Rounded boolit bases

[Hawkeye45]

A little help please. I have a Lyman 452 mold that one cavity (out of 2) will not cast a sharp base. The other one casts fine. I have used temps ranging from 600 to 800 on the thermometer. Using a RCBS bottom pour with 10 to 15 pounds of alloy and pour a sprue as large as will stay on the mold without going over the side. Other molds work well with this alloy. Any help would be appreciated.

Remember Pearl Harbor day, think about the cost of our freedom.

[mpmarty]

Sprue plate venting problem.

[Bullshop]

Put a slight bevel at the top parting line and the improved venting should solve it.

[MtGun44]

Might try loosening the sprue plate a touch, too.

Bill

[runfiverun]

if it's the cavity closest to the screw then loosening it a little will help, if it's the further one a little tightening could do it.
if that don't do it, then breaking the corner of the mold with a stone like Dan suggests will.

[williamwaco]

if it's the cavity closest to the screw then loosening it a little will help, if it's the further one a little tightening could do it.
if that don't do it, then breaking the corner of the mold with a stone like Dan suggests will.

Before you modify the mold, place a sheet of 220 or finer grit on a perfectly flat surface. Plate glass is good if you have any.
Remove the sprue plate and place it cutter side down on the fine grit paper. Be sure you have some lubricating or cutting oil on the paper.

Now carefully scrub the sprue plate on the paper several times and pick it up. You may find that it is warped and does not touch the flat surface at all points.

.

[Shiloh]

I've scribed the vent lines. That has helped.

Shiloh

[runfiverun]

woaoow.
gotta love this place,6 replies and every one was different, but on track to what the issue could be.

[Hawkeye45]

Thanks gentleman for all the info. I will try each one until the problem is resolved. It is good to have more than one option.