Neck turning difficulty

[sbindy]

I ran into those very same issues when I did my cases. I neck turn for everything, so this procedure wasn't new to me, and I had done my 30BR brass so I didn't anticipate having much difficulty. Before I was done, I had to resharpen the tool and polish the mandrel to keep it working right. My mandrel is steel btw. Carbide would have saved me from that grief at least.

For next time, I bought a .220 Russian case holder. Then I'm going to expand the neck, put it in the holder in a lathe, and bore the majority of material away including the donut, then just finish neck turning the O.D. with the regular tool.

It's an extra step, but I did try some cases that were formed using pistol powder and a paper wad, and that seemed to help quite a bit with the donut problem.

Another thought I had was to size the necks up to .25 caliber, then run the case in a 6PPC body die. That would squeeze the neck back down from the outside to .274 and reform the neck/shoulder junction. Then the expander mandrel would only open it back up a couple thousandths. More tools and money spent just to have to turn them all twice. If I were planning on doing this a lot, one of the hydro formers from Whidden would be well worth it.

 

[Hunter]

After expanding, the lower portion of the neck is what used to be the upper shoulder area. Consequently, the I.D. of the lower portion of your newly expanded neck is going to be smaller than the I.D. of the upper part of the neck.

Can you help me understand how the I.D. of any portion of the neck is different than that of another portion, when both were expanded by by the same expander?

 

[Al Nyhus]

Can you help me understand how the I.D. of any portion of the neck is different than that of another portion, when both were expanded by by the same expander?

When you neck up a smaller diameter neck to a larger diameter neck, the bottom portion of the new larger diameter neck is what used to be the shoulder. The shoulder area is considerably thicker than neck thickness and also has quite a bit more 'memory', it wants to go back to what it was before being expanded. This results in the lower portion of the expanded neck being smaller than the upper...the thicker 'used to be shoulder' area doesn't stay expanded out as the neck does.

If you neck turn on a lathe, where the neck is pushed over a mandrel to expand it and the mandrel stays in place during the neck turning operation, you'll get ahead of this issue.

Good shootin' -Al

 

[Al Nyhus]

My setup to ream necks:

Wilson trimmer and neck reamer:

Fit of the Wilson neck reamer:

Additional bushing I make to spread out the bearing surface of the Wilson neck reamer:

You can see how much more support the cutter has with the extra bushing:

Stan Ware made me this reamer handle gizmo years ago....I thank him every time I use it. You can see the reamer is .3070:

Reamer is well supported. The Wilson reamers are nicely profiled to start cleanly and centered in the neck...they were designed to cut brass. The one knock I have on chucking reamers is that some cut too harshly, due to the profile of the cutting flutes and the taper on the end.

Here's the brass removed from the lower necks on fifty 30BR cases I made up not long ago. The cutter was .3060, necks had been expanded over a tapered .2410-.3070 mandrel. You can clearly see the 'lump' at the lower neck that used to be shoulder. The 30BR is an extreme example compared to taking a 220R to .243 but the basics remain the same:



Just how I do it, is all. -Al

 

[OliveOil]

@10ring :

My guess also is that you are facing some "restriction" of the internal diameter at the newly formed neck/shoulder junction. That was very well described by Al just above.

In that very move from 220R to 6PPC, fire forming the 220 first with fast pistol powder and wax plug before neck turning mays show some interest ?

I mean, "blowing out" that new shoulder-neck junction should reduce the amount of material moved by running the 6mm mandrelS and so limit neck base restriction ?




On my own, I was never able to use the Wilson case trimmer fit with the Wilson internal neck reamer and achieve satisfying results. I have never been able to achieve a proper alignment of the new case axis with the reamer axis. It was obvious, measuring the reamed neck thickness, that I was building neck thickness variation.

The issue I was never able to solve is the cone difference in between the new case and the case holder. What I mean is that, firmly pushing the new case into the case holder ALWAYS placed the NEW case axis out of the holder axis. It is small, but one case length further, the reamer was cutting out of axis enough to create an unacceptable neck thickness variation.


Al, I would appreciate much you explain how you handle the new case, the case holder and the neck reamer to have that case concentric with the reamer for this inside reaming operation ?

Or maybe it is a 6BR you fire formed in your chamber at first before starting the neck operations ?? Should you cut the case holder with your own chamber reamer, that would help a lot
in being concentric at neck reaming stage ...



Since that, I went to machines to force the turning mandrel through the "disturbed" area. Machines help a lot. I am also used to push the shoulder to place neck turn stop in shoulder area, once fireformed.

 

[10ring]

@10ring :

My guess also is that you are facing some "restriction" of the internal diameter at the newly formed neck/shoulder junction. That was very well described by Al just above.

In that very move from 220R to 6PPC, fire forming the 220 first with fast pistol powder and wax plug before neck turning mays show some interest ?

