Neck Turning - Easier than I thought

[dnellans]

Been reading for several years info here has helped me diagnosing and dealing with doughnuts, peened case ends, and other various issues that pop up as you reload cases 8+ times. Thanks for that guys.

Was considering a mini lathe but decided to buy a dedicated 21st century power lathe instead just for brass (for now). Already had tube mic’d starline, hornady, and alpha brass to see what variance looks like, and honestly I was skeptical about being able to turn to 2/10,000 or better considering a buddy’s results with a different turner and some cases I sent off to another member who offered to turn them for me.

I have to say, I am more impressed with the results, it’s far less harrowing, and faster than expected to turn 100 on the 21st lathe.

I got tinitride mandrels and am just using some standard cutting and tapping oil (for anyone wondering).

Almost all my Alpha cases are within one thou variance to start which is why I never bothered before but it’s neat skimming them 1-2/ten thou at a time to see how much and where the variance actually is!

I decided to take what amounts to about 6 ten thou off the “average” case which still leaves a few low spots on most and leaves them at 14 thou. Taking too much and thinning the necks more makes me nervous (probably needlessly), maybe in the future I’ll go thinner on a new set of cuts to uniform every neck all the way but this is clearly a big improvement to start with on the cases as I get comfortable.

I started on some old brass with bad primers just in case, but even the first four I did would be usable IMHO! Pic attached.

I did notice that as the mandrel heats up it absolutely expands a bit. Turning the 1st case again after 10 in a row takes just a hair more off. Certainly not more than 2/10,000 but something to think about if ultimate precision is the goal.

Thanks for all the advice guys, I hope it shows up on target!

 

[Straightshooter1]

I decided to take what amounts to about 6 ten thou off the “average” case which still leaves a few low spots on most and leaves them at 14 thou. Taking too much and thinning the necks more makes me nervous (probably needlessly), maybe in the future I’ll go thinner on a new set of cuts to uniform every neck all the way but this is clearly a big improvement to start with on the cases as I get comfortable.

I had the same concern when I started turning necks and did as you've done. Since then, I've gone further where I'm down to .0132 for my .308 cases. It's been helping with neck tension and when inspecting the fired cases, the necks look like they've provided a very good seal reducing the carbon coating on the neck and nothing migrating down to the shoulder. So, you might consider going a little thinner to get all you your neck as uniform as possible.

 

[joshb]

Always fun the first time with a new toy....I mean tool..... I honestly can’t remember when it turned into a chore. Welcome to neck turning!

 

[jepp2]

but decided to buy a dedicated 21st century power lathe instead just for brass (for now)

You bought well. I have a growing collection of 21st Century products, and am extremely happy with all. But I haven't sprung for their power lathe (yet).

 

[Shooter13]

You bought well. I have a growing collection of 21st Century products, and am extremely happy with all. But I haven't sprung for their power lathe (yet).

I had the manual one for a year or so and when they came with the power unit it was a "must have" so I sold the first and now am very happy with my XXI turner!!

 

[nmkid]

Honestly, in the whole loading process, I enjoy neck turning the most.

 

[dnellans]

There is definitely something cathartic about watching the teeniest brash shavings come off.

I played a little bit more and decided to take the first 100 down to .0137 rather than .0140 which took just a shave more off. Didn't take too long since I hadn't washed cases after oil and didn't re-oil them to turn this morning. Next 200 (to make the 300 set I'm working through) will all be at .0137 as well.

I'm putting a drop of cutting oil on the outside of the neck and the mandrel before each case, which I bet is more lube than most guys are using. Its certainly a lot more than I see any youtube videos using. I don't see any downside however with a paper towel underneath to catch the dripes and it seems makes heat a non issue after the first 2-3 cuts to get it up to temp. According to the IR gun (which might have trouble with TiNi reflectivity) the temp didn't vary more than a degree or two the couple times I felt like checking it over 40 minutes.

Aside from straightshooter1 (.0132) how thin are you guys going on your necks to try and get 100% cut on all necks versus leaving say XX% as low spots? How thin is too thin?

While turning, I also started wondering. Everyone is gaga over dashers currently...

You hear people talking about how they're "inherently accurate", with no reasoning behind it. Perhaps everyone thinks they're accurate because by the time you've fire formed, turned, and trimmed each and every one of your cases you've simply got some really nice uniform cases?

 

[David Christian]

@dnellans, are you lubing the insides of the case necks as well as the turning arbor? Adding a small amount of case lube to the arbor every few cases should help to keep the heat down as well as provide for a smoother cut. You might want to consider steel wool on the outside of the cases post turning. I slightly back the neck away from the cutter and while the case is still spinning and supported by the arbor, run a small piece of steel wool over the outside of the necks. Post neck turning I will also spin a nylon brush wrapped in steel wool on the insides of the neck. Cleans them up nicely.

DC

 

[dnellans]

Thanks for the tip @David Christian.

I'm putting a drop of oil on the outside neck, smearing it around the neck with my finger and then sort of scraping the excess oil on my finger into the case mouth to get a bit in there. A drop on the arbor near arbor ogive so that it also ends up "in" the mouth of case too. I've think I've got plenty of oil in/out since I'm doing it every case that the shavings all come off wet and the backwards pass is just a nice oil slurry cleaning up the initial cut. Its also enough oil that I have to wash the cases in some dawn, and dry em out, its clearly too much oil to just vibrate off.

I've done 200 now (100 to go) and I'm still extremely happy with the cut quality and consistency. I thought about the steel wool having seen that before but honestly, the cuts are so good after a firing you'll never even notice a machining mark is my guess. These all happen to be 3x fired cases that I F/L sized and then expanded (didn't want to start on brand new brass) so the inside of the necks have some carbon, which makes a nice slurry and they're self honing on the mandrel a bit so I'm not worried about the inside for these.

Say hi to Erik for me - the next set of new cases I'm going to turn are destined for a borden mountaineer build he convinced me was worth doing over dinner one night at a PRS match =)