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Thread: Case trimming on the Mill or Drill Press.

  1. #1
    Boolit Master
    W.R.Buchanan's Avatar
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    Case trimming on the Mill or Drill Press.

    I have got the hot tip for you on case trimming. Been meaning to relate this for some time. This method is very accurate and fast.

    some background first;

    On a lathe when you use a 5C type collet your finished part length is at the mercy of the stock's diameter consistancy. On a 5C type collet with a normal pull type of closing mechinism this relationship works out to .003 variation in length for every .001 of diameter change.

    So if you use a collet in your lathe to trim cases to length you can get close if every casehead is the same dia.

    Problem is they're not! and that results in you having to find the largest and smallest case heads and then finding one that is in the middle and then setting up the lathe around the case in the middle and living with the variations. This is also what is wrong with many case trimming lathes, like my older RCBS. It uses a collet that is pulled into a taper to close it and the length varies based on case head diameter. Some newer ones use the rim thickness as the reference which is also not consistant. Also trimming 100 rifle cases on a crank type trim lathe gets old pretty fast.

    Then I remembered I had this device. Have you seen one of these Collet Closers, they are fairly common? Everybody sells them and they are about $50 for a new one and way less for used ones.

    This device operates as a "Dead Length Collet Closer". The collet is threaded into an adjustment ring which is captured in the base of the tool. When you operate the lever an excentric pushes a tapered collar up around the collet to close it. The collet never moves in or out, only the closer ring moves, so case head dia is irrelavant to final trimmed length.

    I simply use a Lee Cutter with an 8-32 SHCS with the head turned to about .302 for a pilot, and then you hand feed down to the quill stop with the mill or drill press turning.

    It is fast and accurate.

    The collet is any used up 5C collet or an Emergency Collet with a .470 counter bore about .06 deep turned into the face.

    Note: Most all collets are made from 12L14, and then case hardened about .01 deep. It is easy to break thru the case hardening as it is not even that hard, maybe low 50's Rc. Note the collet I used has been faced, and was a normal 1/8" collet before I changed it.

    Emergency Collets are made the same way but not heat treated, so they can be easily turnned to what ever diameter or configuration you need to hold a part. I have many that have odd shapes milled into the face for turning of a spud or boring of a hole in a lathe setup which many times is much faster than doing it on a mill. Especially like in a ctr drill, drill, tap scenerio where the tool changes on a mill would eat you up. On a turret lathe it's just a matter of indexing the turret for the next tool a few times, and then you're back at the start for the next part.

    Note: There are a zillion cartridges that use the .30-06 case head size so one collet can do alot of different cases. Obviously there are other common case head sizes so you only need a few collets to devote to this project. I have 2 so far.

    Hope some of you machinist types can use this info, but the beauty of this is, you don't really need to be that much of a machinist. You could have a shop or buddy make the collets for you and just use a drill press and this type of fixture. The key is the "Dead Length Collet Closer".

    Randy.
    Last edited by W.R.Buchanan; 10-18-2011 at 06:42 PM.
    "It's not how well you do what you know how to do,,,It's how well you do what you DON'T know how to do!"

  2. #2
    Boolit Master
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    I tried the Forster case holding collet on my drill press and the setup was not very repeatable.
    On a much better drill press, late or mill I am sure it would be great, but not on my cheap drill press.

  3. #3
    Boolit Master

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    The Forster is reliably repeatable in its original tool base.
    Many re loaders complain about variation in cuts however. The reason is because they do NOT clean the faces used as measurement control.
    Lube, lube, lube! Go crazy with the lube and screw up your measurements.
    Lube layers cause measurable errors.
    The measurement faces do not rub, don't need lube. They contact dead on, f/f.
    Keep them clean and your measurements will NOT vary after set.

    Hint, FWIW, When making the final adjustment use 2 wrenches. One for the adjusting screw the other for the lock screw If you don't hold the adjustment screw it will turn/change when locking.
    Pepe Ray
    The way is ONLY through HIM.

  4. #4
    Boolit Master
    W.R.Buchanan's Avatar
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    The whole Idea here is the dead length collet closer. It is an inexpensive method of locating the cases under a cutter, that is quick to change, thus increasing your productivity. Trimming 500 rifle cases in this fixture would be far more enjoyable than doing it any other way readily available to handloaders. In fact every other way I have down right sucks after about 20 cases.

    I have never seen a Forester base up close, if it uses a collet that is drawn into a taper then it is at the mercy of the case's rim diameter and if this varies then OAL will vary.

    IF it uses a collet that pushes the case head down on an independent stop then it will repeat regardless of case rim diameter also.

