Weird mould problem

[JustJim]

How's that for a descriptive subject line?

Mould in question is the Ideal 358416 4-cavity I've had listed for a while. I'd previously cast a few hundred bullets with this one, w/o problems. Normally I bottom-pour, and I suspect this may be the issue.

I received a question about the diameter it casts, so this afternoon I heated up the pot and ladle-cast some bullets. I was getting some finning on the bases of the bullets, as if the sprue plate was cupped. After the mould cooled, I checked the sprue plate and top of the mould for flatness using a straight edge. They both seemed flat. I almost wonder if the sprue plate is warping as it gets hot, then straightening out as it cools.

The mould has not had an overly-protected life. Some previous owner used a metal hammer instead of a mould mallet, so the sprue plate is peened on the strike area. Someone (probably the same PO) tapped on the bottom of the mould, inflicting some further damage. I'd cleaned up the blocks and the mould was performing ok until now.

Ideas?

Thanks,
Jim

 

[Ben]

Jim,

If you are ladle casting.
Try this.............:
Hold the ladle about 1" away from the sprue plate and let the lead
free fall into the hole.
Some moulds don't like " pressure casting " where the ladle is in actual contact with the sprue plate. Creates finning on some moulds.

May help ? ?

Ben

 

[JustJim]

Thanks! During the time when I had a custom bullet casting business, I did a lot of ladle-casting, and developed a habit of aiming the pour for the side of the opening in the sprue plate. This seemed to increase consistency in bullet weight. That's probably how I was doing it this time. When I heat the pot up again, I'll give the pour it straight in approach a try.

 

[fiver]

the finning was on all of the bullets?
it was under the sprue plate and not between the blocks?

the where is gonna point you in the right direction, it could be a simple as the pins, or their alignment holes are a bit out causing the top of the mold to stay open a titch and the extra alloy from the ladle is exploiting it.
or someone over vented the top corners... anyway [shrug]

 

[JustJim]

Finning is on the base of 2 of the bullets, under the sprue plate. Picture an Ideal 4-cavity mould on the desk in front of you, sprue plate pivot on the left. From left to right, cavities are #1-#4.

Cavity #3 had finning about 300-315* around the perimeter of the base, with the gap in the fin over the seam between blocks.

Cavity #2 had finning all the way around the perimeter of the base, possibly a bit more pronounced along the seam, closets to cavity #3.

No finning on cavity #1 or #4. And this didn't happen when bottom-pouring. Alloy changed (from WWL to 3# pure lead/1#WWL). PO had coated the whole mould with graphite mould release, which I sprayed off with solvent before the test today. Since there was very little left in the cavities, when I ran a few hundred bullets from the mould earlier I didn't worry about it.

Suppose the mould release was covering some minor warpage on top of the blocks or bottom of the sprue plate? After I do the test Ben suggested, I may try polishing the sprue plate on some 1,200 grit wet-or-dry on plate glass.

 

[CWLONGSHOT]

That kind of damage sound like it might have cast alot if zink in the mold.
Only ways I see finning on end end of a bullet is missalignment or "shade tree adjustment" Larger venting is also aligned with casting in zink.
I would change and fit a new spure plate. Then look real close at venting and allognemnt.

Hope ya can save the mold.

 

[fiver]

the middle 2 would sure indicate some type of plate [or hopefully not block] warpage.
usually it's the front 2 or the back 2 if the plate is too tight or loose.
i'd try another sprue plate.

 

[Ben]

i'd try another sprue plate.

I'll 2nd that ! !
Or put your current one on a surface grinder to insure it is flat.
At this point in time, it doesn't seem that you've got a lot to loose.

Ben

 

[Dimner]

Some previous owner used a metal hammer instead of a mould mallet, so the sprue plate is peened on the strike area. Someone (probably the same PO) tapped on the bottom of the mould, inflicting some further damage.

Sounds like the previous owner was also hitting the bottom with his wonderful metal hammer to get bullets to fall. If that is the case, you may have more than just 1 problem with the mold. After situating the sprue plate, I would check the alignment pins as well as the screws/pins that hold the mold in place to the handles. Handle jaws have a bit of play in the grooves of the mold. Hitting a mold with a metal hammer, repeatedly, may have cause damage to those pins.