I mean, "blowing out" that new shoulder-neck junction should reduce the amount of material moved by running the 6mm mandrelS and so limit neck base restriction ?




On my own, I was never able to use the Wilson case trimmer fit with the Wilson internal neck reamer and achieve satisfying results. I have never been able to achieve a proper alignment of the new case axis with the reamer axis. It was obvious, measuring the reamed neck thickness, that I was building neck thickness variation.

The issue I was never able to solve is the cone difference in between the new case and the case holder. What I mean is that, firmly pushing the new case into the case holder ALWAYS placed the NEW case axis out of the holder axis. It is small, but one case length further, the reamer was cutting out of axis enough to create an unacceptable neck thickness variation.


Al, I would appreciate much you explain how you handle the new case, the case holder and the neck reamer to have that case concentric with the reamer for this inside reaming operation ?

Or maybe it is a 6BR you fire formed in your chamber at first before starting the neck operations ?? Should you cut the case holder with your own chamber reamer, that would help a lot
in being concentric at neck reaming stage ...



Since that, I went to machines to force the turning mandrel through the "disturbed" area. Machines help a lot. I am also used to push the shoulder to place neck turn stop in shoulder area, once fireformed.

Thank you for sharing your findings. I was wondering if the Wilson case trimmer/reamer was THAT good.

What sort of set up did you use to force the arbor past the restriction?

 

[Al Nyhus]

The necks need to be straight relative to the case body before doing any inside neck work, obviously.....

 

[antelopedundee]

What sort of set up did you use to force the arbor past the restriction?

Lube probably. Resizing wax might be a good choice, but it's possible that lube might also prevent the cutter from getting a good bite on the neck surface since one purpose of lubes is to protect metal surfaces from abrasion when contacting each other.

 

[OliveOil]

What sort of set up did you use to force the arbor past the restriction?

You are welcome. I am not that sure of the mean of "arbor", anyway, here is how I proceed with drill press or lathe :


First, I am using some old fashioned dual diameter mandrel on old Sinclair's neck turning tools.



With the drill press :

The drill press offers wayyyyyy enough push force to "get through" .



With the lathe, sorry but I have no pic on hand, sooooo ... when I can have access to a lathe,

unused "rear" mandrel in the lathe chuck.
tool holder on the turret, tool recess facing lathe axis
rotating point (live point??) in place in tailstock
set turret position so that one of the case holder handle will rest in the tool holder all along the needed stroke to push the case all along the mandrel until it reaches the turning stop
run lathe

with fingers of your left hand holding both handles, place the case flash hole on rotating point, gently turn the tailstock wheel until the case mouth gets onto the mandrel, let the case holder handle land on the bottom of tool holder recess , remove your hand, rotate the tailstock wheel to push the case all along the mandrel until the case mouth bumps on the mandrel stop, rotate the tailstock wheel to move the point backward enough, take the case holder handle WITH RIGHT HAND FINGERS and pull it back to extract the case from mandrel while ALWAYS having that case holder handle sliding inside the tool holder until the case is free from mandrel.

Needless to say you don't even feel the neck base "restriction", you just push the excess material out with the mandrel and cut it.

A very interesting part of equipment is the gentle help seating at a little table just next to you. The (precious) help will handle you a ready to turn case in its tightened case holder, with a generous amount of grease inside the neck just at the same time you give him the just turned case in its case holder. The (extremely precious) help allows for HUGE process throughput and HUGE quantities. That's a blessing.

I made some shields to avoid cutting oil projections escaping from the lathe (mandatory). Cutting oil aiming at the neck and cutting bit to cool and lube, 200-230 rpm, allowing for "fast" forward and backward motion of case on mandrel and Go Johnny, Go. I always proceed with 2 cuts, a big raw cut then a small finishing cut. Using the lathe, the raw cut can be quite brutal.

In both case (humor ...), neck thickness variation is less than 0.01 mm (sorry I am metric, it calculates 0.0004"), measured with tube micrometer.

I like to bump shouders 1 to 2/50" at first step and stop cutting the raw pass when the bit comes to contact with that "false" shoulder. Without changing the mandrel setting, I will slightly cut in the false shoulder at finishing cut. That place the neck turning cut end slightly within the shoulder after fire forming (with bullet jammed in the lands). Never had a donut issue since.


Hope I was clear enough and was understandable and of some help.

 

[Kevin Gullette]

Yep, Al.....

The necks need to be straight relative to the case body before doing any inside neck work, obviously.....

I fear that the ol' case "banana" effect discussion may be rearing it's ugly head again.

Anyway.......here's a pic of my old case sorting setup(also used for checking EVERY turned neck......as not all turning setups are created equal). ?

Kevin

 

[10ring]

I fear that the ol' case "banana" effect discussion may be rearing it's ugly head again.

Anyway.......here's a pic of my old case sorting setup(also used for checking EVERY turned neck......as not all turning setups are created equal). ?

