Measuring the diameter of shallow holes

DMS

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I am making some parts in delrin that involve a shallow hole 0.118" deep (3mm). The diameter is 0.866" (22mm). It's also a bearing fit (a pair of these parts fit over a 608 bearing), so I need to be pretty consistent. I am going for a fairly heavy press, as friction is all that will be holding these in place. My problem right now is measurement. I have been using telescoping guages, but the hole is so shallow, and the plastic is so forgiving, it is hard to get a consistent measurement. I'm thinking somebody out there has to have a better way.

One other thing; this is a test batch (6 pieces). If it works out, I need to make another 12. It took me about 2 hours to make 3, mainly because I was measuring 3 times after every pass before I was sure I was really "there".
 
This is a bit difficult in a soft material.

This is one of those times that I would 'trust the dials' on my machine. Once you find the the number that gives you the diameter you want, just come back to the same spot for each part. Do everything the same way each time.

Calipers do work pretty well for measuring shallow pockets. You should be able to measure to about 0.001 or better. You could also make a set of go-no go plug gauges.

I'm sure somebody will have a much better idea.
 
Indical. High resolution DTI on it.

Not sure how this would work. Unless you are talking about the depth. I guess my original question was not clear. I am trying to measure the diameter. I have a depth mic, but the depth is less critical, though my repeatability is pretty good. I do have a a couple decent indicators, a 0.0005" DTI, and a 0.001mm DI, I'm just not sure how I would configure them to measure an absolute dimension (I have only used them to measure relative dimensions)

Jim, you may be right that I should just trust my dials. I have been doing a bunch of tool changes (well, 3, face, bore, part), and have been leery of doing that. I'll give that a try.
 
The Indical is ideal for soft materials. Low measuring pressure. Don't confuse it with an Indicol. Different animal. Useful for measuring ID's, ID grooves, relief diameters, etc. I works very well for a shallow bore gage.
 
I'd use a inside micrometer for this but if I didn't have one I'd probably use either my dial calipers or make a plug gage 0.0002" undersize.
 
The Indical is ideal for soft materials. Low measuring pressure. Don't confuse it with an Indicol. Different animal. Useful for measuring ID's, ID grooves, relief diameters, etc. I works very well for a shallow bore gage.

AAAAAH Gotcha. That looks like it would work well (I have seen those before, but the name didn't jog my memory).

NightWing, I was looking for something like that first gauge in the linked pdf, but nothing like it showed up in my google searches other than hole gauges, which seem to max out at 0.5". The Indical may be more versatile overall.

I think i will press forward on the first set with Jim's suggestion. If it works out, it may be worth investing in an indial or large bore gauge for the remaining 12. Any excuse for more tools ;)
 
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