Proper location for chamfer to vent bullet base

[10mmShooter]

He Guys,

In the quest to improve bullet base fill out. I want to chamfer my mould havles just under the sprue plate to vent the bases better.


In my pic I understand I should chamfer the top edge of each mould half. I have indicated in red. Should I also chamfer the edge that is between the two cavities as well(indicated in green). I'm thinking I will just do the two edges in red first?? Also should I try to chamfer just one mould half first? then test and before chamfering the other mould half??

What do you guys think??

Also how much is the chamfer?? I'm thinking I'll just knock the corner off something less than 1/1000 th inch chamfer. I'm going to us a fine sharpening stone to knock off the edge. I dont have a fine enough file to do the job.



http://www.keithrussell.net/venting.jpg

[Doc Highwall]

I do both halves all the way across with a stone just enough to see that there is an edge break .002"min -.005" max. and make sure that the sprue plate is not to tight. Some times after when you get the mold up to temperature you will find that you will have to re-adjust the sprue plate. I also stone the bottom edge of the sprue plate where it slides off and on the top of the mould.

[HeavyMetal]

+1 for Doc's suggestion to make sure the bottom of the sprue plate is smooth and flat!

Plate tension can be all over the place, I like it so that I have no up or or down flex when the plate is in pouring position but has some light "drag" so that it won't open as you turn it side ways.

As for filling out base areas?? Many have suggested dipping the corner of the mold in the pot of alloy to bring it up to temp but I seem to be the only one suggesting that you dip the sprue plate as well!

Dip the area you would strike to open the mold and hold it in the alloy until the lead desn't stick to it, then cast!

I've found this works very well with HP molds and since I managed to start doing this my reject rate with any mold, due to rounded base's, has fallem to the 1% or less area!

When doing HP 429421's I've found dipping every forth cast keeps my mold just right.

Try it and see what happens!

[Bret4207]

I'd get my mould nice and hot before chamfering. I mean get it HOT and see if that isn't the problem. Cast faster and keep the mould closed as much as possible. I've seen videos of guys casting and they spend way too much time with the mould open gawking at boolits. You want things hot. If you really feel the best thing is to chamfer then just a couple strokes with a stone is all you want. Try again, a couple more if it's still not working. That's it, no more.

[excess650]

I pressure cast with a ladle, and have no problems. If you're bottom pouring, try making the metal hotter, and leaving a good sized sprue puddle on top. Your mold blocks don't appear smooth on top, so should be venting just fine.

[Echo]

+1 for the Doctor's treatment. Stone just enough to see a bright line, and do it on both halves, and do it between, also...