I don't own a case trimmer. I'm thinking use my lathe. Build a "U" shape trough just the size of a cartridge to attach to the aloris tool holder. Set stop on lathe carriage with a cutter in the spindle. Drop cartridge brass in, move carriage to stop, you're done. repeat. I'll need away to stop the brass from spinning that's quick, I'm thinking one of those over center toggle clamps.
Is this a good idea? Got a better one? I'm way to cheap to buy a special machine.
Do you really *need* to trim the cases? I've never trimmed my cases and never had an issue. Granted I haven't reloaded a huge amount, but it seemed to me that case trimming was only for the competitive folks.
Kind of depends on what cartridge you are reloading. My thought would be to make a die that would let any excess length stick out, and then use a file to take off the excess. Depending on the cartridge , it might be easy to make a die that is good enough. For a pistol cartridge just a hole thru a piece of stock that is the right thickness. For rifle cartidges might have to grind a drill to the shoulder angle.
Yes, cases need to be trimmed. On the high-pressure varmint rifle cases sometimes every time, the brass grows that much. Necks may need to be turned, also, for thickness. Failure to trim will run pressures up, with top loads maybe popping primers. With most pistol cases, probably not a whole lot of trimming needed other than an initial one for revolver cases, to get a uniform roll crimp. If you're making brass for oddball calibers from other more readily available calibers, you definitely need a trimmer.
As far as the O.P.'s question, you can get a Lee trimmer set for the cartridge and turn the case lock-base however you want, the cutter has a pilot that sets things to length. That's probably the cheapest method, you can use a power screwdriver, an electric drill or wear your fingers out. A lathe would be a cumbersome method. Forster used to sell a trimmer base to be used with a mill or drill press, just had a toggle clamp for their trimmer collets and a cutter head that took the case pilots. There are two other commonly available trimmers that I consider to be properly engineered, one is the Wilson unit, that uses a ground and hardened sleeve for each caliber, the case head rests against a solid support so it's not only coaxial with the cutter, every case is supported the same way. It's a slow but accurate trimmer. I use a Lyman trimmer, the case holder pulls the case against a solid base, one holder does all types and sizes of cases, nothing extra to buy there. The cutter has a very finely adjustable stop and it doesn't move once locked. You just need a pilot for each bullet size, not each caliber of case. Comes with 9 or so, easy to make new ones when needed on a lathe. Can be powered by hand, a drill or an electric screwdriver, for big spenders, they make a powered version. The other brands use collets to hold the case heads, so no real guarantee that all cases will be the same exact length, the collets move back and forth each time you tighten and release, You also need a number of collets to cover all case heads and will still end up with some oddballs not being trimmable.
Greetings Karl, If I had to trim a bunch of cases I'd do it in the mill. Using a V block and a toggle clamp would probably work well. If you mount the toggle clamp at an angle such that it moves toward the primer end when clamping then the case would be pulled tight against the mill table and the lengths would repeat closely. I have mounted on my Bridgeport a switch that is controled by an adjustable screw that mounts in the quill stop. I use this switch to control a solenoid operated air valve. I have several air clamps that I've cobbled up from air cylinders and the like. When the quill is raised the switch turns on the solenoid which in turn opens the air clamp. If you have enough cases to trim you could save a lot of time. I'll bet a cycle time, part to part, of less than 7 seconds, would be esay to attain. I could post pictures of the switch setup and a clamp or too if anybody is interested. Eric
Hit a local shop and buy a used trimmer. MUCH easier to do AND you get something that you just set up and use. Usually they are also VERY accurate compared to many other methods.
Now if you wanted to use the lathe I guess you could. BUT you don't need any type of channel (which would need to have tapers based one each case type as many have different tapers especially if they are fire formed brass). So you need a case head holder that would lock the head in TIGHT and square to the cutter. Then your cutter should pilot on the case mouth so that it trims nice and square. Then set up the carriage to the case length.
I was never "competitive" but did like to pot 'chucks out to about 350-400 yds ... and that means fairly hot loads , which can cause the brass to flow towards the neck . If your cases are staying uniformly within spec , don't worry about it . If they are starting to crowd the limit , trim 'em all to the short spec . While you're in a machining mood , check neck thickness and turn them all to a uniform thickness .
No, I was actually referring to one of these type:
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But personally I use a Kurt 6in vise that I've fitted up a special pair = of 10in long jaws and two of the enerpac 1in diameter cylinders fitted = to it which works fine with air for light duty holding--I wire the = solenoid valve up use a spare M-function and so the nc program = automatically does the clamping/unclamping for me...
Otherwise, for heavier duty work I'll connect hydraulic up to the same = setup using a haskell m21 pump which gives me 2100psi hydraulic pressure = provided an air supply of 100 psi.
