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loply
01-13-2013, 05:44 AM
Hi folks,

I'm real good at measuring bores with my telescoping bore gauges, but, the smallest one in the set is really only good for holes bigger than 1/2".

I tried using the inside jaws on my vernier calipers but the results are not very repeatable.

What's the best way of measuring bores under 1/2"? I tried finding a smaller telescopic bore gauge but can't seem to find one.

I'm after an accuracy & repeatability of a thou or less if possible.

Cheers,
Rich

goodscrap
01-13-2013, 05:50 AM
Expanding ball type gauges I'd say, as an example see this page

http://www.arceurotrade.co.uk/Catalogue/Measurement/Inside-and-Outside-Gauges

Brian

SGW
01-13-2013, 06:56 AM
Second the ball gauges. FWIW they come in both full ball and half ball designs. I'm not sure of the relative merits of either. Maybe somebody else can elaborate. I've got a set of the half-ball type and like them.

Another way of measuring small holes is with a set of pin gauges.

Note that the surface finish on the hole has a big influence on the reading you get.

willmac
01-13-2013, 07:23 AM
There are different types of ball gauges. Some of them expand two halves to contact the bore. I think the Starrett gauges are like this. Others have actual ball bearings that are pushed out through holes by a conical plug. My Moore and Wright gauges are like this. I wouldn't claim either type is better than the other, but you do need to get used to using them, particularly the required feel to get really accurate results, just like any other tool of this type. Since you already use telescopic gauges you will understand what this means.

Pin gauges are very useful, but you need a lot of them to be generally useful and that can be expensive.

Whatever you do, don't rely on vernier calipers for accurate small hole measurement (or even bigger bores for that matter). As you have found, they are neither repeatable or accurate to the level required for typical boring tolerances.

bob308
01-13-2013, 08:05 AM
the half ball are used to measure the bottom of slots and blind holes.

gwilson
01-13-2013, 08:27 AM
I use ball gauges,too. But,I found a pair of very unusual mikes. They look like retractable ice picks. Their blades are precision tapered. You stick them into a hole,with the body of the mike right up against the hole. A scale read through a window on each mike tells the diameter of the hole,based on how far the tapered blade went into the hole. It goes down to .020" holes. The other mike does a larger range,but both are for fairly small holes. I have no idea where to get them. You might could make some. These mikes are not good for holes of limited depth,though. Only through holes.

loply
01-13-2013, 08:46 AM
Thanks folks, I've ordered some ball gauges and will see how I get on. Never seen them before.

It did occur to me to make a tapered plug, measure it and mark the width at various points, but I knew there'd be an easier solution!

zimma
01-13-2013, 09:07 AM
I found a pair of very unusual mikes. They look like retractable ice picks. Their blades are precision tapered. You stick them into a hole,with the body of the mike right up against the hole. A scale read through a window on each mike tells the diameter of the hole,based on how far the tapered blade went into the hole. It goes down to .020" holes. The other mike does a larger range,but both are for fairly small holes. I have no idea where to get them. You might could make some. These mikes are not good for holes of limited depth,though. Only through holes.

Here is a couple of photos of my set of measuring gauges as you describe

There are 8 in the set

1. 0.25mm - 1.00mm x 0.025mm
2. 0.75mm - 2.00mm x 0.025mm
3. 2.00mm - 3.25mm x 0.025mm
4. 3.25mm - 4.50mm x 0.025mm
5. 4.50mm - 6.50mm x 0.025mm
6. 6.50mm - 8.50mm x 0.025mm
7. 8.50mm - 10.50mm x 0.025mm
8. 10.50mm - 12.50mm x 0.025mm

http://farm9.staticflickr.com/8211/8376762346_3ccb4660de_k.jpg
http://farm9.staticflickr.com/8374/8375687295_db63d2cce0_k.jpg

Regards

Graham

polepenhollow
01-13-2013, 09:11 AM
For smaller dia holes you can use a gage pin, or 2 gage pins added together to determine a bore dia, or a dowel pin and a gage pin, or a bearing ball with a gage pin, added together.

