Single pointing a thread

I am ploughing on making a metric collet. It. The thread on it is 14.45 mm max diam with a 1.2 mm pitch.When I view the thread through a microscope it has a 55 degrees with rounded troughs and peaks like a Whitworth.

So eventually I will make a tool that cuts the correct trough shape and angle, the question is how do I get the peaks rounded and at the correct diameter. If I just use an OD of 14.45mm when the thread is the correct minor diameter, the peaks will have "flats"on them so they will need rounding off.

Any ideas on a (cheap) way to go?

Frank

If I just use an OD of 14.45mm when the thread is the correct minor diameter, the peaks will have "flats"on them so they will need rounding off.

Why? Does it matter if the peaks are flat..or only slghtly rounded with scotchbrite?

They are supposed to have flat peaks.

Hi Muzzer, all very good but he said it was Whitworth form not metric.

Frank

Your thread angle is actually a Lownherz standard with an included angle of 53° 8'

I have based that on guessing you are making a Lorch type B collet for your Alexander/Deckel high speed milling head.

I have an original drawing of these collets, if you want a copy PM me.

Phil

Edited By Phil P on 18/04/2016 22:34:00

Many Thanks Phil, you jogged my memory, I think it was you who sent me the drawing about three years ago (Crawford Lorch collet). Interestingly the thread form is shown with flat peaks and troughs which on all of mine, as said are nicely(?) rounded. It does simplify cutting the threads, just have to do a bit of maths to calculate the actual dimensions, as opposed to the measured ones.

Frank