Alloy in Pot Query

[edctexas]

I just added some Rotometal Merit Babbit alloy to my pot. I had essentially 18.5 LBs of COWW and added 1.5 lbs of the babbit. But when the pot cooled it looked funny. It has a cavity in the middle. Please see the picture attached. As the alloy melts, I get bubbles (lumpy gravy) at about 620-630F. When I reduce using beeswax, I get a normal shiny smooth surface.

What does the cavity indicate? Too much antimony? Not enough tin? Using the calculator spreadsheet I though I was getting about 3% Antimony and 2% Tin. The boolits cast seem slightly frosted at 715F. I have some problem now with the base fillout.

Any suggestions other than send you the alloy and let you play with it? Do I need to get it tested for composition? I was trying to get a harder alloy for rifle and 9mm.

Ed C

[runfiverun]

it indicates you didn't have a sprue for the pot to draw more alloy in and it killed your fill out leaving a void.

the other stuff [grey foam] is your antimony needing to be fluxed in the alloy.
when you see that turn the heat up and flux the melt real well.

all that crystalline stuff you got there indicates a high antimony alloy.
if your basing your measurements on a lee 20 lb pot and an ingot mold your numbers are waay off.
the lee pot only holds 18 lbs to the brim on a good day, and an ingot mold only holds a pound of alloy if you got it domed up over the top and it's filled all the way up the sides.

[bangerjim]

UR fine. Just dilute with pure. As said by run above, too much Sn & Sb based on your assumed weights.

WEIGH your ingots!

And use beeswax to reduce in your casting pot to put the elements back into the mix.

banger-j

[edctexas]

Thanks guys!! Tried adding Pb and it seems better.

Ed C