Help! inside neck scratches

Vern

Vern

Morethan1waytoskinacat
I just bought a new K&M turner.
It came with the doughnut cutter.
It is leaving some minor scratching on the inside of the case necks.
I think it may be caused by my case holder in the drill. It seems to hold the case a little off center which creates a small amount of wobble.
It seems to happen on the exit off of the turning mandrel.
They don't seem to be deep but just enough that when I slide a dental pick up and down on some of them I can feel minor scratches.

I have only done the 1st turning on them.
Is this a serious problem or can I just take some 600 or 1000 grit paper and polish it out?
I will be getting a new case holder this week.

Do I need to resize and re-expand after polishing before I do the second turning?
 
Vern, I agree with Glenn:

What I have done(with the disclaimer that I am no expert at this) is after the first firing, the donut is obviously on the inside. I re expand with my expander mandrel that matches my turning tool. With the donut now on the outside, I re turn the case neck carefully at the same setting as my original turn(if the case neck remains same thickness, which mine do). This allows removal of the donut on the outside, taking care not to go too far into the shoulder. You can check before and after with pin gauges(a whole set of 50 or more gauges cost me about 50-60 bucks thru MSC). Appropriate sized neck bushings can also be used to check results down the case neck, remembering that the stamped dimensions are not as stated to allow for spring back.
 
Vern, for what it's worth, I recall from somewhere that you often get wobble in the case when using a drill and case holder. What I was led to believe is to not try to overcome the wobble, but go with the flow, so to speak. Also, do not clamp the drill in vise in attempt to overcome the wooble. This applies only to case turning with a drill and not with lathes or other means of turning necks.
 
My problem started with a really bad batch of 220 Russian brass that after two firings developed serious doughnuts. So, I bought a K&M doughnut cutter and had a go at removing 300 doughnuts.

After struggling with 50 cases and a pile of brass shavings thrown up by a wobbly drill action, I realized using a K&M doughnut cutter and a drill was a bad idea, as I not only removed the doughnut but a considerable amount of inside neck brass.

I asked an engineer colleague to resolve the issue without removing brass from the inside of the case neck. He started by turning and epoxy gluing a brass 1'" x10mm diameter brass stub inside a 2MT keyless chuck. You could then insert the 220 Russian case and close the chuck, holding it square. Fit the K&M doughnut cutter in the lathe head stock (we used a small bench top lathe), run the case manually over the cutter until you are just about over the doughnut. Switch the lathe on at this point and drive the cutter over the doughnut, cutting it. Stop the lathe, and manually back it off over the case. You could also use a vertical drill press to achieve the same result. You will find the K&M cutter works a treat.
 
Hey Glen how is it going?
Long time no see.

I didnt realize they made a regular mandrel Ill get one this week along with a new case holder.
I have had this one for about8-9 years but never worried to much about it until now.

I dont fight the wobble when using a drill but it is the case holder causing the wobble because I can not push the case into the holder quite all the way and it is pretty straigth then.

Thanks for all the info guys.

What about the brass that is lightly scratched. Right now they are only turned to 0102?
Use a little wet dry paper resize and re-expand?
 
Thanks Glen.
I downloaded that the other day and I found that it does take 2 turnings to get it good but a 3rd turning seems to make it right on the money and very even.
So far no one has asked me to turn brass for them. I have thought about it but only if I got a bench top lathe to do it with.
HOWEVER I would turn some for you at no charge, that is if you are serious.
Let me know.
 
Now Glenn, If you want to borrow my sinclair turner just let me know... Makes life real easy with that and the hart turner....

Just cleaned up my brass the other day and took it down a little more and also turned some new....
 
Well at least you can load that spud with butter, sour cream and all that good stuff and get some good calories out of it...Ha Ha Ha....

If it decides to warm up lets hit the range !!
 
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