RotoMetals2Graf & SonsRepackboxInline Fabrication
WidenersStainLess Steel Media

Results 1 to 10 of 10

Thread: Mould base-band enlarging?

  1. #1
    Boolit Master
    Join Date
    Mar 2010
    Location
    Michigan
    Posts
    1,166

    Mould base-band enlarging?

    Who would you recommend for enlarging base-band dia. .004"? Thanks!

  2. #2
    Boolit Grand Master

    Join Date
    Mar 2013
    Location
    Northwest Ohio
    Posts
    9,495
    .004 out of an existing mould is going to be a job, not in the removal but in the set up ( everything will need to be perfectly lined up) Then the touch off of the cutting tool will be critical. WHile your saying .004 out of the mould that's .002 on a side.

    You could lapp it out with out to much trouble. Lapping would just the base band would require only impregnating the base band with compound and leaving rest bare.

    A couple flat plates 1 1/2 wide 3-4" long and 1/4"-1/2" thick Put a shallow rail down the long edge of one 1/8" above surface. This is the rail to align the bullet on location.
    Cast a couple 3 good bullets from each cavity
    Drill a hole centered on base a piece of 1/8"X 2" key stock just fits into, and glue a piece into each bullet. Epoxy works very good but I have used super glue also.
    put a very light smear of compound along rail as wide as band. lightly finger roll 1st bullet thru this and move over and roll between 2 plates to literally press the grit into the bullet making your lapp.
    start with a grit around 280 to rough with. remember you only need to remove .002 on a side.
    Gently insert lapp into one half of the blocks and close tightly. I clamp them in a small drill press vise.
    A T handle tap handle and work bullet/lapp in a tapping motion back and forth 3-5 times 3/8-1/2turn rotate 1/4 turn and repeat this thru 2 rotations. check progress here at this point. Open and remove lapp, clean blocks. Visually inspect the cut if bright shiny area is close to 100% measure it or better warm it up and cast a few bullets measuring them.
    Here its a judgement call to work closer with the coarse grit or go finer depending on measurements sizes.
    Next grit would be some thing 320-400 to just barely under size or to size Again casting a few bullets and measuring is preferred
    My last run once very close to size or to size is 1 full rotation cycle with flitz or shimichrome polish. Tooth paste will also give this fine polish. Here you can either do the compete cavity or just the band.

    Some tips to help the lapping process go smother.
    A small drop of light oil on the lap helps the compound to cut cleanly and evenly. Here a light drop on a q tip and wiped into the cavity before inserting lap.
    the back and forth rotation maintains cavities location and makes a very round cavity.
    Having a small lead pot up to temp at the bench speeds checking sizes up. Clean and dry mould sit on top of pot to warm for 4-5 mins dip corner till lead dosnt stick and cast a few 8-10 good bullets cool and measure. I prefer to ladle cast for this but that's me.
    Lapping is done with the softer material cutting the harder material. The soft lap impregnates with the abrasive and becomes a cutting tool the soft material then cuts the harder material with the abrasive since its holding it.

  3. #3
    Boolit Master


    Join Date
    Mar 2005
    Location
    Perryville, Ky,USA
    Posts
    3,966
    Any good machinist with a CNC mill can do that in about 10 minutes. Square mould, dial in outer edges and make .001" cuts until you get what you want. Basically the way we remove GC shanks./beagle
    diplomacy is being able to say, "nice doggie" until you find a big rock.....

  4. #4
    Boolit Grand Master

    Join Date
    May 2005
    Location
    Castlegar, B.C., Canada
    Posts
    6,121
    It could be even easier depending on caliber. You can likely buy a reamer to suit if you look at standard sizes, metric, decimal and letter sizes. A little larger won't hurt anything (like a thou or two). all you need is a drill press to line things up then turn reamer by hand. Chucking reamers should be pretty inexpensive... like $15 to $20.

  5. #5
    Boolit Buddy oldhenry's Avatar
    Join Date
    Mar 2016
    Location
    Albany, GA
    Posts
    289
    The information by county gent is excellent.

    Henry
    Last edited by oldhenry; 01-05-2019 at 10:30 PM.

  6. #6
    Boolit Buddy
    Join Date
    Mar 2010
    Location
    NC Arkansas
    Posts
    456
    Quote Originally Posted by oldhenry View Post
    The information by County Agent is excellent.

    Henry
    Spell his name right so he gets proper credit, I'm sure country gent would appreciate it.

  7. #7
    Boolit Master

    Join Date
    May 2015
    Location
    easternshore of va.
    Posts
    1,954
    I spoke through PM with a member Willicd76 about a bit of work on a few molds I want to play with , and his price seamed very reasonable . I haven't done it yet so I can't really say how it worked out but this thread reminds me to get them in the mail . Send him a private message and ask .

  8. #8
    Boolit Buddy oldhenry's Avatar
    Join Date
    Mar 2016
    Location
    Albany, GA
    Posts
    289
    ulav8r,

    Done. Thanks for the heads-up.
    Henry

  9. #9
    Boolit Master
    Join Date
    Nov 2017
    Location
    brisbane ,qld,australia
    Posts
    618
    I cut the gas check groove from all my iron moulds............simply set up with a dial gauge,and skim.The first one was a Lyman 427215,and I overdid it ,ended up about 434,after that I got the hang of the light touch needed,and did a dozen two cavities in a couple of hours..............A friend had done Lee 2 cavities by cutting the handles ,rather than punching out the pins....he also turns the 458HB into a smooth PP 462 or a single groove 472 FB.

  10. #10
    Boolit Grand Master

    Join Date
    May 2005
    Location
    Castlegar, B.C., Canada
    Posts
    6,121
    I should add that the reamer idea assumes a PB mould. Otherwise you are into precision machining or lapping the mould per country gent's post.

    Looks like you may have it under control at this point.

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