Neck turning

[Lkwebb]

I'm starting to neck turn more brass for my 6ppc which is a .269 chamber. I have necked turned one batch of brass awhile back to get me goin. I did them in 2 passes but I know now 3 is probably better for consistency all around the neck. I unfortunately turned the first batch at a to fast rpm ( but have had good groups). I'm shooting for .010 to .0105.
I ordered a new drill that has 2 speeds and the lowest being 400 rpm.
My main question is if I take 6 measurements of my turned brass but I have for example .010 .0105 .011. .010 .010 and .095.
Do I scrap this piece of brass cause of the. 095 being under my main measurement being .0105 to .010.
I am assuming all measurements need to be as close as possible to my set goal measurement. Of .0105 to .010.
Please correct me and give me some positive advice lol

 

[bored184]

I've pondered this question myself because my 308 palma rifles requires neck turned brass. I'd mark that piece of brass and shoot it mid string when your not in a match and see where it goes. Let the target tell you if it's a problem.

My 308 shoots very well and the brass I use was my second ever time turning brass. First time I had help and guidance. The second time was solo.

 

[Lkwebb]

I've pondered this question myself because my 308 palma rifles requires neck turned brass. I'd mark that piece of brass and shoot it mid string when your not in a match and see where it goes. Let the target tell you if it's a problem.

My 308 shoots very well and the brass I use was my second ever time turning brass. First time I had help and guidance. The second time was solo.

Well the first batch I turned has done me well, I have shot some groups in the .200 range. I m pleased with those types of groups considering I have only been shooting 6ppc for a year and still learning.

 

[Bronsin]

If you have a difference of .0015 in thickness on the same piece of brass after neck turning, having a thin spot at .0095 is the least of the problems. There should be no variance in thickness after being turned once, much less 2 or 3 times. What are you measuring with?

 

[Lkwebb]

If you have a difference of .0015 in thickness on the same piece of brass after neck turning, having a thin spot at .0095 is the least of the problems. There should be no variance in thickness after being turned once, much less 2 or 3 times. What are you measuring with?

Tube Micrometer Reloading Ball Spherical Anvil​

 

[Lkwebb]

I'm also using the 21st century neck turning lathe

 

[Petros284]

200-300 RPMs is an optimal speed while turning brass. It helps keep temperatures down and in turn enhances precision while turning. Be sure to use a good lube with any mandrel to aid in the process. Shooters Choice FP-10 is a good one to go with.

 

[BoydAllen]

I am always mystified when I read of big turned neck discrepancies. It really isn't that hard. One tip worth remembering (for your finish cut) is to feed to the shoulder very rapidly, making a nasty cut, that leaves a lot of material and then come back to the mouth very slowly, and not go back. If you let the case and turner float so that you are not trying to force things straight, the cutter will keep the neck tightly pinned to the mandrel. When you go back the neck can pull away from the mandrel and screw up your uniformity. Another issue is the whole thing about needing a press on fit. All that does it create unnecessary heat problems. After the finish cut, before you take the case out of the power adapter, grab the neck with a wad of 0000 steel wool and fast spin it for a couple of seconds. My necks are better than +-0001, usually half that. You need a good lube, low RPM, and a carbide mandrel.

 

[Petros284]

I'm also using the 21st century neck turning lathe

There is some fine tuning you can do while using the lathe. Like I mentioned earlier speed is important and as is feed rate. Keep your feed rate steady and consistent. Do not overtighten the screw that holds the neck turning tool on to the L-Bracket. You want this to loose enough to free float without rotating while in use. Ensure that the rubber spacers between the NT tool head and the are not compressed either. In your neck turning tool head itself make sure the rubber washer is affixed to the back of the cutting tool assembly alignment screw. If it has fallen out in the tool or is missing it can cause some variation in results.

Give me a shout if I can be of any assistance.

 

[Petros284]

I am always mystified when I read of big turned neck discrepancies. It really isn't that hard. One tip worth remembering (for your finish cut) is to feed to the shoulder very rapidly, making a nasty cut, that leaves a lot of material and then come back to the mouth very slowly, and not go back. If you let the case and turner float so that you are not trying to force things straight, the cutter will keep the neck tightly pinned to the mandrel. When you go back the neck can pull away from the mandrel and screw up your uniformity. Another issue is the whole thing about needing a press on fit. All that does it create unnecessary heat problems. After the finish cut, before you take the case out of the power adapter, grab the neck with a wad of 0000 steel wool and fast spin it for a couple of seconds. My necks are better than +-0001, usually half that. You need a good lube, low RPM, and a carbide mandrel.

Good advice Boyd! The Black Nitride coated arbors work pretty darn well too!

