vise with each end sticking out of the vise an inch or so and resting on a stack of blocks on the table. Two gauge block uses in a week :eek: - fast times at Mcgyver's shop!

low duty cycle, but close to indispensable the occasional time

gcude
06-22-2011, 08:44 PM
Starrett has useful information on the use of gage blocks with the accessory set.

http://starrett-webber.com/GB70.html

johnnyd
06-23-2011, 08:01 AM
Gary.....Thanx for the link. Nice info to have.

Much Grass :) (muchos gracias?)

John

Juergenwt
06-23-2011, 08:02 PM
Jo Blocks are for accuracy. Mostly used by tool and die makers in conjunction with a planer gage.Today the Cadillac gage has taken the place of Jo-Blocks, but Jo-Blocks are more versatile for instance when grinding slots. Cadillac gages are not cheap. Jo-Blocks are also used for setting Sheffield Gages to very close dim's for O.D. grinding. If you are a tool and die maker you know how a planer gage works. If not, it would take to some time to explain.
Using Jo-Blocks as a stop or for some other purpose not requiring accuracy from thousands to tens and millions of an inch or hundred's and micro in metric is like playing Mozart at a Rock concert.

tyrone shewlaces
06-23-2011, 11:43 PM
... is like playing Mozart at a Rock concert.

What... you mean like Eddie Van Halen? Steve Howe? Steve Via?

whitis
06-25-2011, 06:10 AM
While the accessorie sets are nice, you can basically do the same things you do with the accessory set without one. Instead of using the straight jaws, wring on a couple extra gage blocks and slide them part way off the edge. Or use your caliper jaws. Instead of the half round jaws, use a precision rod (such as a thread wire or pin gage or just a good piece of shafting which you can measure with the gage block set) or ball bearing. etc.

It is also possible to make some of your own accessories. In some cases you just need one good flat surface.

If you have imperial vs metric, use a calculator. You can get within 0.0001" or 0.00254mm.

You can use gage blocks as a height reference on a surface plate combined with a dial indicator or surface gage. If you don't have a height gage, you can use a magnetic base indicator holder (balance so it doesn't tip if using on granite). Make mics/calipers more accurate by using them as comparative instruments. Preset telescoping bore gages (use the extra block trick above). Check the travel on your mill table X/Y/Z axes. Check your skill with a micrometer or caliper. Sine bars, of course. Use them to calibrate your flatbed scanner (computer peripheral). Use them as reference objects when taking pictures. Set spring calipers. Offset a workpiece a known amount. Calibrate a microscope. Tiny parallels.
Make go/no go gages. Use instead of inside micrometers. Use with feeler gages to measure in places your other instruments won't fit. Setting buttons.
Checking your dial indicators for cosine error in a particular setup. Spacers for use with a square when measuring an object with protrusions.

Check your leadscrew pitch:
http://bbs.homeshopmachinist.net/showpost.php?p=510620&postcount=5
But insert another gage block in that setup. I.E. measure with 1 or 2 blocks not 0 or 1.

Checking calipers, mics: if the gage blocks, measuring instruments, and work are made out of the same material, than they will shrink/expand proportionally as long as they are at the same temperature. If they are different materials, calculate the error using coefficient of expansion, length, and temperature.

Bear in mind that you can often construct two or more stacks of the same height using a single gage block set, especially if you aren't setting to tenths.
This opens up some other uses.

Don't have a sine bar? Have a couple pieces of precision rod? Space them a known distance apart with gage blocks then use some more to set angle. Use some parallels. Be creative as to how to hold all this together.

You need to consider the errors of various setups, especially improvised ones. Include temperature error when dissimilar materials are involved.

If you have access to a good set at work, that is an advantage; you can check that any set you buy is good. You can use the gage blocks as a transfer standard to bring accuracy from work into your home shop.

The more things you have around, the more ways you can combine them.

Here are some pictures of gage blocks and other measuring instruments in use:
http://www.micro-machine-shop.com/mensuration_instruments.htm

You may not use them too often, in part to avoid wearing them out.

form_change
06-26-2011, 07:26 AM
for those of you that use your blocks for checking the calibration of your micrometers, do you adjust them or just note the deviation and take it into account when measuring?
I once learnt how to strip a micrometer and adjust it but I can't remember how it's done now...

Michael

John Stevenson
06-26-2011, 07:30 AM
I use them for making brush boxes for DC motors.

I stack the correct sizes together and put them in the vise and whack the brass sheet round them. This way I get perfect square corners and all to a uniform internal size to fit the brushes.

