Neck Turning w/ Sinclair premium tool

[phlegm]

I've got the "Turning" and "Expander" mandrels for the 6PPC.

In ignorance, I turned a few pieces with the Expander in place, and everything seems to be nice and consistent.

Why would I need to expand the necks with the Expander mandrel, then turn them with the Turning mandrel, especially if everything is working well as I've done it?

 

[dkhunt14]

The turning mandrel is usually about a .001 smaller then the expander mandrel to allow for springback and give a tight fit to turn. It should do a better job. Matt

 

[dcali]

If it works it works. I usually turn without using the expander fist. Too loose is worse than too tight, and as long as you're not generating too much heat, you're good. Carbide turning mandrels are definitely worth it, by the way.

 

[Brians356]

I've got a few Sinclair expanders which are only .0008" under bullet diameter, so depending on brass spring-back and the actual diameter of the turning mandrel, it could be even more on the loose side.
-

 

[phlegm]

If it works it works. I usually turn without using the expander fist. Too loose is worse than too tight, and as long as you're not generating too much heat, you're good. Carbide turning mandrels are definitely worth it, by the way.

This is pretty much what I figured, though my confidence wavered after reading more from the Sinclair site. It make sense that turning with the tighter mandrel can reduce the amount of error allowed.

I'm still turning by hand, so heat is not an issue.