Stepside
01-13-2013, 09:17 AM
Starrett makes a set of taper gauges #269A and #269B. #269A is for .100 to .500 in .001 and #269 B is .500 to 1.000 in .001

For what I am doing ithey work well. I also have the ball gauges and the T-gauges. With all of the different style it is a "feel" technique. Also burrs and rough surfaces affect the outcome. If I am not sure I will use two of the types to see if they agree.

The beauty of the tapers is they are direct reading, no micrometer is involved and it is "one handed". The down side is it only measures the diameter or width at the part surface. The ball and snap gauges can measure a distance down the bore or slot. They are more "feel" sensitve and require 2 hands to set and 2 hands to measure.

Boot
01-13-2013, 09:33 AM
I just like to add my $.02. Shop I retired from used dial bore gages for small bores and also checking internal o-ring grooves. These were set up by using gage blocks in a special holder and were very accurate. Boot

KiddZimaHater
01-13-2013, 11:36 AM
http://ts4.mm.bing.net/th?id=H.5024794722173231&pid=15.1

firbikrhd1
01-13-2013, 12:03 PM
the half ball are used to measure the bottom of slots and blind holes.

Is there any reason that the half ball types can't be sued to measure a bore as well as a slot or blind hole? I would think they are capable of everything a ball type is capable of but my intuition may be flawed.

lakeside53
01-13-2013, 12:09 PM
I use pin guages a lot, then snap guages for sub-thou (if they fit) when I'm in the ball park. Over the years I've acquired complete sets of quality pins (mainly from machine shop auctions) from 0.008 to 0.750 in 1 thou steps.

But take great care. Hot work and cold close-fitting pins are not a good combination... Once I has to use vice grips (ARGGHHH) and in another - machined off my precious work to get the pin out.

No matter what technique you use, measurement of all bores is very dependent on surface finish.

bob308
01-13-2013, 01:10 PM
no you could use the half ball for holes. but you run the risk of getting a false reading if you are not dead squire in the hole.

JCHannum
01-13-2013, 01:34 PM
Not yet mentioned for hole measurement is the Brown & Sharpe Parallel Taper Gauges. These measure holes from 1/4" to 1". They are no longer manufactured, but appear on eBay occasionally, usually mis-identified, and usually go for a low price. They were furnished as a set in a fitted box and work much like adjustable parallels. If you run across a set, get it, they are well worth having as they measure hole size directly and are quite accurate;

http://i320.photobucket.com/albums/nn351/jchannum/P1060505.jpg

The only problem with these is common to the other tapered gauge devices, which is they can only be used in through holes or bores that are deep enough to accomodate the unused portion of the taper.

Bob Fisher
01-13-2013, 05:04 PM
I have two sets of pin Gage's up to .5 in. I find them the easiest and most accurate method. Bob.

TGTool
01-13-2013, 08:41 PM
I have a set of the Moore and Wright gages and they're a very nice build with little polished balls that are spread by a tapered pin. The smallest goes down to .110 dia. and the largest to 1/2". The problem is that they don't get used much because I've never developed enough confidence in the feel. It's not because I don't think I have a good feel on tools but because these are so different. I compare them to telescoping gages and they just aren't.

I was taught by the lead man and jig grinder operator to use telescoping gages by snugging them up not too tightly, then dragging them through the bore just ONCE. Pay attention to the feel of that drag through the bore, then wave them through the anvils of the mic as you slowly adjust it and find exactly that same feel. There's your measurement. I know some scoff at accurate measurements with telescoping gages but I will tell you that we consistently measured to plus or minus a couple tenths with some experience. The application was grinding rings for shrink fit carbide inserts so errors would come to light - either the inserts would fall out or the rings would split.

