Starrett telescoping gage repair?

[mikey]

Bore gauges and internal micrometers - good stuff but a pain to use when the work is in the lathe. Mill use is not as much of a pain IF you have enough room in Z but it takes some time. Gave both my Alina bore gauge and Mitutoyo internal mics away and don't miss them but if I had to show that I used a certified gauge then yes, I would have them still.

Inside micrometers are good for boring when tolerances are in the thousandths and are really fast to use. When the work is in the machine and tolerances are in the tenths, I pull out the telescoping gauges.

Reading a bore takes good technique with reliable instruments. Boring precisely is an entirely different matter.

 

[electrosteam]

Telescoping gauges are common in eastern Australia.
John

 

[CluelessNewB]

Doubleboost in the UK uses one in this video (near the end at about 23 minutes)

 

[EmilioG]

Using these telescoping gages to measure a bore and then reading it on a mic takes a little practice.
I bought a few ring gages to work out my technique after discussing it with Mikey and sure enough,
it's a bit tricky.

 

[Rustrp]

They use ID mics. Bore mics too but they are expensive & the average hobbyist don't own them. Funny cause I do have an ID mic but I never use it, I just use the snap gages.

I understand the ID mics and bore mics but I got the impression from some of the comments that the telescoping gauge was used much less in other countries. Maybe this was just opinion.

 

[mikey]

Using these telescoping gages to measure a bore and then reading it on a mic takes a little practice.
I bought a few ring gages to work out my technique after discussing it with Mikey and sure enough,
it's a bit tricky.

Not tricky if you have a micrometer stand!

 

[darkzero]

Not tricky if you have a micrometer stand!

That's cheating! I don't use my micrometer stand for that but it is very useful. Speaking of which, the HF micrometer is pretty damn nice for the money.

I purchased it years ago cause I needed it right away withbthe intent to get a better one later. Well that never happened cause I'm pretty happy with it.

 

[darkzero]

I understand the ID mics and bore mics but I got the impression from some of the comments that the telescoping gauge was used much less in other countries. Maybe this was just opinion.

Yeah, maybe so. As I mentioned and aside from Ken & China, I just heard one person saying they were not popular (in Germany). Maybe only not common in most or some countries that use metric? I have no idea.

 

[Bob Korves]

The technique that works for me is first having the gage set to the proper tightness, just tight enough to keep from losing the setting while transferring the reading to the micrometer. Next, the gage is introduced to the bore from the most comfortable approach possible, fixed or larger side of gage against bottom or close side of hole, inner plunger at top of hole, gage dead vertical in bore. Rock the gage gently as the upper (inner) plunger makes contact with the bore so they become 180 degrees apart in the bore. Then, carefully and smoothly swing the handle downward with the handle kept in the plane created by the sweeping upper plunger. Everything must promote the gage exactly bisecting the bore. Then comes the reading of the gage against the mic, which must be in the middle of both anvils at once, with just a small patch of anvil giving a light but consistent drag, more like a "nick" than a slide. If a stronger drag occurs, start over, the setting may have slipped. I hold the larger plunger against the fixed anvil of the mic. Testing with a ring gage like Emilio was doing is a good idea, but deeper cylinders must be learned as well, and it must be practiced on the mill and on the lathe and in other more difficult positions. If it does not feel perfect sweeping the bore, do not even attempt to measure it, do it over. If I cannot comfortably gage the hole with the gage vertical, which is sometimes unavoidable, getting good results becomes more iffy. Achieving a comfortable position at some point takes over from insisting on vertical. Bottom line: practice, practice, practice, and find out what works best for you.

 

[Bob Korves]

Especially at first, until you get repeatable results that give confidence, measure multiple times, not for an average, but for consistent results to within a couple tenths. Do not look at the mic dial until you are done measuring. It is very easy to get outlier results while starting out, later on you will be able to predict them at times.