 

[6MMsteve]

Good stuff here

 

[Mulligan]

Unless you make a living with a mic, measuring case neck thickness with a ball mic can be skill that has a short shelf life.
In other words, just because you have measured the case in six different places and got a wider range of results than you would like to see, doesn’t mean that is true, again, unless you are very skilled with a mic.
Put a sharpie mark on the case neck and measure the exact same spot a dozen times and see it all come up the same.
You are using good tools, I’ll bet you are closer than you think.
CW

 

[Lkwebb]

Good advice Boyd! The Black Nitride coated arbors work pretty darn well too!

Unfortunately I didn't get the black nitride when I ordered.

 

[Bronsin]

Tube Micrometer Reloading Ball Spherical Anvil​

The reason I ask is because some mics have a friction thimble, some have a ratchet, and some have nothing at all, requiring you to feel the same amount of force to take a reading. They can be very different. Some people have a very light feel, others treat it like a graduated c-clamp.

I also keep the RPM low, but that's come from trial and error. I spun it too fast, with a lube that didn't work very well, on a plain steel mandrel. It heated up, and since the cutting tool didn't move, it cut the neck way too thin. Oh well. School of hard knocks.........

 

[Lkwebb]

There is some fine tuning you can do while using the lathe. Like I mentioned earlier speed is important and as is feed rate. Keep your feed rate steady and consistent. Do not overtighten the screw that holds the neck turning tool on to the L-Bracket. You want this to loose enough to free float without rotating while in use. Ensure that the rubber spacers between the NT tool head and the are not compressed either. In your neck turning tool head itself make sure the rubber washer is affixed to the back of the cutting tool assembly alignment screw. If it has fallen out in the tool or is missing it can cause some variation in results.

Give me a shout if I can be of any assistance.

I guess I did have it a lil to tight, I loosened it up and it seems to give me better measurements.
Thanks gentlemen...

 

[Lkwebb]

Guess all I wasted was 6 pieces of brass...

 

[Webster]

I am always mystified when I read of big turned neck discrepancies. It really isn't that hard. One tip worth remembering (for your finish cut) is to feed to the shoulder very rapidly, making a nasty cut, that leaves a lot of material and then come back to the mouth very slowly, and not go back. If you let the case and turner float so that you are not trying to force things straight, the cutter will keep the neck tightly pinned to the mandrel. When you go back the neck can pull away from the mandrel and screw up your uniformity. Another issue is the whole thing about needing a press on fit. All that does it create unnecessary heat problems. After the finish cut, before you take the case out of the power adapter, grab the neck with a wad of 0000 steel wool and fast spin it for a couple of seconds. My necks are better than +-0001, usually half that. You need a good lube, low RPM, and a carbide mandrel.

Don't understand why people like titanium carbide coated bushings and mandrels. The TiC is just a hard coating, same dimensions.

 

[PracticalTactical]

I have never ever had a problem with inconsistent neck wall thickness after neck turning...

So this brings me to the question of what method is being used to turn necks. I also bring in to question what is being used to measure the variance in neck wall thickness... If its a Vernier.. that is your root problem. The error is in the accuracy of the Vernier itself rather than the brass. As stated above, you need a pin mic or a ball mic.

I will say that to neck turn well requires a certain feel for it.

I cannot speak for others, but my process compensates for the stress induced during the neck turning process which enlarges the neck diameter.

My starting neck mandrel is always smaller than the mandrel I use for the second pass. Mandrels always fit snug, but never tight. I only use carbide mandrels.

I have never felt a need for a third pass, as suggested above.

If you are using a drill and do not apply constant pressure toward the mandrel and away from the cutter, you can affect the wall thickness if the brass fits loosely to the mandrel.

 

[Dave M.]

I'm starting to neck turn more brass for my 6ppc which is a .269 chamber. I have necked turned one batch of brass awhile back to get me goin. I did them in 2 passes but I know now 3 is probably better for consistency all around the neck. I unfortunately turned the first batch at a to fast rpm ( but have had good groups). I'm shooting for .010 to .0105.
I ordered a new drill that has 2 speeds and the lowest being 400 rpm.
My main question is if I take 6 measurements of my turned brass but I have for example .010 .0105 .011. .010 .010 and .095.
Do I scrap this piece of brass cause of the. 095 being under my main measurement being .0105 to .010.
I am assuming all measurements need to be as close as possible to my set goal measurement. Of .0105 to .010.
Please correct me and give me some positive advice lol

How are you measuring? I bet the variation you are seeing is likely in your measurement setup. What neck turning setup are you using?
Dave

 

[Lkwebb]

How are you measuring? I bet the variation you are seeing is likely in your measurement setup. What neck turning setup are you using?
Dave

21st century neck turning lathe and a powder drill.
I think we figured out the issue was I had the cutter tool and mandrel to tight on the frame and it wasnt able to free float so to speak