With the M&W small hole gages unfortunately it's been hard for me to find that same sense. The balls are smooth and polished and it's been difficult for me at least to find the equivalent feel to that of telescoping gages. God knows I've tried. Just to calibrate my fingers for an unknown hole task I'll take a reamed hole, check it with pin gages so I know I'm within .001 and can estimate around that by how tight a fit that is. Then I'll get out the ball gages and I'm all over the map. It's just awfully hard to get exactly that first contact without additional pressure and then to replicate it with the mic. YMMV

Don Young
01-13-2013, 09:11 PM
The split ball gages can be pretty accurate if they are of good quality and you practice a bit with them. Some of the cheap ones do not have a nice smooth adjustment and that makes them hard to use.

darryl
01-13-2013, 10:45 PM
Seems to me that the taper gauges are prone to error if there's any bell-mouthing.

I like the idea of the split ball gauge. You could probably make your own- might be good if you have only a few sizes of small hole that you commonly do. The measuring tip doesn't have to be a ball- it can be a split ufo shape, which might be useful to gauge depth of grooves. For that you would definitely need to use a graduated taper pin, which you would return to position after removing the tool to be measured by the mike.

robosilo
01-13-2013, 11:04 PM
split ball gauges are nice but if you can afford it, go with pins. Pins make it easier to check if there is a taper and you don't have to worry about applying to much or too little pressure to get an accurate reading. But that's my opinion. Some people are perfectly comfortable with split balls and telescoping gauges but i've i prefer a more direct method of measurement. A 0-.500 is often more than enough since you can put 2 pins together to measure holes larger than .5 (.999 in theory). Just make sure you take into account the fact that many pin sets are + or - the size they list.

Dr Stan
01-13-2013, 11:34 PM
Typically I also use ball type small hole gages, but learned to use inside calipers AKA Yankee calipers in Machinery Repairman School. Here's a link to an example: http://www.travers.com/product.asp?eaprodid=63345-57-065-370&r=s&n=||UserSearch%3Dinside+calipers||UserSearch1%3Dbl ock+id+63345+and+class+level3+id+29821

oldtiffie
01-14-2013, 01:49 AM
Any help?

http://www.machineryhouse.com.au/Q1595

Black_Moons
01-14-2013, 03:30 AM
If you have an important job, making your own tapered plug can be worth the time!

Consider multiple tapers, an initial steep taper to let you know when your sneaking up on the size, then a long taper thats only say 0.001" per inch up to the final size you need.

Mcgyver
01-14-2013, 07:41 AM
Some interesting tools in this thread


I have a set of the Moore and Wright gages and they're a very nice build with little polished balls that are spread by a tapered pin. The smallest goes down to .110 dia. and the largest to 1/2".

I've a set, goes down to .0625. Other than pins, nothing else I have goes that small. I get your point on the feel; small hole gauges present a larger radius surface on the gauge to the worksurface than the M&W ones, maybe thats it. As to the sensitivity, I agree sub thou is not too difficult with some practice and care. It's interest to note how what you thought was a decent finish feels like canyons and mountain ranges as you're setting the ball or telescoping gauges - this suggests they pick up very small differences quite well.

I set telescoping gauge by slight tightening at an angle then straighten and draw through the bore and out. Their clamping action is enough to keep them in place against a mic's pressure, but is not so rigid that this action won't push in the arms in to measure the bore. Small hole gauges without the off kilter part; just movement and very carefully opening them up until i feel the walls. To measure I slowly close up the mic while sweeping the gauge between the anvils and do so a few times to make sure I've got a consistent answer. imo you can't just measure across either small hole or telescoping gauges as they're no way to be certain you're across the widest part....sweeping addresses that.

