RotoMetals2RepackboxMidSouth Shooters SupplyWideners
Titan ReloadingInline FabricationLoad DataLee Precision
Reloading Everything
Results 1 to 16 of 16

Thread: Boring tooling

  1. #1
    Boolit Master
    Join Date
    Jun 2006
    Location
    Australia
    Posts
    1,159

    Boring tooling

    I want to experiment with opening the dia of several molds I have, what tooling is best, I'm thinking 3/16 dia boring bar ground to shape, what have you guys used?.

  2. #2
    Boolit Grand Master

    Join Date
    Mar 2013
    Location
    Northwest Ohio
    Posts
    14,454
    A boring head with a boring bar in a good solid mill will work. As will the boring bar in a lathe and 4 jaw chuck. Set up is the critical part of this job. Everything needs to be right. You will spend a lot of time indicating everything in.
    How much do you want to increase the size of these moulds? If only .002-.005 then lapping it may be a better option here.
    I have modified moulds with a jig bore, Bridgeport, EDM, and lathes. The EDM was the easiest a undersized carbon electrode turned to match the bullet with changes then the flat circle program written and ran. A lot depends on what you have available to you machine wise. With set up a boring head in a drill press will do it but the stop is a pain to deal with.
    For the boring bar I would hand grind one from an end mill for the boring head. the cutting face would look like a parting tool and be the width of the bands since you cant start above and feed down for a straight surface. Your boring head will determine the size end mill you use.

    The last option is to make a new cherry with the changes and install longer pins and space blocks open, then cut half at a time. This actually can be done pretty easy with aluminum blocks as Unhardened tool steel ( or pre hard) will cut aluminum or brass one offs.

  3. #3
    Boolit Master
    Join Date
    Nov 2017
    Location
    brisbane ,qld,australia
    Posts
    2,125
    Ive taken the gas check groove out of CI moulds...RCBS and Lyman.......you can also take the last lube groove out easy......but machining around the lube grooves would be a very good reason to have a DRO......which I dont........CI moulds are accurately finished on the outside,and so easy to set up.,which others may not be.....I have just setup in a 4 jaw and dialled them in....a very delicate touch is needed,its easy to overcut......which I did on the first one I tried a Lyman 427215 ended up 434 where the check was...after that I was a lot more careful,and managed to get the finish bang on..........in fact the 45/300 could have done with being a bit oversize for the Marlin,but I didnt think of it at the time.

  4. #4
    Boolit Master
    Join Date
    Jun 2006
    Location
    Australia
    Posts
    1,159
    I mostly shoot military rifles with over size bores/throats, what I would like to do is gently re-cut the bands to suit them, or in the case of molds such as Lymans 324366, open the nose more to give a bit extra support. Another option is to make bump dies.

  5. #5
    Boolit Master
    Join Date
    Jun 2006
    Location
    Australia
    Posts
    1,159
    Quote Originally Posted by country gent View Post
    A boring head with a boring bar in a good solid mill will work. As will the boring bar in a lathe and 4 jaw chuck. Set up is the critical part of this job. Everything needs to be right. You will spend a lot of time indicating everything in.
    How much do you want to increase the size of these moulds? If only .002-.005 then lapping it may be a better option here.
    I have modified moulds with a jig bore, Bridgeport, EDM, and lathes. The EDM was the easiest a undersized carbon electrode turned to match the bullet with changes then the flat circle program written and ran. A lot depends on what you have available to you machine wise. With set up a boring head in a drill press will do it but the stop is a pain to deal with.
    For the boring bar I would hand grind one from an end mill for the boring head. the cutting face would look like a parting tool and be the width of the bands since you cant start above and feed down for a straight surface. Your boring head will determine the size end mill you use.

    The last option is to make a new cherry with the changes and install longer pins and space blocks open, then cut half at a time. This actually can be done pretty easy with aluminum blocks as Unhardened tool steel ( or pre hard) will cut aluminum or brass one offs.
    That's what I was thinking of doing.

  6. #6
    Boolit Grand Master

    Join Date
    Mar 2013
    Location
    Northwest Ohio
    Posts
    14,454
    I believe lapping would give you what you want the easiest.
    Lapping would only require some modified bullets a t tap handle and time.
    Cast a few good bullets from the mould softer here is better as it impregnates the compound easier and holds it better.
    Drill a blind hole in the base of the bullets and epoxy a 1 1/2" length of 1/8" key stock in them.
    Heat up your lead pot and have it on the bench handy. Also some solvent in a container to clean blocks and some light oil
    2 flat steel plates to impregnate the bullets with.
    Start with 240 - 280 grit compound. Spread a light coat on one plate place a bullet on it and roll between the 2 plates with moderate pressure. This press the abrasive into the bullet impregnating it.
    Gently place the bullet in the blocks and with a tapping style motion ( turn back and forth 1/4 turn rotating 1/4 turn thru 3-5 revolutions). Clean and warm mould cast a few bullets check for size and finish.
    Depending on size either repeat the 240-280 grit again or move to 320 grit and repeat above.
    Next depending on size of bullet is 600 grit as above.
    The hand turning back and forth with partial rotation keeps bullets round.
    Occasionally a drip of light oil restores the lapping compound and improves finish

    I hold the blocks in a drill press vise sitting on the bench when lapping.
    I also like to do a finish with flitz, or auto rubbing compound when to size.
    Its easier to remove metal then replace it work slow and carefully check size often. On this project .001 removed is .002 on bullets dia.

