Case trimming in the lathe

[EDG]

I will reload about anything including turning rims, cutting extractor grooves and making the reloading tools.
Because of the versatility of a lathe you can do things such as making cartridge cases from bar stock, reloading dies or reboring bullet molds.
The variety of that other stuff is handloading.

Well, I personally do NOT reload every case on the planet. Only normal standard calibers. Not that other stuff some mention on here.

If one loads those cals, then have at it with a lathe device. I will stick with my fast & efficient Lee product. And spend my lathe & mill time making scientific and antique instrument and clock reproductions & repairs.

banger

[Rick O'Shay]

This is what I did with my RCBS Trim Pro. Made life a little easier.

[Whiterabbit]

That made me head to the lathe to try.
THANKS

My best advice for perils and pitfalls:

Test cases for uniformity of length. Not all datum points are acceptable. For example, my first test was to punch the primers out of the brass, run the guide pin WAY long, (loctite in place), and put the shoulder of the pin on the inside of the case, letting the primer pin just spin freely out the back. Buzzed a few cases in there b hand and measured them. Not even close to accurate. you can get within a couple thou easy using different datum points. Or of course using the lee case chuck so the pin has a positive stop at the base of the cartridge.

[leadman]

I bought the new Lee trimmer and the power adapter. I use a Black & Decker rechargeable screwdriver. I do get some chips caught behine the blades on occasion and it changes the angles of the trimmer. I still like the older Lee trimmer with the case holder in an 18v cordless drill so it stays upright by itself. I clamp a small vise-grip on the cutter to make it easy to hold. I can either chamfer the case in the drill or use my RCBS Trim-mate.
I saw a gun smith use round white plastic, think it was Delrin, that he bored thru for the case and cut off at a certain length. He split one side of the plastic so when it was clamped in the 3 jaw chuck it held the case firmly. He use this setup only for some wildcat cartridges he would chamber customers guns for.

[rondog]

You should be able to find a good lathe on Craig's list in a big area like Denver. I would be lost without my 5 metal lathes, 3 wood lathes, and 2 milling machines! If I did not have any, I would go without food to afford one.

No $$$$ to buy one, no place to put one. Too poor, garage too small and packed. Recently got a better job, maybe we can move someday. Wife is all for it already.

5 metal lathes, 3 wood lathes, and 2 milling machines? You suck! Suppose there's 5 or 6 welders there too.....

[rbuck351]

Whiterabbit
That is similar to what i have been doing except I was using the Lee case holder and stock length pin gage. Your method is now my new way. I don't think there is any way that could be faster unless you built a machine you could dump the brass in and push a start button. Pick up a piece of brass, shove it on the cutter/length gage and drop. With a bit of practice I think you could get it down to 2 to 3 seconds per case. Even at 5 seconds per case it's 720 per hour without you turning anything. Thanks for that tip. Get enough people working on something and someone will come up a really good solution. This could be done on a drill press as well, just verticel instead of horizontal.

[Whiterabbit]

Well that is a change. I was crucified on a more snobby bulletin board for suggesting this method. Thank you for the affirmation.

[rbuck351]

Some folks are afraid to admit that someone else may actually have a better idea.

[Huvius]

There was some talk of doing 577-450 on a lathe and it would be just the same method as how I trim my 577-500 on the lathe.
No way would I try to clamp the brass in the collet!
Simply make a mandrel which fits well into the neck which is held in the chuck. As long as the internal depth is consistent with your brass, and you have a live center to hold in the primer pocket, it is a snap!

I just posted this on Nitro Express so some of you may have seen this already.

I set up my mandrel (.5" scrap stainless steel) and the cutter with a factory formed Bertram 577/500 No.2 case and then slipped a case formed from the basic 577/500 brass and found that there was quite a difference.
Anyway, once I adjusted the cutter to work with the new cases, I found that these are in fact very consistent internally and began the trim. I measured each piece and there may be .001" off here or there but not enough to worry me.
Also, I have a live center for my tail stock which allows me to hold center while firmly pressing the case onto the mandrel. That kept the case from spinning on the mandrel and after a few cases, I got a feel for how much pressure I was applying with the tail stock and tried to stay consistent with that.


Here are some pictures:


This method works great right from full forming and FLS in the reloading die.
The SS mandrel.
I cut a little relief into it with the same cutter I am using for the brass. The cutter is a little angled for two reasons. First, as the cutter advances through the neck wall, the remnant is pushed down the mandrel away from the case mouth. This makes it easy to see when the parting is complete.
The second reason is because I once dropped my deburring tool and one of the legs broke off at the tip... so now it will not chamfer a case as big as .500! I figure angling the cutter will give me a bit of a chamfer on the case while cutting it. Also, I hold a bit of steel wool at the cut before removing the case from the mandrel to really smooth it out.





sliding onto the mandrel toward the relief groove.
That's a little ring of brass in the groove from the previous case.



Fully seated.





This is the live center on the tailstock holding the case in place.





Cutting.





And the finished length.




Another benefit to doing cases on the lathe is that the rims can be trimmed back if needed while it is on the lathe although a multi-tool holder would be best for that.

[jmorris]

I have done it on a CNC mill before.



A Dillon trimmer is a LOT faster (over 1000/hr) is pretty easy and costs a lot less.

[EDG]

This can be fast right up to the instant you stuff your hand into the spinning 3 jaw chuck.
You would be safer using a collet chuck or an electric drill.
I just think pushing with any force toward the chuck is eventually going to get you hurt. That is based on about 10,000 to 12,000 hrs running an engine lathe and a wide variety of turret lathes.

Howdy YV,

I do 400 cases in 15 minutes on a lathe (personal best). That's trim, deburr, and chamfer.