Clamping action is pretty quick because the cylinders have a relatively = short stroke and so the total fluid displacement volume is maybe 1/2 cup = tops.
The enerpac cylinders are actually swing clamps which can be readily = re-configured for straight, left right hand swing and they are = flange-mounted and so they are also easily moved from one fixture to = another.....I actually use them quite a bit here...
HELL OF AN IDEA! I've got four of these. I could set the whole table up and put cases in while the machine runs. I'll grind a 5/16 counter bore down to .300 for the tool. Bet it will do cases faster than I can load them.
Dillon Precision makes (made?) a really nice one that goes in any press. The shell holder goes with the press so you probably already have it. I use it in an RCBS single stage press and it is quick.
10in long jaws and two of the enerpac 1in diameter cylinders fitted to it which works fine with air for light duty holding--I wire the solenoid valve up use a spare M-function and so the nc program automatically does the clamping/unclamping for me...
using a haskell m21 pump which gives me 2100psi hydraulic pressure provided an air supply of 100 psi.
stroke and so the total fluid displacement volume is maybe 1/2 cup tops.
re-configured for straight, left right hand swing and they are flange-mounted and so they are also easily moved from one fixture to another.....I actually use them quite a bit here...
alerts operators that the machining cycle has completed--makes it easier to keep production levels up where you have several machines all making noise at the same time.
I understood what you meant about the vise, I was just proposing that an air collet closer might work well. Setup that noted switch on the mill quill to control an air valve, then just place a shell into the collet against the stop with one hand and pull the mill quill handle down with the other, automatically clamping before the cutter reaches the shell and automatically unclamping when the quill returns up. Seems pretty fast.
I have an air operated 5C closer made by Eagle Rock (I think). It's a good unit made in the USA. I have a piece of 4 inch wide bar stock bolted to the underside of the thing. I clamp the bar stock in the 6 inch vise on the mill so setting it up is real fast. I bored a hole through the bar stock so that a collet stop or long parts can be used with the bar stock in place. Eric
If you reload a lot, and are using high-powered cartridges, the cases stretch, and eventually get so long that the end of the case wedges in the chamber gripping the bullet tighter, and increasing the pressure.
It is a good idea to measure the length, and trim as needed. I'm not sure whether a .357 magnum would grow enough to be a problem, but I do find that the .22 Remington Jet (a bottlenecked case made from the .357 Magnum) do grow enough to need trimming from time to time.
Probably a .38 special would never need trimming, unless you were loading it so hot that it was threatening to blow up the gun every time you fired it
And I would certainly check high power varmint cartridges each re-loading -- if I shot those.
I bought a case trimer decades ago, and it has a set of stepped collets to hold the bases of various cartridges, and the cutter is sort of like a piloted counterbore with a crank. You *do* need a pilot which fits the resized case (trim after resizing) to keep the mouth of the case from walking.
If you can get a big piloted counterbore for the spindle, and some similar kind of collet for the toolpost (or put the collet in the spindle and the counterbore in the toolpost). For this, you either want a depth stop on the collet, or to take a machinable collet and machine a step bottomed fit for the case base. In my case, I would to it the latter way, because I have a lever-style collet drawbar on my lathe, so it would be a lot quicker to change cartridges.
The one which I've had for decades has step collets which position by the front edge against the housing, and the clamp pushes over the taper on the back of the front, so the depth is constant.
I forget the brand, and I'm not going downstairs to check now (it is already after midnight), but for those who might recognize a description, it has a gold anodized aluminum frame, blackened steel parts for the collet holder at one end and the cutter bearing at the other end, a ground and hardened steel shaft which slides in the headstock bearing, and the end of which is the cutter flutes to surround the pilot. A collar slides on the shaft and clamps close to the proper depth, and then a setscrew is adjusted to bear against the outer end of the headstock and locked with a another setscrew to set the length. There is a crank with a nicely bearinged handle to press on while you crank with the left hand. The collet is closed by a T-handle in the right hand. There are three sizes of step collets, which cover all sizes that I have had to fit. I don't know whether there was a forth collet which I've lost or not. :-)
The range of the collets above covers everything that I use. To be honest, I've never checked the fit on a .50 caliber machine gun round. :-) Might have problems with a large shotgun shell too, but they are not trimmed anyway -- or are self trimming over time. :-)
My reloading so far has been 9mm and 7mm Rem Mag. I never suggested not checking the case length though and I do do that on at least a few samples from each batch of brass to reload (all used the same number of times). I haven't found any that have gone out of spec, but I haven't pushed the 7mm brass more than about 4 reloads since I didn't really want to find out the limit of how far they can go before they have issues.
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