  7. #7
    Boolit Master
    Join Date
    Nov 2017
    Location
    brisbane ,qld,australia
    Posts
    2,125
    To do what you want by machining would be very difficult with long 8mm bullets.............lapping is one answer.........if you reject lapping,then I believe you could alter the moulds in the way you want by using old fashioned die sinking techniques......one half at a time......Pre CNC,this is how intricate plastic injection moulds and mazak die casting dies were made..........just have a look at a old Matchbox diecast model to see what can be done.

  8. #8
    Boolit Master
    Join Date
    Apr 2005
    Location
    sulphur springs, Tx
    Posts
    1,243
    Country gent:

    thanks for your description! I've a bore riding design that is small in the nose; I'll give lapping it up about .003" a try.
    Decreed by our Creator: The man who has been made able to believe and understand that Jesus Christ has been sent into this world by the Father has been born of the Spirit of God. This man shall never experience spiritual death. He will live forever!

  9. #9
    Boolit Master

    Join Date
    Feb 2007
    Location
    Lewiston, Idaho
    Posts
    2,732
    Most of the molds I have made were done on the lathe but I have done a few in the mill with a boring head. Start with making a cutter shaped like the bullet you want but small enough in diameter so it can clear the grease grooves. grind half of it so it looks like a "D" reamer. My boring head takes 1/2" diameter so it was easy to make up the cutter out of drill rod. After lining everything up in the mill, the two halves are are drilled to the miner diameter. The boring head is installed without moving the table X or Y. The cutter is run down into the block and adjusted out a few thousandths at time and the mill is turned on and off. This will not work for pointy bullets. I made a double cavity mold block for an automatic casting machine and the two cavities were within 2 grains. It is easier to do it in the lathe because you don't have to stop it to make adjustments.

  10. #10
    Banned
    Join Date
    Apr 2010
    Location
    SE Iowa
    Posts
    679
    I have used what used to be called outlaw boring and facing head that by holding the ring feeds out .0001 per rev

  11. #11
    Boolit Grand Master

    Join Date
    Mar 2013
    Location
    Northwest Ohio
    Posts
    14,454
    We had several of those made it nice since you could bring the bore to size and then face in to make a square bottom. Ours could be set to feed in or out with clockwise rotation.

  12. #12
    Boolit Master
    Join Date
    Mar 2005
    Posts
    4,612
    I would recommend some process development first.
    Experiment on some practice mold blocks until you have confidence you can go through the entire process without a false move.
    EDG

  13. #13
    Moderator

    W.R.Buchanan's Avatar
    Join Date
    Mar 2011
    Location
    Ojai CA
    Posts
    9,872
    I would like to inject some reality here. First if you are using a Boring Head and you want to increase the diameter of the driving bands you aren't going to be able to do that because there are little ridges between the driving bands. You can't just plunge down and make your desired diameters.. You have to set the diameter before you turn the spindle on and you can't feed the tool in during the process, only when the spindle is stopped. If you had a boring and facing head you could. I sold mine to Seagiant. I never used it in 20 years.

    Moulds are now made with tools that are shaped like the bullet only smaller and then Circular Interpolated on each half of the mould blocks independently.

    Lapping the mould would be the easiest way to do a decent job on increasing the size of the mould.

    Randy
    Last edited by W.R.Buchanan; 12-25-2018 at 05:21 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!"
    www.buchananprecisionmachine.com

  14. #14
    Super Moderator




    Buckshot's Avatar
    Join Date
    Mar 2005
    Location
    So. California
    Posts
    11,833

    Lathe vs Milling machine

    ..............I've always found that LATHEBORING is the easiest. Others must agree because if you read the adds they'll usually say, "Lathebored". The lathe is the machine on which it's most easily accomplished. I have to add here that the lathe is easiest when MULTIPLE tools are needed to create your bullet design.



    In the lathe, if there is more then one cavity to do, unless you have made up the specialized tooling to accomplish the repeatability, you may mount the mould to a fixture on a simple faceplate. When moving the blocks you'll need to indicate in the next hole, if using a simple vise as shown, then simply tighten the vice. This little vise is a very NICE vise too. Being off center you will not be able to spin it at high speed (unless you're maybe using an American Pacemaker lathe, previously used to turn propeller shafts). My 11" Logan isn't in the same class:



    I have produced some moulds on my Bridgeport clone milling machine, and it is more of a 'PITA' then the lathe, but do-able. My mill has a 3 axis DRO that is good to .0002" so that helps too. I simply prefer simpler stuff to use on the milling machine.