Here's the caveat: I'm not making big cuts. No .1" reductions. Just normal trimming-once-fired-brass kind of trimming. Not "forming". That said, 400 in 15 min is not hard with my setup.

Here's how I do it:

#1: use LEE case trimmer plus piloted bits.
#2: set your cut length by trimming the pin if needed. For max speed you need to use a primer as the datum. I will be intentionally vague there. But you can use the standard twist chuck for the cases and probably get 150-250 cases done in 20 minutes or so.
#3: you put the CUTTER in your 3 jaw scroll chuck.
#4: you set up 3 bins in front of the lathe. One for untrimmed, one for trimmed, and one for cases you tried to trim but no trimming happened (aka no need to chamfer and deburr this bin)

The caseholder you will have to screw into a ball (like a muzzleloader shortstarter) or similar. If you don't need the lee chuck for datum, then you can just hold onto the case itself, like using a WFT chucked into the lathe.

you apply the case to the cutter by hand. While the right hand pushes the case into the cutter, the left hand grabs another untrimmed case. When right hand falls to drop the case into the trimmed bin, left hand meets the right for the case changeover.

Max time is spent applying brass to the cutter. It's very, very fast when setup right.

When finished, take the cutter out and put the debur in the lathe chuck and repeat the process, holding the brass by hand. 2x for debur and chamfer. Fast.

[Whiterabbit]

This can be fast right up to the instant you stuff your hand into the spinning 3 jaw chuck.
You would be safer using a collet chuck or an electric drill.
I just think pushing with any force toward the chuck is eventually going to get you hurt. That is based on about 10,000 to 12,000 hrs running an engine lathe and a wide variety of turret lathes.

You are absolutely right EDG. Every activity, whether it is case trimming, reloading, firing a gun, riding a bicycle, has some associated risk. To engage in any of these behaviors and much more without understanding the risk involved can increase the chances of injury up to and including death. If the risk cannot be mitigated sufficient for the comfort of the person engaged in that task, it's better that they don't engage in the task. Knitting is always available as a low injury risk activity.

[EDG]

You don't really have to avoid the task just use a better or safer process. The problem with a lathe is if you have never had or seen a significant wreck on one you may not anticipate the danger. Many workers do not anticipate the increased chance of injury that goes with repetitive operations that may last for hours. You can easily do 50 or 100 or maybe 200 cases without a problem but somewhere between 200 and 10,000 cases you may goof.
I am sure there are people with repetitive motion injuries from knitting.

You are absolutely right EDG. Every activity, whether it is case trimming, reloading, firing a gun, riding a bicycle, has some associated risk. To engage in any of these behaviors and much more without understanding the risk involved can increase the chances of injury up to and including death. If the risk cannot be mitigated sufficient for the comfort of the person engaged in that task, it's better that they don't engage in the task. Knitting is always available as a low injury risk activity.

[Safeshot]

I still like to use the Lee Case Trimmer in a Drill Press. Set the drill press spindle stop so that the spindle stops just as the pin touches the table. This prevents extra pressure being applied to the pin and prevents excessive wear or damage to the pin. (The trimmer stud and pin control the trim length and it is very accurate.) Just hold the case in position (a nitrile rubber glove on the hand holding the case in position makes it a lot easier) or use pliers with leather padded jaws to hold the case in position, if desired. This approach is so fast that most people that have never tried it will not believe how fast it really is. Just my opinion.

[Huvius]

I guess the point is, that if you are needing to trim a lot of brass, there are much better methods than using a lathe.
However, if you are working big cases and are needing to trim less than 100pcs or so, the lathe can be a very good way to do that.
I am trimming these particular cases because I started with 577 basic brass which means that I HAD to trim them. I doubt that I will need to trim them again ever again being big bore black powder rounds. That is my hope anyway.

[GONRA]

GONRA uses my boyhood 12" (between centers) Craftsman lathe (screw cutting, only $50 in 1950's)
with a modern imported (pricy) 1/2-20 threaded 3 jaw universal lathe chuck and
home made tailstock support / usual el cheapo Harbor Freight carbide insert cutter, for .50 BMG brass trimming.
(Case head backs, stops inside this small chuck for length reference.)
Verked great for me - 1200 rd. Scrap Dealer case prep a couple years ago.
(For a great hobby project, use yer BIG LATHE to make proper feed screws / 1 mil dials for this little lathe. Its worth it!)

[fjruple]

Due to bad old hands I have a cheap Harbor Freight lathe which I use to trim cases for 35 Winchester Self Loading Cartridge, make .455 Webley MKII from .45 Schofield, .45 Cowboy from .45 Colt and current rimming 5.56mm to 5.45mmx39 Russian. I use a RCBS Trim Pro Cutter and a Universal Holding fixture. I have made mandrils, made firing pins and turned pistol barrels on the lathe. attached is a picture of my lathe setup for trimming 5.56mm brass to 5.45mmx39.

--fjruple

[shortfal]

For shortening .308 cases to convert to 8 Kurz I turned a piece of round stock with a pocket about .063 deep to accept the case head and a shaft just under boolit dia. that goes thru the case with a tit to go in the flash hole. it extends about an inch out the mouth to a diameter that is large enough OD to have a center drill cut a recess in it to accept a live center.
The shaft traps the case between it and the pocket in the piece of round stock in the chuck. I part off with a sharp piece of cutter bit about .050 wide. With care I can change cases without stopping the lathe.

Pete in St. Louis

[Nueces]

Nicely done, shortfal.

[shortfal]

Nicely done, shortfal.

Thanks, Works really fast and dead on every time for whatever length you want. It's the deburring, necking, inside reaming, final trim and another deburring that eats up the time.
Pete