Are they calling them ball gauges now? I've always called the small hole gauges, what it says on the Starrett and Mitutoyo packages. Mitutoyo have a slight advantage in that the balls are cut off (hurts typing that) so they can get closer to the bottom of a blind hole. I also have a bunch of small size bore gauges and pin gauges but 99% of the time the small holes gauges do the trick

JCHannum
01-14-2013, 08:04 AM
Starrett has the whole ball and half ball, they also have long and short handle variations. All have their uses. I have never seen the M&W gages in person, but from the photos I was able to turn up, they appear to be somewhat cumbersome to use. Jan might find the Starrett or Mitutoyo gages more user friendly.

I have accumulated almost all of the above mentioned gages, including the B&S parallel gages. For under 1/2", I almost exclusively use the pin gages, just the opposite of McGyver. You pays your money and you takes your choices I guess. If I did not have the pin gages, I would have no problems with using the Starrett small hole gages.

oldtiffie
01-15-2013, 05:00 PM
I decided to give pin gauges a miss because of expense and that they are in 0.001" or similar "steps" whicjh means that given the accuracy (very high) accuracy of the pins means that if the hole is just under the pin size it can be "grabbed" and smaller than the hole it becomes a case of "feel" to get those "tenths" of hole size.

Further, hole taper can be a problem as a single pin will not tell you where it is (front or back) or what the taper is. If the taper gets larger as the hole gets deeper you cannot measure it with a pin and if the taper gets smaller as it gets deeper it is all too easy to "jamb" the taper in the hole and in worst cases very hard to get the pin out.

http://www.google.com.au/search?q=pin+gauge&hl=en&tbo=u&rlz=1W1IRFC_enAU360&tbm=isch&source=univ&sa=X&ei=Us71ULDtE4rVkQXl-oHQAQ&sqi=2&ved=0CDwQsAQ&biw=1920&bih=818

http://www.google.com.au/#hl=en&sugexp=les%3B&gs_rn=1&gs_ri=hp&cp=7&gs_id=s&xhr=t&q=pin+gauge&es_nrs=true&pf=p&tbo=d&rlz=1W1IRFC_enAU360&sclient=psy-ab&oq=pin+gau&gs_l=&pbx=1&fp=1&biw=1920&bih=818&bav=on.2,or.r_gc.r_pw.r_qf.&cad=b

See http://www.cdcotools.com/ and search for items 34501 to 34515 - but they are expensive.

lbhsbz
01-15-2013, 05:51 PM
I have a mitutoyo dial bore gauge that goes from about .25 to .60" with 0.0001" resolution. For stuff smaller than that, I generally use wire gauge drills as gauge pins. I'll also make my own gauge pins on occasion, then verify the dimension with an OD mic.

oldtiffie
01-15-2013, 07:35 PM
I get by very well mostly with the small ball and telescopic bore gauges.

http://i200.photobucket.com/albums/aa294/oldtiffie/measuring/idmeasdevice1.jpg

"Feel" and "setting" as well as "reading" (on a micrometer) are all-important manual skills that have to be worked at to master them and to keep them current.

For larger holes I use the old-fashioned "spring" or "friction" calipers.

"Feel" and "setting" as well as "reading" (on a micrometer) are all-important manual skills that have to be worked at to master them and to keep them current.

I can quite easily keep to 0.01mm (0.0004") relatively easily although I have a few "practice runs" if I've been out of practice for a while (better safe then sorry).

I have several other bigger/longer bore gauges as well for larger holes but they don't often get used as I use "expending ball, or "telescopic" bore gauges in preference to them.

loose nut
01-16-2013, 06:39 PM
Pin gauges by Starret or other brand names should be considered accurate but how about the cheaper ones from CDCO, Little Machine Shop, Enco etc. How accurate will they be?

oldtiffie
01-16-2013, 06:49 PM
Pin gauges by Starret or other brand names should be considered accurate but how about the cheaper ones from CDCO, Little Machine Shop, Enco etc. How accurate will they be?

As previously:

See http://www.cdcotools.com/ and search for items 34501 to 34515 - but they are expensive.

