How to add vent line in mold?

[dogdoc]

I have a mold I want to try to vent a little better on the cavity nearest the bolt that holds the sprue plate on. The base will often not fill out unless a high pressure stream of lead comes out. Has anyone added a vent line?

[44man]

Hold a straight edge on the block and scribe some lines with an exacto knife. Then gently rub the face on some 400 grit paper on a flat surface to make sure you didn't raise a burr. You can also just deepen the grooves already on the mold too with anything that will cut the block. Aluminum is easy but cast iron needs a hard tool.

[Bass Ackward]

I have a mold I want to try to vent a little better on the cavity nearest the bolt that holds the sprue plate on. The base will often not fill out unless a high pressure stream of lead comes out. Has anyone added a vent line?

DD,

You are in luck. You don't have to worry about a method for cutting a vent line. Since the problem is your base, just take a stone and put an ever so slight bevel on the top of both blocks. I would do this for both cavities. Less chance for a screw up.

[D.Mack]

Are you leaving a puddle, above the sprue hole? If not it may be just sucking air under the sprue plate, instead of liiquid off the sprue plate as it solidifies. D.Mack

[dogdoc]

Bass Ackward

Can you elaborate on what you mean. I do not follow. Thanks

Sonny

[44man]

OOPS, guys got the best of me, old age ya know. Just take a real fine file and break the sharp edge on the inside top of each block. This will let air out right at the sprue plate. Don't take much off, just touch it lightly.

[Bass Ackward]

Bass Ackward

Can you elaborate on what you mean. I do not follow. Thanks

Sonny


Sonny,

Just like 44man said. Where the blocks come together at the top is your problem. All you want to do is break the sharp edge. Now if you feel comfortable, this can be done easily with a file. If you are impatient, then use a sharpening stone so you don't get carried away. The idea is that you just want to see a little shine from each half. Then check that your sprue plate isn't too tight. It should just fall of it's own weight when the mold is cool.

All you are simply doing is putting that "vent" line where it will do the most good. And that is at the top. This way you don't have to worry about buggering up a cavity that can cause a burr and make removing bullets a living hell.