Comments on: Reverse Your Rocket Tool for a Smoother Inside Neck Chamfer

By: Editor

Editor — Mon, 10 Jun 2013 03:04:30 +0000

Understand that I am NOT telling people to push hard with the tool. You are just rolling it lightly in reverse, maybe three or four, gentle 40-degree rotations, sort of floating over the chamfer. And remember we are also talking about a tool that costs about $16 bucks and will probably work better if it NOT ultra-sharp. As noted my Forster tool is working 100% fine after chamfering multiple 1000s of necks for a full decade. If I have to replace the tool after another decade of use, my tool cost will have been 80 cents a year, less than the price of one piece of Lapua brass. But the reality is that you will lose the tool to rust long before a little light back-spin is going to hurt it… at least in my experience.

By: Boyd Allen

Boyd Allen — Mon, 10 Jun 2013 02:21:29 +0000

Although I usually get some satisfaction by giving the editor a hard time is he gets some little detail wrong, this time I am jumping in on his side (no disrespect to the machinists who have posted).

As an example of the difference between chamfering case neck IDs and other more normal machining operations, about 14 years back I wrote an article about several products that are sold by Holland Gunsmithing, including a chamfer tool that has a VLD angle, and three spiral flutes that are glass beaded, over their entire surface including what started out as conventional cutting edges.

Curious about this detail, I called Darrell and asked the reason for the unconventional approach. He told me that it was done to keep the edges from digging into the brass excessively, which the edges did when sharp. Skeptical, I tried it, and it worked perfectly, producing a smooth burnished chamfer, that was easy to control. Since then he has changed cutters, but I still have the old one, and it still does just fine.

The moral, sometimes things do not work just the way that you expect them to. Rules have exceptions.

By: Nat Lambeth

Nat Lambeth — Mon, 10 Jun 2013 00:16:58 +0000

I agree with the previously posted comment. You don’t run drill bits, reamers, end mills, files backward without ruining them.

By: Terry Balding

Terry Balding — Sun, 09 Jun 2013 20:37:21 +0000

Never ran a cutting tool backwards and done anything good for the tool.

Editor: Terry, we appreciate your comment (Terry is the 2012 NBRSA Champion at 600 yards).

But the idea is not to drive the tool with heavy pressure in reverse direction. You are essentially just rolling the tool gently over the edge of the cut with almost no down pressure. I’ve done this for years with no ill-effects (on a forster rocket).

The problems I see most guys having is that they OVER-cut their chamfers or dig in the edge of the blade unevenly. Remember this is just brass… we are not talking about cutting steel with a chamber reamer. Other guys go in way too far with the deep-angle K&M, leaving a knife-edge on the case mouth, which is a bad result.