Lathe method of cutting cases for jackets

[PWS]

Here's a simple way of cutting cases to length - provided you have a lathe! I couldn't live without one now, even a super cheap bench top model.

It works for major length reductions for reloading too.

There's a Morse taper socket for the spindle bore that holds a stop rod. Pretty simple to center bore the taper 3/8" or 1/4" and install a random length rod long enough (or skinny enough) that it doesn't interfere with the jaws. Three jaw chuck works fine, a little wobble doesn't hurt.

The cutter has a knife edge made from heat treated O1 steel. It has a slight tip backwards from 100% vertical and is beveled flush with the case body and angled in from the mouth side. This leaves the save end square and the discard end a little collapsed. A minimal touch of beeswax ever other case or so really helps with the cut. Give it a quick chamfer before pulling from the chuck and done!

Lock the carriage close to the length you want and use the compound to fine tune. This method gets me within +/-.002 on lengths and usually better. Good enough that I don't do any further length modifications to the jackets.

[R.Ph. 380]

Looks like it'll do the job, I just use the Lyman universal brass trimmer with power attachment. My 18v Ryobi drill takes about .45 sec to trim each 40 S&W to 0.738 (which is my ideal) to make 45acp.

[jdfoxinc]

To save having to open AND close the Chuck for each case use a lee case holder in the chuck. A quick twist of the lock ring and change cases.

[DukeInFlorida]

Like driving a Mack truck to the grocery store for food?
Yes, it can be done, but there are simpler and easier ways.

[PWS]

Perhaps there are "simpler and easier" ways but I already have a small bench lathe and this method works great for me.

Never drove a Mack so I'm not going to jump to conclusions on how that would work for errands...

[marvelshooter]

I like it. It's how I cut my .223 brass to make blackout cases.

[Zbench]

Using a 3 jaw chuck is a good start, but the ultimate is to get a set of 5C collets and a collet closer. I bought mine from the Little Machine Shop. There is an adapter that fits in the headstock Morse Taper that accepts the collet. There is a draw bar with closing wheel that fits through the spindle bore. That coupled with a stop inside the collet is quick and easy. I have a 3 jaw jabobs chuck I mount on the cross slide with an end mill. Just put a stop on the bed and use the cross slide for fine adjustment.

You just chuck the part, fire up the lathe and use the carriage wheel to advance the end mill and trim it fast and effortless. I use it to trim black out brass and even bullet jackets if I don't want to set up the pinch die. If you get good at it you can grab the wheel after you turn off the power to the lathe to open the collet. I can do 3-4 parts a minute or even more depending on how much you are hogging off. Accuracy is phenominal.

Finally, if you can't find a collet to work, they sell "emergency collets" which you can bore to whatever diameter you need.

[M-Tecs]

The OP pics indicate he is cutting large amounts off for jackets.

I have soft jaws for my chuck that I have turned the matching taper and a stop into the jaws.

For 300 BO I have a Dillon 1500 but that requires a trim die and some conversation no dies are available.

Normal trimming jobs I have other methods that are faster but the lathe works great for taking full length cases down for jackets or conversions.

[footpetaljones]

Even better than using 5C collets would be to use 3MT collets directly in the spindle, to avoid any runout in the adapter.

[Zbench]

Not sure runout matters when you are trimming from the end

[smokeywolf]

I have a bushing about 1.70 long, that I made from a short length of 1" PVC. Bored the I.D. to the size and taper of a 45-70 case. With a collet stop in a 1" 5C collet, I insert a 45-70 case into the bushing, insert case & bushing into the collet with case head against collet stop. When I snap the collet draw bar back it squeezes the PVC bushing just enough to grip the brass without resizing it. Carriage locked off, I use a 1/16 parting tool to take the needed amount of brass off to make 45-70 cases into 45-60 cases. Including deburr and without any rush, I can knock off about 2 per minute.

[Zbench]

Smokey,

You method is similar to mine, I like the approach to overcome the rimmed case. If you have an arbor adapter for your quick change tool post, you might try the end mill. It's crazy fast and doesn't leave a burr if you start with a sharp cutter.

[PWS]

Great ideas guys! The slow spot in what I'm doing is definitely at the chuck. I hold the key ready in my left hand but it still requires opening and closing the chuck. Some kind of quick grab collet would, no doubt, be better. I batched about 2000 .223's in November so that'll last a while.

Never thought of using an end mill from the case mouth end. Tried a parting tool into the side but it would grab on the thin wall, especially since the cases aren't concentric and/or get a little distorted by the chuck jaws. The parting tool would pop through at one point and snag. The vertical blade works but it does leave a burr after slicing that needs to be addressed. An end mill is certainly worth a try and would save the deburring step.

As an aside, I am scheming about a round over die to pre-round the waste end and maybe turn those into jackets too. As a prototype, I made a concave hemispherical punch to replace the decapping pin in a .357Mag carbide die and it worked to roll in the case mouth some. Trouble, however, is that the cases would get about half closed before the shoulders would buckle enough to hang up on the carbide ring on the way out. Gonna try a similar punch in a FL .223 die to see if full support of the case wall from the outside will be enough to roll the mouth in and not buckle the body. If it works, it will be possible to utilize both ends of the parted case.

[R.Ph. 380]

Great ideas guys! The slow spot in what I'm doing is definitely at the chuck. I hold the key ready in my left hand but it still requires opening and closing the chuck. Some kind of quick grab collet would, no doubt, be better. I batched about 2000 .223's in November so that'll last a while.

Never thought of using an end mill from the case mouth end. Tried a parting tool into the side but it would grab on the thin wall, especially since the cases aren't concentric and/or get a little distorted by the chuck jaws. The parting tool would pop through at one point and snag. The vertical blade works but it does leave a burr after slicing that needs to be addressed. An end mill is certainly worth a try and would save the deburring step.

As an aside, I am scheming about a round over die to pre-round the waste end and maybe turn those into jackets too. As a prototype, I made a concave hemispherical punch to replace the decapping pin in a .357Mag carbide die and it worked to roll in the case mouth some. Trouble, however, is that the cases would get about half closed before the shoulders would buckle enough to hang up on the carbide ring on the way out. Gonna try a similar punch in a FL .223 die to see if full support of the case wall from the outside will be enough to roll the mouth in and not buckle the body. If it works, it will be possible to utilize both ends of the parted case.

Bet you need to anneal before rolling in the case mouth

[midnight]

I use the 5C collet method with nylon emergency collets and an adjustable collet stop except I use it with a collet closer on the milling machine. Mostly used for jacket trimming since they have no rim. An end mill in the spindle does the cutting. Never did like pinch trim dies. They don't completely cut the jacket and you and you have to pick off the scrap.

Bob