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Thread: Need advice about reaming a mold

  1. #1
    Boolit Buddy
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    Need advice about reaming a mold

    I have a 6 cavity Lee 95 grain tumble lube aluminum mold. I am considering purchasing a .357 reamer to remove the lube grooves. I do not have a mill so could this be reamed accurately in a drill press, with a cross slide, or is this a fail waiting to happen?

  2. #2
    Boolit Grand Master

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    It can be done in the press pretty much in the same way as the mill. You may need or want to measure the cavity itself before buying the reamer since the "size may also be adjusted for shrinkage and expansion. You might even consider going .001-.002 bigger to get complete clean up of the cavities.

    Heres how to do it in the drill press.

    Mount the mould in a vise on the slide on parallels. A swing in the top surface flat and true this may require some shimming and or tapping.
    Indicate the first cavity in to the spindle and lock down.
    Install reamer in chuck bottomed out in chuck and set the depth close to what you want. Once the cavity is indicated in don't move the table or anything but the spindle. For drill press reaming I usssully turn the spindle by hand with a pin in the chuck. Use plenty of good cutting oil when reaming.
    Indicate and ream each cavity in the above manner

    Most reamers have a 45* cut angle so it will leave a beveled shoulder on the bullet.

    The big thing with the drill press is most stops arnt as accurate or easily set as the mill. The other is in the mill you can indicate each cavity making note of the numbers and then mount reamer and run them thru 123 moving to the numbers.

    For this job I would prefer the mill and a boring head with a sharp boring bar ground to cut a sharp shoulder on the bullet. The lower speeds available on the mill finer stop easier adjustments in X YandZ axis would all make this job easier.

    With the right reamer and a stop collar you could do this with a bench vise and hand reamer.

  3. #3
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    Yea you can and if it fails you are most out only one or two cavities. You need a drill press with minimum runout, most .356" reamers will cut a .359" hole at least. You need a level drill table and a mold that is cut true to the outside dimensions of the mold. Just because the halves have balanced bullets doesn't make them equal distanced from the edges. You need to be able to absolutely true the mold to the press or you will have out of balanced bullets. I would feel OK with reaming gc out but lube grooves involves a long hole. Probably cheaper to buy an NOE mold.
    Last edited by MT Gianni; 11-28-2018 at 09:30 PM.
    [The Montana Gianni] Front sight and squeeze

  4. #4
    Boolit Buddy
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    Quote Originally Posted by MT Gianni View Post
    Probably cheaper to buy an NOE mold.
    That's probably very good advice.

    Thx for the replies guys.

  5. #5
    Boolit Master
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    @country gent:
    Thanks for that description. I had been under the impression that a self centering vise was necessary in either a drill press or a mill. Thanks to your post I see now that it can be set up without it. Not so much for reaming out lube grooves but for making molds from blank blocks.
    I went out and purchased a bunch of stuff necessary to make a self centering vise for making molds and now I don't need them.
    I also believe that the idea of using a collar and reaming it by hand would be perfectly viable for reaming out lube grooves. WAY less risky than using a drill press. You could end up making a mess with a drill press. i just think they spin too fast for this kind of work.
    AKA hans.pcguy

  6. #6
    Boolit Master
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    Quote Originally Posted by Traffer View Post
    i just think they spin too fast for this kind of work.
    They do. In order to not ream an oversized hole, spend as little time as possible inside the piece. Feed it fast, turn it slow.
    Warning: I know Judo. If you force me to prove it I'll shoot you.

  7. #7
    Boolit Grand Master

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    That's why when reaming or tapping in the drill press I use a pin that fits a chuck hole and turn it by hand. In essence when doing this the drill press becomes a fixture to support the reamer square and hold the part in alighnment. A couple strap clamps to hold the vise down will clamp light enough to hold yet allow the vise to be tapped around to indicate it into zero. In this job set up is the big job the actual reaming is secondary.

    The self entering vise is used when cherry cutting a mould with grooves since you cant feed down to cut with out the bands wiping out the grooves. On the smooth sided bullets ( pc coated or paper patched) a form ground reamer can be used effectively. Ideally a form drill would be ground to cut cavity to -.010. This would be done with a heavy flush coolant to remove chips and not heat the blocks, then the reamer set in and under coolant cut / finish the cavity. In this way a mould could be cut fairly quickly and once the tooling is made ( Like the Cherry cutter) the bullet can be replicated over and over. An off the shelf reamer in the right dia could have the form hand ground or form ground ( a tool post grinder in the lathe) and backed off by hand with a fine stone Same with the roughing drill.A harder wheel dressed to form can grind the reamer then the drill. In that order the reamer gets the truest form and the wear is in the rougher that's cut is going to be cleaned up. Now with the cnc machining centers a lot of this is becoming history with the right tooling a pilot hole is drilled and the cavity bored to the program.

  8. #8
    Boolit Master
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    @country gent. Thanks again. Very valuable advise. I have made a couple of crude "core" molds for swaging to the fine finished boolit. It is exciting to me to look forward to a much simpler process of making boolit molds without grooves. I make 22lr "heeled" boolits that still require a smaller dimension at the base though. This still requires a setup that does not plunge the cutter into the mold, hence the apparent need for a self centering vise. But I can envision just setting the cherry at a stationary level and bringing in the halves of the mold onto it without a self centering vise now. I would just have to set it up with it centered to both blocks. If the blocks were carefully drawn into the cherry they would not necessarily need to move synchronously... sorry for diverging from the OP here.
    AKA hans.pcguy

  9. #9
    Boolit Master
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    This is common with Lee molds and as long as both sides warp the same amount, you should be okay.

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