21st Century Neck Turning Tool

[Bc'z]

Just some food for thought. We (21st Century) have some lathe upgrades that are coming out to minimize any binding from excessive wobble. In testing these have shown great results! We have recently been adding these to the power lathe and soon the standard lathe. We also will be offering these upgrades as a kit for those who already have lathes. These upgrades are going to be added to the driver assembly and the Neck Turning tool.

The number one issue that can happen with the lathe set-up is the Neck Turning tool is too tight on the L-Bracket.

One thing that NEEDS to be done with the lathe when you are using it is to be sure the Neck Turning tool is loose enough on the L-Bracket not to bind up. Not loose enough to rotate when turning brass though. If the tool wants to rotate, a little pressure from the left hand on the tool will help. There is a “feel” to the setup of the tool and if it binds you will feel it. Loosen the Neck Tool on the bracket until it doesn’t feel like it binds.

Feel free to email me with any concerns or questions. Pete@21stcenturyshooting.com

I'll be calling you once I have Turner in hand.

 

[quest450]

a nice youtube video would be really helpful, the Brit is great but lacks the finer details

 

[Petros284]

a nice youtube video would be really helpful, the Brit is great but lacks the finer details

These are in the works!

 

[mikecr]

The way to mitigate cutting issues (potentially) from wobbling, is to free float the cutter body.
Free floating means unfixed to ANY axis.
Hold it in your hand.

You can't suggest this doesn't work, because it always has.

 

[rwj]

I’ll be curious to see what 21st Century has developed. In the interim, I use the “reverse indicator” method to align the neck mandrel and drive shaft...

 

[Bc'z]

I’ll be curious to see what 21st Century has developed. In the interim, I use the “reverse indicator” method to align the neck mandrel and drive shaft...

Explain please

 

[rwj]

Explain please

Some good videos online... best if you have any millwright/mechanic/machine repair friends that perform shaft alignment demonstrate it...

 

[SGK]

A couple of things to look for. First the expanded case neck should be a snug fit on the mandrel. Lightly lube the inside of the neck. You should be able to turn it with your fingers but feel some resistance. The second, wobble on the rear of the case in the chuck. Any wobble will show up in the neck. (picture is exaggerated). The case head may not be 100% centered in the chuck. There are slight variations in case head diameters.
View attachment 1145758

You're missing the fact that the turning mandrel is meant to float

 

[rwj]

You're missing the fact that the turning mandrel is meant to float

I wonder why none of the neck turning equipment suppliers have yet to offer a mandrel that rotates... like a live center on a lathe?

 

[Straightshooter1]

Straightshooter, stop firing necks, and down sizing necks(especially with a collet), before neck turning.
Take NEW brass, run that Sinclair expander mandrel through it, and neck turn.

Hope you don't mind me being so late to respond. At the time, I didn't have time to respond. So, I happened to get back to this thread and explain why I do what I do.

The reason I fire my NEW brass before turning is that before turning I want the necks of my new brass to be formed to the chamber AND I want the axis of the necks to be in alignment with the axis of the case body, which happens when you fire the cartridge (assuming the whole chamber is in alignment). When those axes are in alignment I get very good consentricity for the full length of the cases.

If I take NEW brass and run an expander mandrel through it, the case neck's interior axis only aligns with the mandrel's axis, which is fine for getting an even neck thickness when turning. Then when the case is fired, the new case shoulder is formed to the somewhat unique chamber and neck and body axes are aligned. Then when I resized the case I've got an issue with material flowing unevenly into the neck from the shoulder as the neck is lengthened where I'll need to trim and turn again to get the concentricity I'm looking for in my cases over time.

I find with my technique, the axes of my case necks and bodies stays aligned when just neck sizing or FL sizing to .0005 or better (measuring the necks inside and outside surface at the same time).

When necks are not turned AND the neck and body axes are out of alignment, the sum of that produces a good sized case concentricity problem. Unturned necks can be a large contributor. If after turning necks to a uniform thickness one is getting poor concentricity (like, .001 or more), it's because the neck and body axes are not in alignment.