Mark McGrath
06-26-2011, 07:45 AM
I use them for making brush boxes for DC motors.

I stack the correct sizes together and put them in the vise and whack the brass sheet round them. This way I get perfect square corners and all to a uniform internal size to fit the brushes.

As good a use as any. :D

DATo
06-26-2011, 09:46 AM
I sometimes use them for making comparative measurements using an indicator and a height gage. For instance, if I have a part with a step on it I'd set the base of the part on the surface plate and take a direct reading over a combined stack of blocks for the exact measurement of the dimension I am seeking. I then slide the height gage over to the workpiece and run the indicator over the step and record the deviation between the indicator's reading over the blocks and my current reading over the step.

EDIT : With regard to your recent question: I adjust the precision tool to the block to make the instrument reading precise rather than allow for the discrepancy deviation when I use the instrument. I think most machinists would do it this way.

Jaakko Fagerlund
06-26-2011, 10:59 AM
for those of you that use your blocks for checking the calibration of your micrometers, do you adjust them or just note the deviation and take it into account when measuring?
I once learnt how to strip a micrometer and adjust it but I can't remember how it's done now...

Michael
The micrometer is adjusted if it indicates the wrong number (if the error is inconsistent over the travel, in to the trash it goes). Otherwise I'll forget what the proper offset was and in a hurry I can forget it all together that it shows the wrong number. Been there, done junk.

And in work the micrometers have to be adjusted as they are used by many others also. We have one good set of micrometers that is not used for work but kept as a standard and it is the set that we sent out for calibration and to get it certified. This way we can check the other mic's against the calibrated ones and be sure that the precision is still there without paying for every mic's calibration :) The calibration costs about the same as a good set of micrometers, around 600 EUR.

Tony Pratt
06-26-2011, 10:59 AM
I have always adjusted the tool to read zero as per the slip gauges[Jo blocks], I think this is the way to go and as I have 10 plus micrometers there is no way I could remember each seperate deviation. There should be a small side hole in the micrometer barrel which allows you to turn the barrel to re zero it with the small pin spanner supplied with every new micrometer.
Tony

DATo
06-26-2011, 11:11 AM
Here are some pictures of gage blocks and other measuring instruments in use:
http://www.micro-machine-shop.com/mensuration_instruments.htm

You may not use them too often, in part to avoid wearing them out.

In response to the link you posted I can only say .....
http://www.youtube.com/watch?v=QLu1SQlNnos

Mcgyver
06-26-2011, 11:55 AM
Here are some pictures of gage blocks and other measuring instruments in use:
http://www.micro-machine-shop.com/mensuration_instruments.htm
.

whitis, is that your site?

Jaakko Fagerlund
06-26-2011, 12:35 PM
Here are some pictures of gage blocks and other measuring instruments in use:
http://www.micro-machine-shop.com/mensuration_instruments.htm
Where does this 12 degrees come from?


For highest accuracy, the angle between the stylist & part surface should be as close to 12 as possible.

Horst
06-26-2011, 01:36 PM
I have a set of Mitutoyo Grade 2 that I purchased new. I didn't want used because these are "foundational" in that they are the most accurate things in my shop and as such cannot be checked for accuracy in house. I almost never use them. What I do use, for purposes already listed, are "Space Blocks". These are the round, screwed-together blocks mentioned. They run in the neighborhood of $30, so I needn't worry about handling them very carefully, and are accurate enough for the vast majority of what I do. If I need greater precision I will check a stack of Space Blocks using an indicator and height gauge on my surface plate. If I need better than that then out come the gauge blocks, but only for setting the Space Blocks. The gauge blocks do not leave the surface plate. I have several sets of Space Blocks but the nicest ones are from CDCO. They come in a nice wood case and screw together well. Hope this is helpfull.

Harvey Melvin Richards
06-26-2011, 04:12 PM
Where does this 12 degrees come from?

I believe that 12 degrees is specific to Interapid test indicators and would have come from the manufacture. Lots more info here: http://longislandindicator.com/p37.html

KEJR
06-26-2011, 07:35 PM
For certain measurements they are pretty useful. I was talking to a buddy the other day and he recomended that I make a height guage to find center of my lathe spindle (for setting cutting tools exactly on center). Now there are probably a half dozen ways of doing this, but if you have guage blocks you just turn a piece of scrap in your spindle and then measure to your lathe bed with the blocks, split the difference of your scrap piece diameter and you have pretty exact center. More accurate than cheap caliper type height guages and more versatile.

As others have mentioned, you can use them as a poor man's surface plate reference along with an indicator.