    As far as your cheap drill press is concerned, If the quill stop works and actually stops the quill, it should repeat. Doesn't matter how expensive it is. It is nothing more that a threaded rod with a nut on it, and if the nut is fixed in place then the quill will repeat.

    The issue is always getting the case into the same position. The Lee trim system works very well in doing this, but is a little slow for long runs. It uses a dead length method of locating the case and then the probe defines the over all length. I have many of them, and use them sometimes.

    A long as you can locate the case base the same way every time under a quill that drops to the same position everytime then your cases will all be the same length.

    Randy
    Last edited by W.R.Buchanan; 08-09-2011 at 09:51 PM.
    "It's not how well you do what you know how to do,,,It's how well you do what you DON'T know how to do!"

  5. #5
    Boolit Master


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    One method I've been using for many years is the Lyman Drill Press Trim Tool. The base is mounted to a 1/4" piece of steel plate that is clamped to my drill press table. The quill stop determines the depth of the cut and since the base of the shell holder is stationary, it's very repeatable. When the outside collet is turned in, all it does is move the two jaws straight in to grasp the extractor groove of the shell to be trimmed. The spring loaded ball indexes into the empty primer pocket and ensures proper alignment.

    I don't think they make the tool anymore, but I just picked up another base in new condition from one of the auction sites for very little.

    Hope this helps.

    Fred

  6. #6
    Boolit Master


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    The forrester trimmer base made for useing a mill or a good quality drill press works excellent !
    a friend just bought one and used a mill, we processed 2,000 mil 308 and 1,500 mil 223 with excellent results .

  7. #7
    Boolit Master
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    Just buy a Giruad and be done with it. I trim all my cases to within .002.

  8. #8
    Boolit Master
    Ed in North Texas's Avatar
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    Quote Originally Posted by ReloaderFred View Post
    One method I've been using for many years is the Lyman Drill Press Trim Tool. The base is mounted to a 1/4" piece of steel plate that is clamped to my drill press table. The quill stop determines the depth of the cut and since the base of the shell holder is stationary, it's very repeatable. When the outside collet is turned in, all it does is move the two jaws straight in to grasp the extractor groove of the shell to be trimmed. The spring loaded ball indexes into the empty primer pocket and ensures proper alignment.

    I don't think they make the tool anymore, but I just picked up another base in new condition from one of the auction sites for very little.

    Hope this helps.

    Fred
    I would add that the component which may cause problems is the drill press. After my first efforts with my Lyman, I'm not using it again until I buy a better drill press than the el Cheapo I currently have.

  9. #9
    Boolit Master
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    Ed in TX: if the quill stop on your drill press is tight IE the stud or clamp is not loose on the quill, and the lock nuts on the stud are tight, it will work just fine.

    I've had several El Cheapo drill presses in my shop and use them for operations like chamfering a part after I do something in the mill. I have never had a problem with them not repeating as long as the quill stop stud is tight and doesn't move around, and if the lock nuts are tight as well. It simply must do the same thing every time when these two things are solid. If it doesn't have a solid stop then make it so it does. Much easier than buying another chinese POS. Also watch garage sales for nice old Craftsman Drill presses. I have one that is older than me, and is still perfect. Paid $25 for it.

    I've seen guys destroy one of the little chinese band saws just because the blade pops off. Simply taking the wheels putting them in a lathe and recutting the surfaces so they are round and strait fixes this poblem. I have had mine for nearly 30 years I paid $125 new for it and it has paid fo itself 100 times easily. I use it on nearly every job I do to cut a peice of stock.

    Sometimes a little TLC is all the tool needs. I am currently rebuilding an 18" Crescent Wrench a guy gave me. It was rusted solid but I have broken it loose and now am trying to get it apart. As soon as I get it apart I can blast everything clean and detail all the snags out of it and I'll have a new tool that if I had bought it was close to $200 now. I'll have an hour in it when done, and even at my high prices that's still a good deal.

    Randy
    "It's not how well you do what you know how to do,,,It's how well you do what you DON'T know how to do!"

  10. #10
    Boolit Master
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    Quote Originally Posted by Ed in North Texas View Post
    I would add that the component which may cause problems is the drill press. After my first efforts with my Lyman, I'm not using it again until I buy a better drill press than the el Cheapo I currently have.
    I would agree as my drill press is a cheapo. I have a couple of Forster case trimmers that are very accurate which is one of the reasons why I decide to try the base on my drill press. I believe it would work great on a milling machine or a top quality drill press, but it is certainly not repeatable on MY drill press.

  11. #11
    Boolit Master flashhole's Avatar
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    I just use a Lee 3-Jaw chuck in my drill press with the Lee Case Length Gage. Very inexpensive and exactly repeatable every time. Of course you need a drill press or cordless drill to use with it.
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