enlarging the cavity in a bullet mold

[4ster]

I have a brass .610 round ball mold that I would like to enlarge to .620 or so.  Can this be done without making a steel mold cherry?

Right now it throws a ball that has a long sprue so there is room to make the cavity larger.  Can I make a mold cherry from a ball it cast and use some grinding compound to enlarge the cavity or will this just make the ball smaller?  I also have  .615 RB that i could use as a step up when the cavity starts to enlarge were the smaller ball is not as effective.

[C Wallingford]

I have done that but, the problem is keeping it round or spherical. Mine ended up being slightly football shaped. It shot fine but kinda looked crazy.

[D. Taylor Sapergia]

I once cast a babbit ball in an aluminum Lee mold, ran a screw in through the sprue hole, and with lapping compound enlarged it from .457 to .459 to better feed my Colt Walker.
But to increase .005", you might need to use a cherry.  Great project.

[Daryl]

Concur! A VERY hard lead ball would be best for the system Taylor indicated. Rotating the ball around inside the cavity while it's spinning (from the handheld electric drill? might help a lot to achieving a round-ish ball. Switching to a .615" ball will help further.  .010" is a long way to go., I think, but not impossible, with time and patience.

[Bob Roller]

Babbit? Can it be used to harden a bullet? I have some and have wondered about its use
other than for old cars or farm machinery and sawmills.I worked at a shop that did repair
on babbit bearings and poured new one when needed. One we did was so heavy it took a big
Ford 4x4 with a diesel engine to move it. We poured it and finished it on a BIG VTL (Vertical
Turret Lathe).Hardening bullets for a 45-70 was what I have in mind.

Bob Roller

[smylee grouch]

I did the same thing as Taylor with a 562 Lee mold. Then after giving it a spin with lapping compound I cleaned it up and cast a new ball and used the new ball to do it all over again and cleaned it up again and cast another new ball and did it over again this same way several times. It worked but I never measured the different diamiters on the new ball to see if they were concentric. It took a long afternoon to do the project.

[D. Taylor Sapergia]

Bob, babbit has nickel in it.  It doesn't take much to harden a pot of lead.  I'd prefer to use tin for that job.

[Habu]

It will depend on the composition of the babbitt you have.  From what I've seen, the stuff that used to be used for bearings in engines was a 89% tin/7% antimony/4% copper alloy; this stuff worked great for hardening bullet alloys (particularly for those destined to be heat treated).  The stuff used for motors (and windmills, pumps, etc) in my experience has been 80% lead/15%antimony/4% copper; this works well in bullet alloys when cut 1:1 or 2:1 with pure lead. 

Sometimes what you have is a mix.  When I poured new bearings for a friend's old Crescent bandsaw, I used the same alloy I used the year before to do new bearings in an old wind mill.  It is nothing more than a mix of new babbitt and the stuff I've removed from projects that have been re-babbitted (and a couple of pounds of linotype years ago when the pot was low and I wanted to be sure there was enough alloy).  I'm really not sure what all is in it--lead, copper, tin, antimony, maybe even nickel (but the various sources were old enough I'm not sure how much nickel, if any). 

If you've got new metal, it should have a label with the alloy content.  If it is used metal, you'll have to experiment a bit. 

[Bob Roller]

The babbit I have is new bars but they are marked Diesel Marine
and I was told that was a brand name and not a specification.
When I worked at American Babbit Bearing the alloy was Copper,Antimony and Tin
but I don't knw the percentges.I will experiment with a 500 grain bullet called
a Schmitzer which is a spire pointed design form a Lyman mould.

Bob Roller

[2lookindown]

If the spure is the problem ? Have someone mill the top of the mold down a few thousands.... Then the ball stays the same size and shape...

[4ster]

If the spure is the problem ? Have someone mill the top of the mold down a few thousands.... Then the ball stays the same size and shape...

No, I want to cast a larger ball.  This mold is a ball size I don't use and there is room for a larger ball in it without the resultant flat spot that would appear if doing this to a better laid out ball mold.  

I could ask Jeff Tanner to make me a custom mold  in .620 but what is the fun in that?

And thanks everyone for your useful comments.

[2lookindown]

 I C

[Hungry Horse]

 My dad, who was born in 1907, hung around a mechanics shop as a kid, that built model T engines( converted to overhead valves) to race in boats on Lake Merritt, in Oakland. Everyone that race against the shop owner, lost, because his engines stay together, when others failed. One day my father was there when he was about to pour some main bearings in his engine. He swore my dad to silence, and started his big old plumbers lead pot. After letting it heat to a very high heat, he looked around furtively, and dropped in a silver dollar, let it liquify, and then added his babbit.   After the bearing material had melted, he skimmed the dross off, and then stirred the pot with a small bundle of carpenters pencils that had been sharpened to expose about 4 or 5 inched of lead. This attracted a lot of impurities that usually would wind up in the bearing. My dad  related this story to a friend, that was pouring bearings for his steam powered, sternwheeler, tour boat. It work like a charm.

                         Hungry Horse

[redheart]

I've also heard that you could pour lead into your mould and insert a small rod into the sprue hole while it's still liquid to make something you could insert into a drill and then use grinding compound and spin it in your mould to enlarge it.
You could also drill a hole in a cast ball and screw in a large sheet metal screw and get the same effect.
Lead just might hold on to the grinding compound better and work a little slower and so perhaps stay more round plus they would be so easy and cheap to make that when it wears out you can easily make another.
I've never done it so it could be worthless info.

[JB2]

Well, if you do it with the 'lap' method, please take pics and post them.  I bet I'm not the only one interested in seeing how it turns out, how long it takes, all that good stuff.  Just like lapping a barrel, without all them pesky grooves! 

[Hungry Horse]

 I have used the method mentioned to clean up some of those old Dixie cast iron hair straightener molds that had machine marks in them, but never carried it to the point of enlarging the cavity. Clover valve grinding compound is what I used. The shaft used to attach the ball to the drill needs some teeth of some sort to keep it from spinning loose.

                     Hungry Horse

[David R. Pennington]

You lap with the grinding compound till it feels like it's not cutting anymore, then you clean it up and cast another ball and start over. Each time the ball gets a little bigger.