[4]

Measuring Large Small Holes

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

RJSakowski

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Feb 1, 2015
Messages
3,636
Likes
4,226
#1
When measuring the diameter of small holes, my favorite tool is a pin gage. I have sets up to 1/2" but yesterday, I needed to measure a .903" hole. Ideally, I would have a full set of pins to 1" but at somewhere near a $700 even for an import set, that's an expensive bunch of metrology. I used a .500" pin and a .403" pin side by side to make the measurement. It worked great. A .500" + a.402" was loose, a 500" + a .404" was a no-go, and a .500" + a .403" was just snug.
 
Last edited:

Tozguy

Active User
H-M Supporter - Gold Member ($25)
Joined
Feb 15, 2013
Messages
1,734
Likes
1,127
#2
Typo on the no go?
 

Ray C

H-M Supporter - Sustaining Member
Staff member
H-M Platinum Supporter ($50)
Joined
Nov 16, 2012
Messages
5,215
Likes
1,436
#4
RJ,

How about a telescoping gage? Man, I love those things and get a lot of mileage out of them.


Ray
 

westsailpat

H-M Supporter - Gold Member
H-M Supporter - Gold Member ($25)
Joined
Feb 14, 2016
Messages
599
Likes
359
#5
Tri mic , they are expensive and limited range but nice .
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,585
Likes
1,897
#6
Another choice is Brown & Sharpe tapered hole gages; one side is radiused, the other flat; they are used in pairs flat side to flat side and wedged into the hole with one end protruding from the hole and measured with a micrometer other options are small hole gages, telescoping gages and inside mikes. I also have a set of B&S flat plug gages, 3/8 to 2" by 1/16ths, good for detecting taper and fit in nominal size holes.
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,585
Likes
1,897
#7
Tri mic , they are expensive and limited range but nice .
The only Tri Mic (Made by B&S) that I am aware of is a OD micrometer with three contact surfaces and is used to detect 3 lobed out of roundness and diameters of 3 or 6 fluted of end mills; Is your post of something entirely different?
 

Tony Wells

Platinum
Registered
Joined
Jan 22, 2011
Messages
7,052
Likes
2,131
#8
Intrimik I believe, John.
 

benmychree

John York
H-M Supporter - Gold Member ($25)
Joined
Jun 7, 2013
Messages
2,585
Likes
1,897
#9
Intrimik I believe, John.
Intrimik I believe, John.
OK, that makes more sense; both are B&S products Intrimics are quite expensive even used and of quite limited range I see lots of them on E Bay and wonder if they ever sell them at the (wished for) prices. They are not a tool that the average machinist or even tool maker would be able to afford; I'd think only an inspection department of a wealthy company or the government would have bought them.
 

Tony Wells

Platinum
Registered
Joined
Jan 22, 2011
Messages
7,052
Likes
2,131
#10
They are quite handy for catching 3 jaw eggs on thin parts. I've got a couple stashed away someplace. But then, I was allowed to clean out some instruments from a company I worked for. I have a few things most hobbyists and even smaller shops aren't likely to have (Ultrasonic thickness mic, anyone? Profilometer?). I didn't get everything I wanted, but some interesting stuff nonetheless.
 

magicniner

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Oct 21, 2017
Messages
443
Likes
391
#11
Telescoping gauges are very useful and not too expensive for a decent set.
You can often pick up a good bore gauge kit second hand for reasonable money, I found a good Baty kit for under £20 last year.
I have an internal micrometer of this style but not this brand - http://www.chicagobrand.com/help/inside_micrometer_files/image002.jpg - which came with a setting ring, allowing you to set it and to practice your "feel", it gives very good results at the bore opening.
Higher cost but brilliant are Diatest individual bore gauges and kits, they occasionally come up at reasonable prices (at least comparatively so for what they do), over a several years I managed to pick up a few sets for an average price around £60 along with extension and adaptor kits.
 

Redmech

Active Member
Registered
Joined
Jan 14, 2014
Messages
160
Likes
176
#12
Saw a video of a guy using rectangular gage blocks in the center with round gage pins on the ends to measure larger internal diameters, very slick method to measure internally to a very high degree.
 
[6]
[5] [7]
Top