Limits are +0/-0.0002"

oldtiffie
01-16-2013, 08:22 PM
split ball gauges are nice but if you can afford it, go with pins. Pins make it easier to check if there is a taper and you don't have to worry about applying to much or too little pressure to get an accurate reading. But that's my opinion. Some people are perfectly comfortable with split balls and telescoping gauges but i've i prefer a more direct method of measurement. A 0-.500 is often more than enough since you can put 2 pins together to measure holes larger than .5 (.999 in theory). Just make sure you take into account the fact that many pin sets are + or - the size they list.

Its best done with 3 pins - just a neat fit in the hole - a bit of math/trig - and no micrometer - and there you go.

All three pins should be no more that 0.003" between highest and lowest if pins are in 0.001" steps ie required size +/- 0.001"

http://i200.photobucket.com/albums/aa294/oldtiffie/Sketches/Proof-3rollersandbore1.jpg

kwoodhands
01-17-2013, 10:30 AM
You can buy plug gauges or make a few of your own. If you only need a few of a certain size,turn it on your lathe. Example, .250 one end.251 the other end. Check out Grizzlies catalog for "Steel Plug Gauges". In the 2011 catalog it is on pg 672.
mike

Rosco-P
01-17-2013, 10:51 AM
Pin gauges by Starret or other brand names should be considered accurate but how about the cheaper ones from CDCO, Little Machine Shop, Enco etc. How accurate will they be?

Really depends on the accuracy of the measurement that you seek. I think that they would be more reliable than ball or half-ball hole gages that require some degree of "feel". I'd shy away from the cheapest sets, but a set up to .250 inch, costing around $75 should be reliable. Measure a few of the pins with mic. and see what you get. Bargains on name brand gage sets (Meyer, etc.) can often be found on Fleabay or at local machine shop auctions.

loose nut
01-17-2013, 06:45 PM
As previously:

See http://www.cdcotools.com/ and search for items 34501 to 34515 - but they are expensive.

Limits are +0/-0.0002"

I know what it says Tiffie but can we believe it. Chinese test reports are questionable at best.

oldtiffie
01-17-2013, 06:56 PM
I've bought a few items from CDCO over time and its all been a good products - and postage here to Australia is expensive - and a "return" is even more so.

If I needed a pin set - based on my experience so far and having seen no adverse reports - I'd buy it from CDCO.

If you buy a set and go through them and measure them and if any are faulty I'd be confident that CDCO would replace them.

tdmidget
01-18-2013, 12:08 AM
http://ts4.mm.bing.net/th?id=H.5024794722173231&pid=15.1

No such thing:
http://ecatalog.starrett.com/#

Couldn't you people trouble yourselves to look at such items as the Starrett catalog so that you might know what you are talking about?
Small hole gages are NOT ball gages
telescoping gages are not "snap" gages

Machtool
01-18-2013, 12:40 AM
Small hole gages are NOT ball gages
You best get right on to Starrett about that. Page 300 of the catalog you just listed.

Starrett's own description.

These full ball gages are used for general work

Direct link here to Starrett's own site.

http://www.starrett.com/metrology/product-detail/Precision-Measuring-Tools/Precision-Hand-Tools/Hole-Gages/Small-Hole-Gages/S829EZ

Machtool
01-19-2013, 05:39 AM
Bump.

Just wondering how Captain Nasty got on with informing Starrett of them refering to their #829 gages as "Full ball gages".

Jaakko Fagerlund
01-19-2013, 08:16 AM
About measuring bores with a caliper: Yes, it can be done accurately, you just need to take a micrometer reading over the jaws once you get the thing locked in the bore and removed. Doing this every week on bores ranging from 15 to 200 mm and hasn't failed except for user error (jaws wobbling in the bore). Accuracy? Down to the 0.01 mm, verified with 'real' bore gauges.

And before someone jumps into say that the jaws are not contacting from the middle point: Draw a picture and think about it a minute or two.

