Sprue plate

[exblaster]

I need to make a sprue plate for an old mold. what problems can I expect that may not be obvious ? This is my first attempt at this sort of thing.
Thank you for all comments.
Exblaster

[45nut]

What brand of mold? Gussy,,,look for the Casting Stuff link below...makes superb replacements for Lymans.

[exblaster]

The mold is a Springfield U.S. issue type mold. The only markings are 50-70 and a small eagle. it has handle that look like a pair of tin snips made in one piece with the mold blocks. I need to make a sprue plate for this mold as the original is missing. would like to know if thin or thick plate is best and should the plate be hardened?
Thanks for any help Exblaster

[BABore]

I like using 3/16 O-1 tool steel for plates. You need the thickness to get an adequate countersink diameter for a nice size sprue. A big bullet like that will suck a lot of lead when cooling. Use a 90 degree c'sink cutter if available, but a 82 degree will work. Put an 1/2 inch min. aluminum backer under the sprue plate and spot your hole with a center drill. Drill through the plate and backer with a bit that's one size under your desired hole diameter, about a #22 (0.157) bit. I shoot for a 0.160 finished diameter so a #20 or 21 bit. Go slow with the C'sink tool and cut the hole until your almost cutting out the drilled hole. Finish the underside with a hone. to remove any burr or pucker. It will still pucker out a bit and that's the reason you go a little undersized with your bit.

When your done, file then stone a leade and slight radius on the plate edges. This keeps the swinging plate from tearing into the top of the mold blocks.

[exblaster]

BABore thank you fore the help will do as you suggest.

exblaster