Kevin

How do you look for case "banana" effect? What causes such a thing?

 

[GeneT]

How do you look for case "banana" effect? What causes such a thing?

A banana case is caused by the differential stretch when one side of the case has a thinner wall than the other. You can see it has runout on a concentricity gauge - notably the runout will be more pronounced at the case head and shoulder than in the middle.

There's no 100% solution, but you can get rid of most of it with quality brass, a reasonably tight chamber, and not over resizing.

GsT

 

[OliveOil]

The necks need to be straight relative to the case body before doing any inside neck work, obviously.....

Sorry, I apologize, it appears I was not clear at explaining what I mean and my guess about the cause of my issue at the time I was using the Wilson case trimmer with a neck reamer.


I did not point at case neck not being straight relative to the case body, aka "banana case".


What I wished to explain is the following :


Considering that brand new perfect case from an excellent maker, that case body has manufacturing tolerances on both taper/angle and base diameter.

The ""general"" trimmer case holder also has tolerances, so that the smallest holder manufactured WITHIN holder tolerances will accept the biggest WITHIN tolerances NEW case.

That obviously mean that a small but within tolerance case will have ""a lot"" of play in a big, within tolerance, holder.


A new case in chamber case holder goes in some way the same as SAAMI ammo/chamber clearance.


Therefore, when the user places his new ultra straight case in his chamber type case holder, the case axis is mandatory out of the holder axis. The lack of contact area / support in between new case and case holder is easy to blue print. In my case, it was an ellipse.

The reamer will for sure cut on it's own axis, being out of case neck axis, and not being "free enough" to follow the existing hole (inside of the neck), witch is what reamers are usually doing, I mean following and self centering in the existing hole.

I read on the tube mic. that my reaming operation was not doing any good.


That is I think the very point I was never able to solve when using my Wilson CT with the reamer, whether on virgin cases or "donut" used cases, either with the "unfired" and "fired" case holder.

And that's why I quit neck reaming, trashed cases with donut and change the way I neck turn.


One thought that came to my mind while reading Al's above post was to fireform at first with pistol powder and plug, thus making the case body almost even with the chamber wall. Then, using a case holder cut with the same chamber reamer would make fireformed case and reamer quite on same axis.


Hope I explained better this time.

 

[Al Nyhus]

Sorry, I apologize, it appears I was not clear at explaining what I mean and my guess about the cause of my issue at the time I was using the Wilson case trimmer with a neck reamer.


I did not point at case neck not being straight relative to the case body, aka "banana case".

No worries. The case neck not being straight relative to the long axis of the case body and the 'banana case' thing are two seperate situations. For a time, I bought into the 'banana case' theory and all of the supposed issues that went with it. Over time, I came to my own conclusions regarding it and moved forward from there.

One thought that came to my mind while reading Al's above post was to fireform at first with pistol powder and plug, thus making the case body almost even with the chamber wall. Then, using a case holder cut with the same chamber reamer would make fireformed case and reamer quite on same axis.

This is a recent batch of 6BR cases that I f-formed to .30 with pistol powder, tissue paper wadding and a Play Doh plug. There's a lot more to this than meets the eye. Whether mechanically necking up over a mandrel or f-forming this way, I still treat the inner necks.

These cases were good enough to limp me along to a 4th in the 100-200 Grand at this years NBRSA Score Nationals, one of the five members of the Shilen Team Trophy win, an NBRSA 200 yard Agg Score win, an NBRSA 100-200 Grand Agg win and both the Score and Group win at an unregistered 100 yard. event held at my local NBRSA range.

Just my approach to it...doesn't make it right or wrong. For me, the proof is in the pudding, no matter how the pudding is made.

Good shootin' -Al

 

[adamsgt]

Are you using a "matched" expanding mandrel, prior to turning?

The K&M system offers a carbide turning mandrel that also incorporates internal cutting flutes, that eliminate "donuts".

Note.....I inspect each turned case, to insure that my set-up is actually producing necks that are within 0.0001" T.I.R.

Hope this helps.

Kevin

I used that K&M on some PPC brass and had some necks come off during extraction. Kinda disconcerting when it happens.

 

[Kevin Gullette]

I used that K&M on some PPC brass and had some necks come off during extraction. Kinda disconcerting when it happens.

Wow......first I've heard of anyone having that problem.......unless the neck-turner cut too far into the case shoulder.

Did you first run cases through the FL PPC die, before expanding with the K&M expand-iron die?

Kevin

 

[Jim D]

10ring
I had the same problem.

I simply ran the expander mandrel back and forth a few times to correct.
I also lube the mandrel with sizing lube on a tooth brush.

Nothing fancy.

Jim

 

[10ring]

10ring
I had the same problem.

I simply ran the expander mandrel back and forth a few times to correct.
I also lube the mandrel with sizing lube on a tooth brush.

Nothing fancy.

Jim

I'll give that a try. Thanks Jim. -- Todd