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Countersink measuring tools??

DMK

Plastic
Joined
Jul 6, 2011
Location
Tennessee
I need to measure the diameter of a countersink and document the size on a first article. I usually use countersink measuring tools, but this one has detail standing around it that makes it impossible for the tool I have to sit flat.

As shown in the picture below it’s a .210” hole that requires a .254 (+/- .005) Dia 90 degree countersink. A .500 diameter is cleared away from the ribs around the hole.

I would need a countersink measuring tool that could measure that diameter, and the diameter of the tool body would be less than .500”. Anyone know if there is a countersink measuring tool that would fit and could be used on the shop floor?

Countersink.jpg
 
We use a ball that sits on the angle part of the countersink, meaure the distance from the high point of the ball to the flat surface (usually through a ring that goes around the ball with a depth mic), then do the math. Of course you have to measure the angle of the cutter and assume your countersink is at the same angle. Cheap and accurate, but it takes time and talent.
 
I use gage balls all the time for various tapered holes. Just be sure that the ball size is such that it actually contacts the chamfer, and not just the tangent point to the through hole.
 
...or a ball and indicator while still in the machine..
I would be concerned about using an indicator to measure the heights of two balls of different diameters accurately.

The indicator has a spherical measuring face. Matching this accurately to the center of the two different balls of interest might be a challenge, particularly if the taper is not precisely circular at the points of contact.

- Leigh
 
we usually draw it up mastercam
use a gauge ball of appropriate dia.
put gauge ball in chamfered hole.
use a interapid indicator and indicol
find highspot on gauge ball
o indicator on high point of gage ball ( write height position down on paper)
touch indicator off on plate.
write down position at the part surface and subract one from the other, giving your total height of ball from surface..

you can offset in mastercam to give you a +/- tolerance at depth.. takes about 10minutes to draw it up.. you'll be within .0005
 
Thanks for all the replies. I ordered gage balls that will sit midway in the chamfer, I have a drill bushing ground flat to a know length that is placed over the ball. I use a depth mic to make the measurement. Seems to work.
 








 
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