Paint with a magic marker the top before you start so you can see if you are leaning towards one side or the other!
Paint with a magic marker the top before you start so you can see if you are leaning towards one side or the other!
Figure 8's on a flat surface with the 180 and 220 glued down with steady, even pressure. 280 and 320, no need to go much finer in my view, it's a mold not a mirror. Of course, if you have a mill and the skill to use it, it is easy-peasy. As has been said, it is a 10 minute job then. But sand paper will work, and it won't take too much time. That lee aluminum is soft.
And just as a hint, don't forget to clean up the sprue plate as well. I won't say how I now know, but trust me, you don't want to make extra work for yourself.
_________________________________________________It's not that I can't spell: it is that I can't type.
I’ve repaired one like this with a Lansky knife sharpening stone. I have the 5 stone kit, and I used the 2nd finest grit (red stone). It is necessary to confirm your stone is flat, and not all 5 of mine are flat.
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It was not necessary to remove enough material to completely remove the gouges. Just polish off the high spots and it works fine… a little bonus venting to help cast square bases.
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You have burrs protruding into your cavities now, and how you choose to repair this may create more burrs. The stoning method does not create burrs, but the stone is good for removing burrs. You will want to be very gentle here. I basically used the weight of the stone only, and did not apply any additional pressure by hand. Burrs gone, mold works.
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A more gentle way of removing burrs is to get a biodegradable butter knife (from Stackman on Amazon), and rub the face of the mold with the side of the knife. What you are doing here is using the edges on the mold to shave material off the biodegradable knife. This is a slow process, and it would be a challenge to harm your mold with this method.
Knock down the high spots but no more using a piece of glass with a piece of 600 wet or dry taped to it. Polish the bottom of the sprue plate the same way. Then lightly leement the bottom of the mold cavity.
+1 on using a lathe. Much easier to find someone with access to a lathe, than a mill.
You don't need a 4-jaw adjustable chuck ; a normal 3-jaw will do. Just make sure one of the claws are perpendicular to the cavities
It doesn't matter if the mould is way off center as long as the top flat is parallel to the chuck face.
Cap'n Morgan
Be very careful of lapping or grinding these. It is really easy to get the geometry totally out of whack.
I would clean up any lead residue and just try casting with it before you do anything else. Next step would be to is use a shot of dry mold release in the rough area to lube and sort of clog up the gouges. They look bad, but are probably smaller than you think. They may not really even cause a problem so long as the sprue plate is in good shape.
I definitely would cast a bunch of boolits first, and, if they cast OK, see how they load and shoot. It may be that the marks at the side of the boolit base will iron out in sizing/lubing, or, if they don’t, lapping the first band of the cavity slightly might minimize or eliminate the marks.
As long as the sprue plate lies flat on the blocks and no metal flows into the galled area, I’d just treat the situation as cosmetic and ignore it.
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Attachment 300322 Attachment 300323 I'm glad I read this thread. I had a few thousandths milled off the top of the mold blocks and now the mold is good as new. The gas check shank is still plenty long enough. Always such good information on this site.
I had a couple I needed to fix a little bit. I started at 220 and then finished with a 400 grit.
ive got very similar to what moa shows us. its a Lyman 429667 dont remember where I got it, but was thinking a surface grinder or mill with a fly cutter would clean it up. since ive got a couple others including my current favorite mp 432640 ill probably put it up on S&S since I no longer have a surface grinder or a mill.
Looks great Barry, nice save.
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An old mirror with a peeled silver coat ,couple of sheets of good quality abrasive paper ,and maybe 10 minutes .....and use a bit of beeswax on the sprue plate pivot while casting.......RCBS moulds are made of soft cast iron,not much harder than ally moulds(should say used to be......they are steel now.)
If you haven't fixed it already, maybe search craigslist or something for some granite counter cutouts. I picked up a couple really cheap just for lapping. They are plenty flat enough for these purposes. As said, use figure-eights and swap end for end constantly. Dont apply a lot of pressure, just a nice even pressure or the corners will round off.
Or ship it to me and I'll fly cut it on my bridgeport for free...if you dare!
Good deal. You might check the hole edge for burrs.
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 |