I've come to this understanding through extensive experiments and detailed measurements to find what works best and why. Here's a pic of my main measuring instruments I used:

 

[Dusty Stevens]

I wonder why none of the neck turning equipment suppliers have yet to offer a mandrel that rotates... like a live center on a lathe?

When its set up right it will hold and adjust down to .0001. That would be some expensive bearings

 

[rwj]

When its set up right it will hold and adjust down to .0001. That would be some expensive bearings

Been a while since I’ve looked, but my recollection is that small precision bearings aren’t outrageously expensive. A rotating mandrel would eliminate a lot of the heat generated by sliding contact which contributes to process dimensional variation.

 

[T-shooter]

You're missing the fact that the turning mandrel is meant to float

One advantage of hand held turning is both hands can flex and keep the alignment. If the neck position is fixed solid and the other end wobbles, it can't machine straight and will at least have a taper.

 

[MikeMcCasland]

Bumping this thread as I got my 'updated' 21st century powered lathe today. I have some 17-20x fired 308 palma brass I've been playing with, and I'm getting similar results to the OP.

1.) Cleaned
2.) Annealed
3.) FL sized w/o expander in a Whidden FL non-bushing die.
4.) Expanded on a 21st TiN mandrel
5.) Lube Neck w/ hobo lube
6.) Run chuck it up in the lathe and run it on there.

Sized/Expanded the brass measures .015. I'm trying to turn down to .013.

I seem to have a .0005 ES...so my brass will come out .0128 or .0133.

I'm running each piece of brass on there 2x; I'll run it on there slowly to take the majority, then slowly back off....clean the cutter out, and run it back on again.

No heat can be felt, it's got plenty of lube.

I'll probably back the cutter off to just make .001 passes to see if taking less off stabilizes things. I've checked everything recommended earlier in the thread (L-brackets & ensuring it's centered in the collar)

Any ideas?

Nice piece of gear BTW - I'm sure I'm just doing something wrong. Also measurements are relatively repeatable...it's kind of difficult to guarantee you're mic'ing the EXACT same spot every time, but repeatable so far as I can tell.

 

[Straightshooter1]

Bumping this thread as I got my 'updated' 21st century powered lathe today. I have some 17-20x fired 308 palma brass I've been playing with, and I'm getting similar results to the OP.

1.) Cleaned
2.) Annealed
3.) FL sized w/o expander in a Whidden FL non-bushing die.
4.) Expanded on a 21st TiN mandrel
5.) Lube Neck w/ hobo lube
6.) Run chuck it up in the lathe and run it on there.

Sized/Expanded the brass measures .015. I'm trying to turn down to .013.

I seem to have a .0005 ES...so my brass will come out .0128 or .0133.

I'm running each piece of brass on there 2x; I'll run it on there slowly to take the majority, then slowly back off....clean the cutter out, and run it back on again.

No heat can be felt, it's got plenty of lube.

I'll probably back the cutter off to just make .001 passes to see if taking less off stabilizes things. I've checked everything recommended earlier in the thread (L-brackets & ensuring it's centered in the collar)

Any ideas?

Nice piece of gear BTW - I'm sure I'm just doing something wrong. Also measurements are relatively repeatable...it's kind of difficult to guarantee you're mic'ing the EXACT same spot every time, but repeatable so far as I can tell.

Hmmm??? I assume when you "clean" you're getting all the burnt residue off the inside of the neck. My vibrator tumbler doesn't do this, so I wet tumble with SS pins to be sure the inside of the neck is spanking clean. Also, I anneal before cleaning so that any kind of burnt on residue from the annealing is removed. Then, as you do, I FL size just as you've described. I don't use any lube when turning and hardly any heat at all is generated on off the carbide turning mandrel (Sinclair hand turning unit), and I'm turning at about 700 rpm and feeding the neck pretty much as you do to get the necks down from .016 - .015 to .013. I find my ES to run.0002 to .0003. The only other thing that I do different is after turning the neck I give the necks a quick couple turns with 000 Steel Wool for a nice little polish.

