Hi, Guys:
    Guess I'll start something here.  I've got a couple of moulds that the bullets stick in.  There's a well known method of enlarging a mould by coating a bullet with lapping compound and spinning it in the cavity.  However, my bullets are large enough.  Would coating the bullet with JB or Rem-Clean clean up the cavities without enlarging them?
TIA

Bye
Jack

One trick I read about, was to take a smooth but very hard metal cylinder, like a nail set and gently burnish around the outer edge of the mold cavity. Because there was a bit of metal left over from the making, still there.
Another process that I used to free up a mold and aid the filling of the mold was to run dental picks thru the vent lines and the inside of the cavity lines. I begged these dental picks off my dentist with the promise that I was not going into competition with him.
I've also lapped the nose on several of my molds for tighter fit in the barrel, but that's another story.
Jim

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Cast bullets are the true and rightous path to shooting bliss

Jim, this sounds fascinating.

Would you consider writing some of this up, nothing fancy, just step-by-step instructions, for tech note(s)?

I think that this would be useful to a lot of people.

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MikeG

March 25, 2002

From my metal working experience any time I cut, file, turn, bore metal I’m get some sort of a burr. Assuming that God has not singled me out for this experience,  I operate on the premise that metal burrs occur for anybody who cuts metal. Next time you get a new mold get out a magnifying lens and look at the edges, I’m bet you a donut that you’ll find burrs.
When I get a new bullet mold I run my fingers and finger nail all over the inside and outside of the mold to find the burrs. Some times I can feel them and other times I need to use an Exacto knife blade and the magnafying lens to find and cut off the small burrs.
I’ve used nail sets, because they are hardened steel, I’ve used masonry nails for the same reason to gently run around the edge of the mold cavity to burnish off small burrs from the cutting of the cavity. Once I found myself in the dog house because I used the ex wife’s diamond impregnated finger nail file for burr removal. She wasn’t using it at the time!
I’ve placed the mold blocks on a fine Wa****a stone and polished the inside surface to clean off burrs from the cutting of the vent lines. I’ve used a piece of plate glass with some oil and fine abrasive for the same purpose. Sometimes the outer edges of the mold, where the two halves come together there is a burr that will keep the two blocks from joining tightly. Check the alinement pins to see if there is a burr there that will hinder complete joining of the mold halves. The Exacto knife can be used to remove the burr around the alinement pins.
I’ve trued up the sprue plate by polishing it on the same stone or plate glass. The manufacturing process will most likely leave a spot that is pushed out from the sprue hole being drilled. My polishing just cleans up this problem as well as the burrs and sharpens the cutting edge of the sprue plate .
I’ll use dental picks to run down through each vent line to clean out any burrs there. Your dentist will have these dental picks from time to time because the picks wear out, get dropped and he/she will be throwing them out. And where the vent actually intersects the mold cavity whose cutting may have closed the vent line, because the vent lines are cut before the cavity is cut.
The manufactures cannot clean the mold up and remove all the burrs etc and still be able to sell that mold for a reasonable price. I accept this and when I get a mold I take it apart and check it out.
Jim

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Cast bullets are the true and rightous path to shooting bliss

Jim, thanks!

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MikeG

Jack, How much have these blocks cast? Most of the Blocks I own did not start freely dropping bullets till they were used for a couple of hours of casting. As Arkypete mentioned burnish the cavitys and edges. I use a piece of small round hardwood. Are you ladle casting or bottom pouring? Some Blocks like a full throttle fill rate to where others dont. maybe a little slower fill rate would help these two molds. Another option I have used on polishing alum blocks is Tooth paste. Its not aggressive on cutting however small voids can be removed by spinning a bullet in the cavity. Last thought would be the cavitys are not cut on center. Let us know how they work out.
Jim.
PS. after polishing the blocks rinse them well on the outside and use a Q tip dipped in denatured alcohol.

Hi, Guys:
* * One mould is a used and a bit abused Lyman 452630 SWC. The other trouble maker is a new 358665 FN. *I'm using a Rowell ladle. *I suspect I burred the 358665 trying to open up the vent lines. The file I had probably pushed a burr into the cavity. *I've got a knife-edged file now that will cut on the back stroke and it did the job on a couple of other moulds. *Guess I've got a bit of work to do on the first two. *Thanks for the advice.

Bye
Jack

You also mentioned JB and Rem clean.  I use acetone or denatured alcohol  on a small swab to clean molds.  The deburring  mentioned above should be enough, but sometimes smoking the cavities with a butane lighter will help the bullets drop out and won't damage the mold.

Try "smoking" the moulds.  Use a wooden kitchen match, lit of course, to deposit a thin layer of carbon on both halves.  If there is't a physical burr or defect in the cavity this allows the bullets to drop free.  This is absolutely necessary on Lee aluminum moulds.

Howdy Jack-

Polishing the mould using the technique where an abrasive is imbedded in a bullet dropped from the cavity has worked very well for me.  I can't comment about the use of the JB's or Rem-Clean but my own experience came when trying to open up a RCBS .45-70 mould to a larger diameter.

My experience:  
I used a silicon carbide abrasive mixed in some grease - 400 grit.  
The lapping was done by hand.  I drilled a hole in a CB dropped from the cavity just a bit smaller than an allen wrench I had on hand.  Pounded the allen wrench into the hole to create a handle to use for turning the bullet. (This was following the instructions published by a genlteman in "The Fouling Shot".)
Put a small amount of abrasive in the cavity and began to gently close the blocks on the bullet and began turning.
I was afraid of going too fast so I only took about 10 to 15 turns in each direction then cleaned up the blocks and cast a new  slug to check progress.
Result:  Bullet dropped out with no hang-up at all.  The mould had never been so well behaved!  Also - unfortunately for me - the cutting action of the 400 grit was VERY slow.  Actually there was almost no measureable difference in the diameter.
Conclusion - even if you use an abrasive - a fine grit and a limited number of revolutions should help the bullets drop out nicely but won't enlarge the diameter much if at all.

Sky C.
Longmont, CO

When using the method Sky C. describes above, run an appropriately sized tap into the drilled hole and bottom it out. Makes a great stud to chuck in a low RPM drill for lapping mould cavities.

Hi, Guys:
  Thanks for the advise.  I deburred the moulds as Arkypete said and it made a real difference. Now it just takes a light tap to knock the bullets out. Another mould is still cranky, but it's cast less than 200 bullets.  Perhaps several hundred more bullets will loosen it up, as Jim Lambert suggests.

   We haven't had casting weather yet, and yesterday was an exterme example. It started out with 40 mph winds and a dust storm. It started drizzling about noon, changed to freezing rain, then sleet before supper, then snowed after supper. Oh well, any moisture is better than none.

   I think I over-smoked the moulds and plugged the vent lines. Now that they're cleaned out I'm casting at lower temperatures and the bullets aren't as sticky.

   Nice to know that 400 grit isn't that agressive. I've got some of Marshall's 320 grit here and I'll try it if all else fails.

   Incidently, I use muffin pans for ingot moulds when I melt down wheelweights. I found that smoking the pans with the acetylene torch works a lots better than spraying them with Pam cooking oil.

Thanks
Jack