Mcgyver
01-19-2013, 10:37 AM
And before someone jumps into say that the jaws are not contacting from the middle point: Draw a picture and think about it a minute or two.

so you are mic'ing across the corners of the caliper points? its using it sort of as a makeshift hole gauge then, your'e not using the caliper to measure just as a way to convert ID to an outside measurement. I can see how it could work, but don't think it would have the same sensitiviy or accuracy as small hole gauges as the ergonomics of the small hole gauges would be better at carefully picking up the ID.

Jaakko Fagerlund
01-19-2013, 02:34 PM
so you are mic'ing across the corners of the caliper points? its using it sort of as a makeshift hole gauge then, your'e not using the caliper to measure just as a way to convert ID to an outside measurement. I can see how it could work, but don't think it would have the same sensitiviy or accuracy as small hole gauges as the ergonomics of the small hole gauges would be better at carefully picking up the ID.
Yeah, and it is actually quite sensitive measurement, easily reproducible to the 0.01mm. Just requires calipers with a locking screw and some bit of learning to reposition it in the hole so it is tight before final locking.

For very small bores it is more difficult to use, as the jaws don't enter the hole that much.

Mikey
01-19-2013, 05:10 PM
Accurately measuring small bores can be a pain when the work is in the chuck. I've used pin gages, inside micrometers, an Alina bore gage, and small hole/ball gages and find that the small hole gages are not only easy to use, they can be very, very accurate.

I have both the full ball and half-ball Starrett gages and both read the same in a bore. The half-ball is useful in shallow bores that won't fit the full ball; otherwise, there appears to be little difference in their capabilities.

The problem for me was knowing if the reading I got was really accurate. I have read the "feel" thing many times but my feel might be different from someone elses feel, and neither may be realistically accurate. I have since found that technique is much more reliable than feel, at least in my case. In order to be confident in my technique I resorted to a known standard - a ring gage (a master ring calibrated in tenths). This allowed me to learn how to set my gage consistently and then learn how to measure the ball or telescoping gage in the micrometer. Knowing what the reading should be, it was a simple matter of learning how to reproduce the ring gage dimension accurately. A micrometer stand is an invaluable third hand in this process. I now use the ring gage to tune up my technique when I haven't bored for awhile and I'm confident in my readings.

With that said, unless I need to bore a hole to tenths I simply use the inside micrometers. They are accurate in the thousandths and are very fast to use on a chucked work piece. The ring gages will tell you how to use these, too.

Hope that helps.

Mikey

tdmidget
01-19-2013, 11:23 PM
Bump.

Just wondering how Captain Nasty got on with informing Starrett of them refering to their #829 gages as "Full ball gages".

They didn't. They referred to them as "small hole gages" and "full ball" is one style of them.

"Ball gages" are made by others.
http://www.precisionballs.com/all_ball_gages.php

RussZHC
01-20-2013, 12:13 AM
Mikey: good point and suggested solution. I struggle with mics too, wondering if the same amount of pressure has been used or, more, is that "slip" the same as the last in terms of effort (if that makes any sense) And WELCOME.

tdmidget: thanks for the link, always learn something here, the "Balwand" is an interesting idea esp as it relates to "go-no-go" gage"

Machtool
01-21-2013, 07:27 AM
They didn't. Most definitely they did. Didn't you read page 300 of the link YOU sent to us to, or the other direct link I provided?
Once again, Starrett say's
These full ball gages are used for general work

couldn't you people trouble yourselves to look at such items as the Starrett catalog so that you might know what you are talking about? So when the people go to the trouble and look at that catalog. Were you hoping that no one would check? On the other hand, when you look up said catalog, and you find that Starrett themselves call that style a “full ball” gage.

Would it or wouldn’t it be fair to expect, that if Starrett call it a full ball gage, that in use it would also be expected to call it a full ball gage? I know it’s not truly round. Who would you believe, Starrett or You?

It taws’t me that went out big with this one,

No such thing