Measuring ID

[Gordon]

What do others use for measuring the ID of things like cylinders? Also smaller bore holes like for bearings etc in the 1/4 to 3/4 range. I have been using telescoping gauges for the bigger holes but the only thing I have for the smaller holes is my vernier calipers. There are expensive solutions but most of them are not practical for a home hobby shop.

 

[Dr Jo]

I have ball gauges for holes between 3mm and 13mm. Below that I use pin gauges (or drill shanks).

The poor man's hole gauge has always been drill shanks.

Jo

 

[Blogwitch]

I'm an internal mic man myself and if that doesn't get me high enough, clock bore gauges.

One thing you shouldn't use are digital or vernier calipers for internal measurement as the nibs can't get into the correct position, plus they have flat edges so cannot give a true reading. They only give somewhere near.

Pin gauges or drill blanks is another way, but they are more expensive than buying full sets of good quality drills.

When cutting and getting very close to size I rely on Starrett taper gauges as it is quicker than using an internal mic, then use the mic for final measuring.

John

 

[Gordon]

I have been using a digital caliper to get close then use the telescoping gauge with a micrometer. Not too sure how accurate that is. The problem with using drills or dowel pins on small holes is that it only works on standard sized holes. If you want to do something like a press fit for a .375 bearing at .374 it does not work. I am thinking about purchasing an inside mic. The one which goes from .2 to 1.2 covers most cylinder bores and has round pins so it should be more accurate than a caliper at least. One problem is that it only checks on the leading end and does not tell if there is taper. The telescoping gauge at least tells me that. I am thinking that the telescoping gauge is probably almost always good for .005 and with care probably .002.

 

[purpleknif]

Check out "small hole gages". Probably a lot of them on E-Bay. Not a lot of difference between Chinese and Starret or B & S ,

 

[xpylonracer]

Like you I use telescopic gauges/mic for most internal measuring, for the smaller bores/holes I use either of the pictured gauges again measuring over the ball with a mic or vernier.

 

[Hopper]

Anything under half inch I use ball gauges and a mike. Cheap and accurate.

 

[fcheslop]

Been a tight wads I tend to make a Go no Go gauge just simply turn a bit of bar with a couple of thou steps it lets me know when Im getting near

 

[ShopShoe]

If I'm worried about the best that I can do, I do as fcheslop recommends and make a go/no go gauge.

Otherwise, I have telescoping gauges and ball gauges.

For a good real-world description of how to use the telescoping gauges, Abom79 talks about that on YouTube here:

https://youtu.be/R6YLK0F3ytc

--ShopShoe