 

[MikeMcCasland]

Hmmm??? I assume when you "clean" you're getting all the burnt residue off the inside of the neck. My vibrator tumbler doesn't do this, so I wet tumble with SS pins to be sure the inside of the neck is spanking clean. Also, I anneal before cleaning so that any kind of burnt on residue from the annealing is removed. Then, as you do, I FL size just as you've described. I don't use any lube when turning and hardly any heat at all is generated on off the carbide turning mandrel (Sinclair hand turning unit), and I'm turning at about 700 rpm and feeding the neck pretty much as you do to get the necks down from .016 - .015 to .013. I find my ES to run.0002 to .0003. The only other thing that I do different is after turning the neck I give the necks a quick couple turns with 000 Steel Wool for a nice little polish.

The ID of the necks is as pristine as one can get for 17-20 firings .

I seem to get my most consistent results with a little drop of oil on the neck, and running on/off on/off the cutter. I am however still getting ~.001 thicker pretty consistently towards the donut section of the case.

Given where my reamer has me seating bullets, I don't know that it even matters, but I am curious to see how it performs on new brass.

If anything I'm doing this just to play with a new toy; this brass is pretty well done for, but I do plan to fire it a fireforming gun, then evaluate results next resize/firing cycle.

 

[Petros284]

Bumping this thread as I got my 'updated' 21st century powered lathe today. I have some 17-20x fired 308 palma brass I've been playing with, and I'm getting similar results to the OP.

1.) Cleaned
2.) Annealed
3.) FL sized w/o expander in a Whidden FL non-bushing die.
4.) Expanded on a 21st TiN mandrel
5.) Lube Neck w/ hobo lube
6.) Run chuck it up in the lathe and run it on there.

Sized/Expanded the brass measures .015. I'm trying to turn down to .013.

I seem to have a .0005 ES...so my brass will come out .0128 or .0133.

I'm running each piece of brass on there 2x; I'll run it on there slowly to take the majority, then slowly back off....clean the cutter out, and run it back on again.

No heat can be felt, it's got plenty of lube.

I'll probably back the cutter off to just make .001 passes to see if taking less off stabilizes things. I've checked everything recommended earlier in the thread (L-brackets & ensuring it's centered in the collar)

Any ideas?

Nice piece of gear BTW - I'm sure I'm just doing something wrong. Also measurements are relatively repeatable...it's kind of difficult to guarantee you're mic'ing the EXACT same spot every time, but repeatable so far as I can tell.

Mike, Thanks for your order! Curious as to what kind of ball micrometer you are using (digital or analog) to measure your neck wall thickness? I have also found that carbon can add a few tenths as was mentioned above.

Thanks

Pete Petros 21st Century Shooting

 

[Petros284]

I wonder why none of the neck turning equipment suppliers have yet to offer a mandrel that rotates... like a live center on a lathe?

Trust me this has been looked into. GREAT concept, but costs would be exponentially higher plus any variance in bearings would be magnified to arbor concentricity.

 

[MikeMcCasland]

Mike, Thanks for your order! Curious as to what kind of ball micrometer you are using (digital or analog) to measure your neck wall thickness? I have also found that carbon can add a few tenths as was mentioned above.

Thanks

Pete Petros 21st Century Shooting

You're probably spot on...'China & Amazon's Finest' analog set; they look identical to the ones sold by RCBS/Hornady, I'm guessing same mfg. They zero out correctly ~60% of the time.

Time for a Mitutoyo pair.

 

[Petros284]

You're probably spot on...'China & Amazon's Finest' analog set; they look identical to the ones sold by RCBS/Hornady, I'm guessing same mfg. They zero out correctly ~60% of the time.

Time for a Mitutoyo pair.

At least they are analog What I have learned from John Perkins and his brother Mark here is stay away from digital! I used to use digital all of the time but since I started working here they sit and gather dust!