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Thread: Has anyone ever made a mold with drill bits?

  1. #1
    Boolit Buddy Kegcaissy's Avatar
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    Has anyone ever made a mold with drill bits?

    Hi!

    Like title says, has anyone here ever attempted to make a mold using jobber drill bits? I'm planning to do just that on a lee mold by using the undersized cavities to align my two holes (i plan to use a 223 lee mold). I have access to a good press drill and i will use brand new drill bits. A dial will be use as a depth gage. The boolits from this mold will be powdercoated or lubed with alox if it's possible.
    We really need a Ar-15 subforum!

  2. #2
    Boolit Grand Master

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    Drill bits do not drill accurately sized holes... usually anyway. Typical twist drills tend to drill oversize by a couple thou or so. Drill bits also don't tend to leave a good finish. Better to drill undersize then ream to final size.

    Even better to make a D-bit the shape you want your boolit then drill undersize and final ream with the D-bit.

    What size are you after? Getting drill bits and/or reamers in the exact size you need may be an issue too. Letter or number drill bits and reamers may do it.

    Lee moulds are inexpensive so no big financial cost if it doesn't work but I suspect a drill press won't have the accuracy required so cavities will not be well centered or perpendicular to the mould top. A milling machine or lathe is a better bet for accuracy. I drill then bore to size on my lathe or make a D-bit and ream to size on the lathe. Mind you I don't make split moulds either. Mine are like the old Ideal cylindrical moulds and they make a perfect smooth boolit good for paper patching, powder coating (though I don't powder coat) or knurling then tumble lubing.

    I have made moulds for bore nose riders with groove diameter base and tumble lubed those successfully even smooth. In fact so far the most accurate boolit I've shot from my Lee Enfield .303 British is a smooth boolit of that design. I get better accuracy from it than my NOE 316299 with gas checks. So, yes, tumble lubing smooth boolits can work. Powder coating should work fine too.

    Longbow

  3. #3
    Boolit Grand Master

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    The way to do this is to use the drills to get close. then ream and lap to final size and finish.
    Set up blocks in drill press vise lock down lightly and indicate in
    lock down tight and check to insure they haven't moved
    Drill undersized to rough in
    drill .015 undersize
    ream under .003-.005
    Finish lap to size and finish
    With a little work and patience you can form grind the nose on the drill to cut just what you want. This can get involved and does require some hand work with stones.
    Several things to take into account when doing this are Spindle play and run out, chuck run out and squareness, machines squareness. Sometimes tables can be adjusted in one direction but usually requires shimming the vise to square with the spindle.

  4. #4
    DOR RED BEAR's Avatar
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    I have to agree with drilling small and reaming. You can get a drill to drill very close to size if sharpened correctly. I have seen brand new drill not sharpened correctly. Less likely to be incorrect with quality drills.

  5. #5
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    I've made a couple of them but usually for non critical things like J-word cores.
    Old enough to know better, young enough to do it anyway!

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  6. #6
    Boolit Buddy Kegcaissy's Avatar
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    I'm looking to make a flat nosed bullet for a 32 SPL rifle, 0.315''body X 0.325'' bands. It seems to be possible with standard sizes reamers. I'm still willing to try first with modified drill bits.
    We really need a Ar-15 subforum!

  7. #7
    Boolit Grand Master

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    As I said it can be done. We made some molds for test slugs using drills and reamers. (But we also had a cutter grinder handy to sharpen the drills) These were a 3" long slug 1/2" on each end with 1/8,1/4,3/8, and 1/2 sections in the center.

    Drill close to depth but stay .010-.015 shallow of depth with standard drill and or reamers.
    if you want a special nose on it make a template like a square with the nose form on the short side. Mark center point of nose to web of drill before starting
    Grind nose to this pattern, paying attention to the drills center web in relation to the mark. This keeps the form centered and cutting even.
    Back off the drill ( relieve to cutting edge) by hand with a stone, Ink on the face helps see the edge of the drill.
    Cut the nose portion to depth

    Some tips.
    Have a piece of aluminum scrap to check drills with cut to size and finish. Sometimes a little work with a fine stone makes a big difference in size and finish. Check new and after grinding the nose form.

    Cutting oil is your friend here. It will improve size finish and chip flow.

    Use a vise and lock it down good. An indicator and soft hammer will be needed Tap around to indicate cavity in.

    This project can be done with a good solid drill press. Any spindle play runout or end play will show up in the mould

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    There are some neat things on the Youtube,
    Here is a neat video on how to make a Round Ball mold.




    https://www.youtube.com/watch?v=HgUr-CIS2Cw
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  9. #9
    Boolit Buddy Kegcaissy's Avatar
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    Hi all!

    Mold blocks have been made this afternoon in aluminium. Pins have been inserted and i'm ready to make the cavity. I've tried to make the top face sqared with a file and it wasn't a sucess, a milling machine was used in the end...


