Trimmer for copper tubing jacket?

I'm not seeing this talked about, or can't find it. Maybe it's so obvious I am totally missing it. Trying find a way to trim, to exact (as possible) length, copper tubing, to make into a bullet jacket.

I know about using Proxxon or HF mini saw to make a rough cut. But I'm not seeing much about final trimming. Ammosmith on Youtube had a RCBS case trimmer with collet type retension which I guess I can wait around to find it:

https://youtu.be/t8LDGMTA5WE?t=486

Hoping if anyone knows other options out there. Thanks.

A Wilson trimmer could have a holder made to trim it. a spit type so the clamp could be used. set trimmer to zero dust one end clean flip 180* and trim to stop, The rcbs redding style collets wouldn't hold on very much length making holding square more an issue. The ideal set up would be an small lathe with a er collet and arbor with a stop in it. Then face to length. This would make a very accurate set up and allow for deburring in the set up.
I believe the Wilson with a custom holder would be the way to go. the holder would need to be shorter than the jacket so it sticks out both ends. Ten split to allow it to hold the tube jacket. But this would allow the stop to bear on the jacket for location while trimming. This will allow a one set up trimming since you can just dust first end square by eye flip and cut to stop. Locating with a collet accurately can be tricky since dia affects them and how far they sit in the closing tapers.

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Originally Posted by country gent

A Wilson trimmer could have a holder made to trim it. a spit type so the clamp could be used. set trimmer to zero dust one end clean flip 180* and trim to stop, The rcbs redding style collets wouldn't hold on very much length making holding square more an issue. The ideal set up would be an small lathe with a er collet and arbor with a stop in it. Then face to length. This would make a very accurate set up and allow for deburring in the set up. I believe the Wilson with a custom holder would be the way to go. the holder would need to be shorter than the jacket so it sticks out both ends. Ten split to allow it to hold the tube jacket. But this would allow the stop to bear on the jacket for location while trimming. This will allow a one set up trimming since you can just dust first end square by eye flip and cut to stop. Locating with a collet accurately can be tricky since dia affects them and how far they sit in the closing tapers.

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Appreciate all this info. You've given me a lot to work with. Thanks.

It may take some custom work to get these trimmed to as accurate as you want. But it can be done. An old tool maker I shot with made his own dies and a small machine with a double angle collet and stop in it. This little machine turned the jacket at around 3500 rpms and bored the jacket concentric and faced it to length with the pull of lever. With construction grade copper tubing you may want to consider something like this also. A reamer set up for the Wilson trimmer ( or a custom cutter to ream and face ) wouldn't be hard to do. The Wilson trimmer is adaptable to this easily as the only real held dimension is the dia if the case holder it has to be the same as the cutter bushings. A cutter bushing with a .500 hole and a cutter could be made to ream and cut shoulder in one pass.

Another benefit of cleaning up the inside of the jacket is a better bond to the core when swaging it.

you might be better off with some jacket draw dies and sheet copper to get the preciseness you want

I would think that the most reliable and accurate method is to rough trim and then clean up using a collet with stop in a lathe. You can get very repeatable trim lengths with this method. I do some of this type of work and I use a scroll chuck on the cross slide adjusted so it's on center and then chuck up a 1/2" 4 flute end mill. You can lightly deburr before removing from the collet if there is one.

I use a small band saw with a fine tooth blade and the miter slide to make exact repeatable cuts. Wet tumbling them in stainless pins knocks of the burs and sharp edges but if I bump them into the stop properly they are identical to each other. The tumbling really helped me out, it eliminates the copper from sticking on the punch but for a scant few.

I use this little saw from Harbor freight https://www.harborfreight.com/2-in-m...d8288579319ee4
I made a stop jig so I get the same exact length of the cut and nothing really needs to be done. Unless you want to chamfer the inside of the tube.
This little saw turns at 10,000 rpm and makes a very clean cut. I also use this saw for trimming basic cases to the length I need.

I use a trim method similar to Zbench. I bore 5C emergency collets to hold the jacket and put a stop in the collet. I put it in a 5C collet closer on the table of the mill. Chuck a 4 flute carbide end mill in the spindle. Makes quick work of trimming jackets.

Bob

Really appreciate all the help everyone. I think I have access to a mini-lathe, but having issues with room space at the moment. I will entertain the other ideas before trying to squeeze that lathe into my tiny reloading room.

If you go the mini lathe and all it has is the 3 jaw, make up a "spider for the chuck. Use 1/16" thick by 1" cold roll flat stock 2 pieces 1 6" long and one 3" long. With the 6: bend in center to a vee to match chuck jaws. weld the 4: straight off the point out tp form a y and then face to desired thickness. this ten sets in chuck and locates the copper jacket so length can be held easily and consistently. Being held in-between the jaws it cant come out when running.

If you get the mini lathe you will be surprised at the other uses you will find for it.

country gent, that is pretty tricky, a great solution if you don't have a collet and closer system for your lathe. There are no end of uses for a small lathe. I have a 9 x 19 I bought a long time ago and I use it almost daily for something.

I should try to set up trimming on my lathe. I have an old 10 x 24 Logan and a 5C collet chuck that's only 3 years younger than me. I wonder if you can put a stop in a 3C collet. I can use 3C collets with a drawbar right in the spindel and I won't even need a chuck. I don't know if it will be any faster than the mill with having to loosen and tighten the drawbar.

Bob

Bob,

I think it is faster. The drawbar on my collet lathe set up has a wheel on it. I can tighten and untighten it very quickly on the lathe with no tools. It does not have to be bone crushing tight. There is very little resistance when trimming so it just needs to be snug.

Here are a couple pics of my set up. The case I'm trimming is a converted 223 round which is getting trimmed to 300 BO length. I have it set so once I run it through the size die again to expand the mouth it ends up at 1.360". It only varies .001" either way. I've found its the fastest and most accurate way to trim stuff like this.

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