View Full Version : Chatter when using my new Sinclair Premium Neck Turning Tool

07-08-2016, 11:06 AM
My new Sinclair premium neck turner arrived a few days ago. I did all the listed case prep and attempted to turn some sacrificial Winchester .222 Rem case necks. Although a nice little curl came off with a very slow pass both in and out, every test resulted in chatter marks the length of the case neck. I tried sizing the necks with different Redding neck bushings and nothing changed. I lubed the mandrel with Imperial sizing wax. The Sinclair drill type case holder was mounted in my Myford Speed 10 lathe with the back gear applied so rpm was slow (64 rpm). There are no issues with the lathe as I can cut ferrous, non-ferrous and plastics very nicely. Any suggestions as to what may be causing the chatter??

Addendum: I received a message from Brownell's just as I pressed the "post" button.
They have suggested backing off the initial pass to 70-80% of the desired cut and finish to full dimension with a second pass. They also suggested increasing the lathe speed to 200-250 rpm. I will try these and post the results. Any other suggestions are still welcome.

Further report: The finish was very much improved when I increased the rpm to 195. This brass has been fired many times so I suspect the dimpling and chatter could be caused by the hardened condition of the case. I am not happy with the significant wobble in the case when it is mounted in the holder.

Further still: I tried a few once fired Win cases and found the results to be even more satisfactory.