Proper gauging of tight tolerance (reamed) holes

[IRONPOORER]

I have an order for a large number of castings that need to have a through hole reamed to .2505"--.2510" and need a simple but effective means of gauging these holes.

As you cannot put the same size pin/plug guage into the same sized hole how do I guage these and not give up any of my tolerance?

If I use a a fudge factor of .0002 under (to be able to put the pin into the hole) .2503" deltronic pin as my "GO" and .2512" NO-GO?

What about taking an exact size Deltronic pin and gring a flat (.020") on two sides?

I wish I had air guages but do not, and I really need something my operators/inspectors can use as a quick check at the machine.

Thanks in advance

 

[Michael_M]

What about (broken link removed) with a .0001 indicator (this one has a .0005). This way you can also check for roundness.

I just found an image on Google. I have no idea if the company in the link is good or not (just using the pictures).

on a separate note, if the job allows for it, I would get a dedicated ring gage to set the dial bore gage. Setting a dial bore with a micrometer is a little more difficult and allows for some easy errors.

 

[Jen Kirley]

For a tolerance you describe I would favor a bore gage such as Fowler sells (I have no affiliation) with a 0.00001" resolution. See pages 154 and 155 etc. of the Fowler Catalog.

 

[dwperron]

Another possibility could be an inside micrometer.

An example of one that might fit your requirement would be:
https://www.swissprec.com/cgi/ISSRIT2?PMAKA=13-576-4&PMPXNO=25705456&PARTPG=ISLMK3

 

[wkl]

Just use a telescoping gage and 1" outside mic.
That way you don't have to buy any expensive tools.