    Next step, sprue plate cutter, any suggestions?
    We really need a Ar-15 subforum!

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    ............Suggestions? Well, ground flat stock the width of your mould would be best from 1/8" for small slugs to 1/4" thick. Baring ground flat stock you can buy some inexpensive 1/8" steel and cut to length and then sand flat at least on the side touching the mould. Sand on oiled carbide paper laid on glass, or a granite countertop. Naturally all the holes and such should have already been drilled/countersunk first.

    ..............Buckshot
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  11. #11
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    Just buy the mold you want. You'll spend countless hours and material trying to make something you may not be qualified to make and will end up scrapping it in the end.

  12. #12
    DOR RED BEAR's Avatar
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    You know give it a try you surprise your self. A quality bit sharpened right with a pre-drilled hole close to size should give you something close enough to size.

  13. #13
    Boolit Buddy Kegcaissy's Avatar
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    Quote Originally Posted by RED BEAR View Post
    You know give it a try you surprise your self. A quality bit sharpened right with a pre-drilled hole close to size should give you something close enough to size.
    This is what i'm going to do, i have a beaten up lee mold that will do for a test, i will do it in few steps, already tried it in aluminium; i have drilled a cavity in a piece of aluminium and then cut the metal part in half to see what a bullet may look like.

    On a drill press with a dial installed on it:

    1. Drill to 0.750'' using 5/16'' drill bit.
    2. Drill with a modified 5/16'' drill bit to 0.850'' to get the shape of the bullet, in that case, a flat nose for
    32spl.
    3. Ream with a 8mm (0.315'') reamer to 0.750''
    4. Drill with a P bit to 0.450''
    5. Ream with a 21/64'' reamer to 0.400''

    I'm eager to see if my bullets will be large enough and i hope that this recipe will give me a 180+gr boolit...
    Last edited by Kegcaissy; 05-19-2019 at 10:19 PM.
    We really need a Ar-15 subforum!

  14. #14
    DOR RED BEAR's Avatar
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    Hey tell us how it turns out. You never know what you can do till you try.

  15. #15
    Boolit Grand Master

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    Things aren't right in Oz with your numbers. In line 4 you state drill to .450 then in line 5 ream to .400. Ive never been able to ream a hole smaller LOL Seriously It can be done set up is the big part of this. The more time you spend on forming the drill bit and honing to a dead true form also helps. Piece of thin paper between mould blocks will help the drill to cut centered also. Cigarette paper or a gage paper. Pay very close attention to the center web on the drill as to center and as thin as possible, Off center or at an angle and long, drill will cut oversize and wander.

  16. #16
    Boolit Buddy Kegcaissy's Avatar
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    measurements are the depth of the cut with that particular tool
    We really need a Ar-15 subforum!

  17. #17
    Boolit Grand Master

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    Okay that makes more sense.

  18. #18
    DOR RED BEAR's Avatar
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    Oh no i once bored a 2 inch hole in a 1 1/2 inch wide part. Went to tell the boss that it was drawn wrong and was told what you know better than the engineer . I said no i don't forget i said anything went back put in a 2 inch hole turned it in in two pieces. When asked why i did it i replied i certainly don't know better than an engineer. And that it was made exactly the way he drew it. Boss wasn't all that happy but what could he say.

  19. #19
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    I have made quite a few swaging dies with drill bits. I have also made a couple of molds with drill bits.
    Have you decided on the type of material that you want to use for the molds?
    Aluminum is what the vast majority of home mold makers use. That's because it cuts easily with a "D" bit. I have made my molds from aluminum. But since I use drill bits, my next molds will be made from steel. Steel is far easier to machine in my opinion. Especially when you don't have excellent milling and lathing tools.
    Some advise I would give is ... "sneak up" on the final size. What I mean is make the hole smaller than final size then finish the last couple of thousandths CAREFULLY. You can get hand reamers on eBay. If you shop around a while you will find deals. I found a pack of 10 reamers in the exact size i needed .2244" for I think $11. You can't even get drill bits that cheap. And yes I suggest you finish your mold with a reamer.
    It can be done with a drill bit if you use it like a reamer ...turn the last cut Slowly BY HAND.
    I am not a machinist and will get much flack for writing this but if I listened to all the NEGATIVE responses I got here on how I couldn't do the things I now do on a regular basis, I'd never even TRY anything new.
    With that in mind THE BEST ADVISE I CAN GIVE IS THIS:
    Don't listen to the nay sayers here. (or on any other forum) If you have an idea GO FOR IT. Buy cheap stuff to experiment with and when you get it figured out use better material.
    Good Luck and God Bless.

  20. #20
    DOR RED BEAR's Avatar
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    Well i was a machinist before i retired and i to don't see a problem whats the worst that could happen it doesn't work. Even then you may learn what you need to do to get it to work. Nothing ventured nothing gained.

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