    BELOW: Is a set of blocks I produced for solid shotgun slugs for use inside a 12 ga shotcup.



    It only required one tool. A lot of my boring tooling is simply HSS drill blanks, or shanks cut off of aircraft drill bits, like this one.



    Since the tool I was going to use would be used in a boring head, I didn't want to have to monkey with adjusting the BH for multiple cuts in each hole, so I used a bit after which all I had to do was to plunge straight into each cavity with a slightly modified drill bit (to produce a flatter face).



    All the dimensional data (for this it was just the X and Z data) and then plunged in the previously shown tool to the noted depth.



    It is a LOT more work to setup a boring head for repeating work like cutting in lube grooves using a milling machine, because you have to use a rotary table. The problem there is simply humping the %$#^* heavy SOB up onto the mill table, then indexing the work and then finish bolting it down! Doing the same thing on a lathe is a walk in the park (no rotary table!!!).

    ...............Buckshot
    Father Grand Caster watches over you my brother. Go now and pour yourself a hot one. May the Sacred Silver Stream be with you always

    Proud former Shooters.Com Cast Bullet alumnus and plank owner.

    "The Republic can survive a Barack Obama, who is, after all, merely a fool. It is less likely to survive a multitude of fools such as those who made him their president."

    Shrink the State End the Fed Balance the budget Make a profit Leave an inheritance

  15. #15
    Super Moderator




    Buckshot's Avatar
    Join Date
    Mar 2005
    Location
    So. California
    Posts
    11,833

    More mould stuff

    ...........Where the milling machine shines is in making up your mould blocks. I simply use 6061 alloy aluminum bought from MSC in 6' sticks. Two pieces are set in the band saw and parted off in pairs with about 1/8" extra length. Then each pair gets a number lightly stamped on the outside of each piece in the pair.

    Then they go into the milling machine where a scant bit is milled off one end:



    After one end is done on each set, a work stop is set up on the stationary vise jaw and the finish cut is made. This will bring each set of blocks to .002" or less in length for the sets being made. After that about 4 sets of blocks get set on parallels, locked up in the vise and the handle slots are cut:



    After they're all done on both sides, it's then time to drill for the alignment pins. A work stop is clamped to the vise and they're drilled one set at a time:



    Next up is to drill for the handle pins:



    The only thing to do after that is to D&T for the handle pin setscrews. Then they get zip tied together. Since the blocks are aluminum, the holes on the female block get a stainless insert so there isn't any steel on aluminum interface.



    The left block has the steel insert in the top right hole and the right block half has the inserts in the upper right and bottom left holes. This 3 cavity mould is an adjustable cavity type for making 'Lead Cores' to use in a swage die.

    If you're gonna be making bullet moulds you'll need to create some "Implements of Destruction" to remove the material that doesn't look like the boolit you're wanting. I have no fancy grinding equipment. I have a bench grinder, and the only concession toward 'Fanciness' is a diamond grinder. Kind of like the bench unit, only it takes diamond abrasive wheels.



    The cutters are called 'Spoons'.



    One like this could just about be stuck straight in (carefully as a lot of the edge will be cutting), and after the minor diameter portion of your boolit was finished, you'd then insert another tool to cut the drive bands, or the MAJOR diameter. In essence you're single point cutting your slug design.



    On withdrawal the tool will be coated with metallic mud. In the photo in case you're wondering why the blocks don't look square is because I'm boring a swage die (which is round ).

    ..............Buckshot
    Father Grand Caster watches over you my brother. Go now and pour yourself a hot one. May the Sacred Silver Stream be with you always

    Proud former Shooters.Com Cast Bullet alumnus and plank owner.

    "The Republic can survive a Barack Obama, who is, after all, merely a fool. It is less likely to survive a multitude of fools such as those who made him their president."

    Shrink the State End the Fed Balance the budget Make a profit Leave an inheritance

  16. #16
    Boolit Master

    sparky45's Avatar
    Join Date
    Apr 2010
    Location
    SE, KS
    Posts
    2,405
    Good stuff Buckshot, keep it coming.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Abbreviations used in Reloading

BP Bronze Point IMR Improved Military Rifle PTD Pointed
BR Bench Rest M Magnum RN Round Nose
BT Boat Tail PL Power-Lokt SP Soft Point
C Compressed Charge PR Primer SPCL Soft Point "Core-Lokt"
HP Hollow Point PSPCL Pointed Soft Point "Core Lokt" C.O.L. Cartridge Overall Length
PSP Pointed Soft Point Spz Spitzer Point SBT Spitzer Boat Tail
LRN Lead Round Nose LWC Lead Wad Cutter LSWC Lead Semi Wad Cutter
GC Gas Check