Turning Matching External/Internal Tapers

[mklotz]

Another way to measure a hole like the exit of an internal taper is to measure how far a precision tooling ball seats into the hole, then do a bit of mathematics to obtain the diameter of the hole.

The accuracy of this method depends heavily on the condition of the hole edge. There can be no chamfer or burs and the ball can not be pressed into the hole.

The associated math looks like this...

Let:

R = radius of tooling ball
H = distance ball descends into hole
D = diameter of hole

Then:

Z = R - H
A = 2 * ACS (Z/ R)
D = 2 * R * SIN (0.5*A)

[rgsparber]

Mrehmus2.

You have mentioned a very significant part of angle cutting.. Any tool that you use , Indicator or cutting point of tool bit must be on dead center of the lathe. Rick does this with the indicator, altho he is doing it almost subconsciously, because he has done it so often, but doesn't mention the tool point..

Otherwise, a magnificent presentation, Rick!

mr herb

I updated the article to show me first setting the cutter on center. You are right, it didn't occur to me to even mention this step.

Rick

[DIYer]

Thanks rgsparber! We've added your Matched Taper Turning Method to our Machining category,
as well as to your builder page: rgsparber's Homemade Tools. Your receipt:

Matched Taper Turning Method by rgsparber

tags: taper