Thread Milling Climb versus Conventional

[Geof]

I was thread milling a 2-1/4" dia., 8tpi acme in 6061 using a single point tool and trying to push things as fast as possible on speed, feed and depth of cut. With climb milling taking a full depth cut at 6000 rpm and 50 ipm I would get faint chatter marks on the thread. Under the same conditions using conventional milling the thread came out nice and smooth. My conclusion is that with climb the full width and depth of the cutting edge hits the work and causes flexing and vibration in the toolholder but with conventional the entry is gradual so there is no vibration induced.

Has anyone noticed anything similar?

[littlerob]

I have run into it no matter which way I cut the threads, but mine is because of the helix of the thread in relation to the 60° tool. But either way I would get "markings".

Robert

[djr76]

Makes sense to me, and since its single pointed, you wouldn't have to worry about chip re-cutting.