Question about inside calipers

[markba633csi]

After struggling without any for years I've decided to shop for a couple, the plain type that are used in conjunction with an outside micrometer. Is there any advantage with the round leg style vs. the flat leg? I'm needing to measure between about 5/8" and 1"
Seems like the round leg might be a little more prone to bending? I know they need a delicate touch to give accurate results
-Mark

 

[Ulma Doctor]

i surmise the rounded leg can get around protrusions the straight leg counterpart may not be able to reach

 

[BladesIIB]

Mark, I don't think it makes a difference on the leg shape. I believe either will be rounded on the tip, which is really all that matters as you try to get the right feel through your bore. For a small hole, I think you would be much more accurate with a telescopic gauge? The only time I used inside calipers was when I was line boring and had to measure around the bar without taking it out each time. Even then, I would always double check after removing the bar with an inside micrometer. You can get pretty good with inside calipers but on a 5/8" hole it may be tricky. Just my thoughts, good luck.

 

[Forty Niner]

Hat's off to you Mark for knowing how to use inside calipers! A lot of people would struggle to get accuracy with them. Your question as to flat leg or round leg, I prefer the flat leg for the reason you suspected. Because of the stiffness. The condition of the tips is also very important. Because "feel" is so important, I think I would only buy or use trusted brand names.

 

[mikey]

Just an opinion but for measuring in the thousandths you are much better off using an inside micrometer. Calipers are very much a user-dependent thing and repeatable measurements can be iffy.

 

[benmychree]

For the hole size you are working with, round or flat leg makes little difference; more important would be leg length, for small holes, a short leg length would be best, like about 3". This makes to curved end of the leg small enough offset to fit in small holes and also the short length makes them well balanced for accurate feel. The round leg calipers are generally called "Toolmaker's pattern"

 

[Packard V8]

Just an opinion but for measuring in the thousandths you are much better off using an inside micrometer. Calipers are very much a user-dependent thing and repeatable measurements can be iffy.

What brand and model of inside micrometer are you recommending which will measure smaller than 1"? Those I've used start at $300 and up.

jack vines

 

[benmychree]

The only thing that I have seen in that category is an inside micrometer made by Starrett and B&S at least in the past, it had inside nibs like a vernier caliper. The B&S was a #250. The minimum measurement was .200", Starrett made two sizes very similar to B&S, 700 A and 700B with the same minimum measuring size of .200". Really, using dial calipers or telescoping gages are way more practical than other means, also there are small hole gages that measure smaller features than telescoping gages.

 

[markba633csi]

I think John's answer is what I was thinking also- a shorter caliper like a 3 incher, maybe Starrett.
Last time I used one was 50 years ago in high school. Probably will get telescoping gages too but anything is better than nothing which is what I have now. I've been limping along with my dial caliper but it's time to get serious about inside measurements, and I have some coming up
-M

 

[mikey]

What brand and model of inside micrometer are you recommending which will measure smaller than 1"? Those I've used start at $300 and up.

jack vines

Starrett, B&S and Mitutoyo make good ones that measure from 0.2 - 1", 1-2", and so on. They are direct reading, typically in the thousandth range. Quick to use with the work in the lathe. Not as potentially accurate as bore gauges or internal mics but good enough for most hobby jobs.