If you want to measure a milled or turned gap you can deburr the part and then use the guage blocks to get your measurement without removing your part in some cases.

You can use them as spacers when setting up work (just don't abuse them).

KEJR

form_change
06-27-2011, 04:54 PM
As I mentioned in the original post, most of the sets that come up second hand are missing a blocks - usually only a couple but sometimes quite a number. Typically they are not the blocks that are unlikely to be useful either. With only one or two missing you can mostly work around it, but one set I looked at had not only the 0.5 missing, but also the 0.1, 0.2, 0.3 and 0.4. Hmm.
Has anyone found a good source for replacement blocks? Option two is to buy a second incomplete set and make up one good set, but that seems an expensive way of getting a cheap set of blocks.

Michael

John Stevenson
06-27-2011, 05:06 PM
I wasn't being funny or clever when I said I bend brush boxes around mine.

Whilst clearing out a couple of local tool rooms i came across a large stack, imagine shoe box size, of loose slip gauges.

Now these must have been able to bought loose as there are loads of the same sizes in there, like twenty 1.250" I'm sure they never robbed twenty sets to get these?

They also have packing engraved on them with a vibro pen but they are slip gauges, some have Matrix on them which is a well known English brand.

I have managed to fill lost slots up in friends sets, sometimes, although there are many there are many duplicates. I also use them as packing.

I also found a set of carbide slips from the same place, complete set but to be honest I have never used them.

TGTool
06-27-2011, 05:27 PM
I believe that 12 degrees is specific to Interapid test indicators and would have come from the manufacture. Lots more info here: http://longislandindicator.com/p37.html

As the indicator point gets further from this angle, the cosine error means that each mark on the dial becomes increasingly inaccurate. So, an indicator might suggest moving .006, but the real distance might be .0062.

However, if it's only used a null device it wouldn't matter. That is, zero it on a part feature, then use your master height gauge to get zero again and read the feature height. It's the same position, cosine error or not.

DFMiller
06-28-2011, 01:30 AM
John,
You are such a practical guy. ;-)
I am glad to see you bash sheet metal to micron tolerances.
Dave

oldhat
04-25-2012, 11:31 AM
New to site reading older post.
Just a note when buying older gages block and pins in my research before buying my set.
I found out that it was not until the mid 70s forget the date 76? That the inch was set to 25.4MM before that the inch was not standard around world the USA, Japan, china, Russia, the inch was not the same.

Bill
:)

Forestgnome
04-25-2012, 12:50 PM
As others have mentioned, it is often handy to be able to build up some blocks to make an object of known exact dimension to work from. My mill for example has trays on each axis allowing gage block stacks to be built up. (I now have a DRO though-until then it was a great way to approach jig bore accuracy)

Greg

What kind of mill do you have? I've seen jig borers that have that type of setup, but use equipment-specific blocks. Would love to see a pic of your setup.

willmac
04-25-2012, 03:27 PM
I'm not sure what mill Greg Q has but see below for an example.

http://i122.photobucket.com/albums/o248/moorbrook1860/Thieltray.jpg

The circled part is an accurately ground plate with two stops on which you can stack up slip gauges. You put a dial gauge in the tee slot above and use it against the slip gauges. This allows you to make extremely precise moves in this axis. More importantly, since this mill has a rather limited Y travel, you can use a stack of slip gauges to extend the travel using the topmost slide which carries the vertical milling head. I have to say that I have only used it this way once, but it was a good way to do a specific job. The more traditional use for precise measurements in one axis is really not important any more given accurate DROs, which this mill has.

Mcgyver
04-25-2012, 03:37 PM
What kind of mill do you have? I've seen jig borers that have that type of setup, but use equipment-specific blocks. Would love to see a pic of your setup.


I've got the same for my XLO. The are not currently mounted but I have them - trays with indicators on each end for the x and y axis.

Speaking of gauge blocks, I used them on weekend setting up tool makers buttons - another infrequently used tool. They're just the thing when you need just the thing.

Clevelander
04-25-2012, 04:57 PM
would use his blocks to measure cuts to set his dial indicator to zero (that is to make up for insufficient travel on the indicator for a long cut that needed to be accurate beyond the level of what a graduated collar will provide.

Greg Q
04-25-2012, 07:02 PM
I have a Deckel mill, similar to the green Thiel (?) shown above. Friends with a Schaublin 13 and Perrin UF-1 have the same set-up, so that's four European toolmaker mills so equipped.

The Schaublin owner still uses this feature, along with retro sytled Mahr indicators. Looks cool, and provides all the precision a boy could want, especially since his mill has no DRO

Greg