Neck turning (Getting it right the first time)

[dedogs]

With good brass, I have been able to hold .0001" thickness on the necks a good portion of the time with the K&M

I sure don't like that sharp step at the shoulder neck junction. Looks like you're going to get a neck separation eventually. What is the angle on your cutter? dedogs

 

[LHSmith]

Really?

You must be a world class machinist. Probably spent all your life making aircraft parts for Boeing right?

Why is it that its always guys with no information in their profile page that make some of the most incredible claims. Maybe some of the newbies will buy that bull, but I'm from Missouri City, Texas. You'll have to show it to me for me to believe that line.

Maybe you've been using the same micrometer that Roger at K&M uses. The one that was .0008 off from the custom mandrel that I ordered from him

Joe

As I told you before it is possible with the proper tooling and maintaining cases,cutter, and mandrel at a constant temp. AND adeptness at reading a mic.
Is 0.0001 overkill? I like to minimize as many variables as possible.

 

[Dusty Stevens]

As I told you before it is possible with the proper tooling and maintaining cases,cutter, and mandrel at a constant temp. AND adeptness at reading a mic.
Is 0.0001 overkill? I like to minimize as many variables as possible.

With the k&m its all about heat control as small as it is. I used to heat mine up in my pocket before i turned but realized it gets hotter after the first case so i put mine in a bowl of ice water for 30mins before i use it and i put it in that bowl after every case while i chamfer the mouth and it holds a tenth over the life of the cutter never having to adjust it. I get a new turning tool for every caliber and never adjust them once theyre set.

 

[T-shooter]

I sure don't like that sharp step at the shoulder neck junction. Looks like you're going to get a neck separation eventually. What is the angle on your cutter? dedogs

I think it's about 45°. I never checked it. Part of what appears to be the edge is a reflection I found another picture that a little more clear. I've thought about ordering another cutter that is profiled closer to the angle of the shoulder.

 

[T-shooter]

As I told you before it is possible with the proper tooling and maintaining cases,cutter, and mandrel at a constant temp. AND adeptness at reading a mic.
Is 0.0001 overkill? I like to minimize as many variables as possible.

Right, a more constant temperature. It also requires a snug fit on the pilot and lubrication. If the neck isn't expanded properly or is a loose fit, it will wobble producing less than ideal results. For trying to see how accurate it could be, I cut the necks a little thinner than I normally would so I could get a 360° cut. Also I use a slow speed and run 2 passes over the neck feeding the case in evenly and slowly. By hand holding, your wrist will flex if there is any misalignment with the case and the driver. I never thought it was possible to turn that close until I bought a tubing micrometer. A couple other members reported similar results and I was skeptical. The brass I tested this on was new Hornady .308 and it had been annealed and resized once. If I can find some older brass, I'll see how it does.

Probably anything over .0005" is overkill. I'm not going to worry about it and usually don't check the necks after the initial setup.

 

[dedogs]

I never checked it

I think if you section the case in the first picture lengthwise you will find the the brass at the neck shoulder junction is very thin. I agree that you should look at getting a blade that more closely matches the angle of your shoulder. dedogs

 

[T-shooter]

I think if you section the case in the first picture lengthwise you will find the the brass at the neck shoulder junction is very thin. I agree that you should look at getting a blade that more closely matches the angle of your shoulder. dedogs

Good idea. I've never had a problem with any of them. The one in the pictures (same case) was cut thinner than what I normally turn them, so I could get a 360° cut. I won't use that piece of brass to reload. I'll see if I can get another picture closer using a tripod so I won't have to use a flash.