Inside Mics

[Bob La Londe]

I've got a .2 to 1.2" inside import mic and I've been pretty happy with it. It's better and more consistent than any of my calipers. I've been thinking about picking up a 1-2 and a 2-3. These are NOT tri mics. Nor are the straight inline barrel mics. They are like external mics. Anything I should be aware of?

[JRouche]

I've got a .2 to 1.2" inside import mic and I've been pretty happy with it. It's better and more consistent than any of my calipers. I've been thinking about picking up a 1-2 and a 2-3. These are NOT tri mics. Nor are the straight inline barrel mics. They are like external mics. Anything I should be aware of?

I dont like to give other advice but... I dont like those tools for bore measurements. I have measured many bores under 5.0001" with success using a "snap" gage.

You know. The key with those, is consistency. With the user, never the tool. The tool is just that. Its not a "magic" tool. Its a tool to help the user get what they need.

I snap gauge, lock, then Mic. JR

[Alan Smith]

I think Mitotoyo refer to those as calliper type inside micrometers. I can't make up my mind about them. I bought a cheapish version to try before splashing out on a Mitotoyo. I do quite like it, however on balance I find I'm using my telescopic gauges in preference.

[macona]

I use telescoping gauges as well and take several reading to make sure it is right, its real easy to get it wrong. I just don't do enough stuff with internal tolerance that need anything more then telescoping. Dont use calipers, they have flats on the edges which is enough to throw the measurement off enough to go from what should be a sliding fit to loose.

[ATW]

I tend to use my import inside micrometers more than snap gauges as it is a "direct" measure rather than a "transfer then measure" one less step for me to mess up.

When I first got them I did do comparative tests between them and snap gauges as a sanity check. The correlation was very good, so I guess my technique must be equally bad with both!

They are limited to the depth into the bore you can measure (my 5~30mm set it something like 5mm) so if you need to get further in than that the snap gauges come out.

[Bob La Londe]

Its funny. I do have a set of snap gages, and I never even think about using them. They are even in the tool cart I currently use at the lathe.

[dian]

at least the telescopics are cheap. the most exact measurement of id i practice is to drop the part on a grinding mandrel (if the size is not some weird number). you see 1µ easily.

[eKretz]

I use bore gages for anything that's got fairly tight tolerance. Telescoping gages can be used to closer than .0005" but it's time consuming and requires a lot of care in use. Bore gage is quick and easy to use once set up. Pin gages are a good double check but won't show some out of round conditions or a reverse bellmouth (barrel shape) very well for instance. They also don't quantify error.

[Rich Carlstedt]

I don't use Inside Mike's or Telescopic Gauges unless it is a short bore , or C/Bore and I do not have Dial Bore gauges
I use good Adjustable Parallel Gauges -- and have used them for over 50 years
You expand the parallel in the bore and measure Cross Corner for bore size !
They offer these advantages over the above bore tools:
You use the same OD Mike that will measure the mating part
No standards or transferring measurement from one mike to another mike ( Error !)
A tapered bore is readily apparent as the parallel can move at one end
This method will also detect "Coke bottle" Bores
"Oval" bores can be detected by rotating the parallel
Easy method for bore work without having to develop "Bore Feel" ( which is a real skill)

"Good gauges" means, smooth surfaces and adjustment with no dings and constant sharp radius on the edges....and of course, Parallel in nature on all sides !

Flung Dung parallels do not cut it

Rich

[Bented]

Like so? https://www.mscdirect.com/product/details/06235592
My experience with such tools is that it takes a good deal of feel to achieve repeatability in use but will perform better then a caliper.

You like to chase tenths so they are probably not the best choice in your case.

[tom_d]

I've got a .2 to 1.2" inside import mic and I've been pretty happy with it. It's better and more consistent than any of my calipers. I've been thinking about picking up a 1-2 and a 2-3. These are NOT tri mics. Nor are the straight inline barrel mics. They are like external mics. Anything I should be aware of?

Only problem with inside mics is that they are micrometers, and therefore subject to calibration errors. I have several fairly complete sets that go up to 12 inches with interchangeable anvils. To bypass any calibration errors I use them as I would a set of telescope gauges. That is, I set them by feel. Advantage with the inside micrometers is that I can get a visual reading before removing the mic from the part. From there I confirm the reading while measuring with an outside mic that's been set to a known standard. Very easy for me to get accurate measurements that way, and I don't have to be concerned that the larger set of mics is an import of "lesser" quality.

[dalee100]

Hi,

I've got a .2 to 1.2" and a 1.2" to 2.2" mic. I find them handy for measuring slots and keyways. Not so much holes. They can tell you about the very top edge of the hole, but you can't survey a bore with one.

Snap gauges are slow to use and errors are too easy to make some days.

Dial Bore Gauges can be a pain to set, but fast to use once set and can tell you much about a bore. Best for a survey of a bore.

The adjustable parallel trick will not tell you about a tapered or stepped bore and is limited in reach.

I own them all and use them all. But no one tool is best in all situations. Choose your tool wisely.

[Bob La Londe]

Like so? https://www.mscdirect.com/product/details/06235592
My experience with such tools is that it takes a good deal of feel to achieve repeatability in use but will perform better then a caliper.

You like to chase tenths so they are probably not the best choice in your case.

Yes sir. Pretty much like that. I only chase tenths when making a tool used for setting up jobs or cutting. Often even for those it's not all that necessary. Most of the rest of the time I'm happy if the parting line doesn't show too badly.

[Fasturn]

I don't use Inside Mike's or Telescopic Gauges unless it is a short bore , or C/Bore and I do not have Dial Bore gauges
I use good Adjustable Parallel Gauges -- and have used them for over 50 years
You expand the parallel in the bore and measure Cross Corner for bore size !

Rich

I have done this, but use 2 dowel pins top and bottom of the parallel. Then Mic over the dowel pins. This is in a pinch!

IntermIc 3 leg , after setting with master is fast and accurate.
deltronic gage pins are the best way to hold .0001 on a bore.

[dian]

I don't use Inside Mike's or Telescopic Gauges unless it is a short bore , or C/Bore and I do not have Dial Bore gauges
I use good Adjustable Parallel Gauges -- and have used them for over 50 years
You expand the parallel in the bore and measure Cross Corner for bore size !
They offer these advantages over the above bore tools:
You use the same OD Mike that will measure the mating part
No standards or transferring measurement from one mike to another mike ( Error !)
A tapered bore is readily apparent as the parallel can move at one end
This method will also detect "Coke bottle" Bores
"Oval" bores can be detected by rotating the parallel
Easy method for bore work without having to develop "Bore Feel" ( which is a real skill)

"Good gauges" means, smooth surfaces and adjustment with no dings and constant sharp radius on the edges....and of course, Parallel in nature on all sides !

Flung Dung parallels do not cut it

Rich

but it still depend on how strongly you press them into the bore. surface finish.