Sticking mould blocks

[S Mac]

My latest mould is an Ideal 454424. Super nice but it requires more effort than usual to open while casting. At first I thought the alignment pins needed to be tapped in a bit, but now after a bit of tapping with no resolution I think maybe it's something else. I did break the top edge of the blocks with a file, like Ben recommends to help the base fill out. Need to give that a touch more, a secondary problem. My point is the blocks stick if I pour a little longer to get the fill desired. When I don't keep the sprue molten long enough to completely fill the base, the blocks don't stick. They are sticking at the top. Any ideas?

 

[RicinYakima]

I would look for a burr on the base band near the parting line. You will need a magnifier, but if making a full base band, that is a likely cause. HTH, Ric

 

[fiver]

yep something with the mold block is holding the halves together.
really really look your bullets over.
a slight off shift, or under roll on the base band would kind of lock things up.
a soft not set up alloy will tear and let the mold open easy a hardened set up alloy will fight harder.

 

[Ian]

Toothpaste time.

 

[S Mac]

Using my 50/50 alloy. There was minor burrs, ran a knife around a bit. Have yet to test. I guess polishing with toothpaste would be a good option. I hate to enlarge the mould, it's plenty large enough now.

 

[Rick]

If toothpaste would remove metal and enlarge the cavity just think what it would do to the enamel on your teeth.

 

[S Mac]

If toothpaste would remove metal and enlarge the cavity just think what it would do to the enamel on your teeth.

I know toothpaste would be a polish only, I have some lapping compound for the ones that cast small. Wouldn't want to brush my teeth with that, they have had a hard enough life already.

 

[S Mac]

I think you guys nailed it, my knife trick helped but probably need to polish it also, still sticks a bit.

 

[Gary]

Toothpaste WILL polish your teeth, at least that's what it says on the tube I have.

If toothpaste would remove metal and enlarge the cavity just think what it would do to the enamel on your teeth.

 

[Rick]

Gary, do you see a difference in polishing and removing metal? He was concerned with enlarging the cavities, if toothpaste could do that you would shortly have no enamel on your teeth. But hey, that pesky plaque wouldn't be a problem huh?

 

[S Mac]

I found a q tip and could feel the burrs, will test again later. Bound to help. Now I need to go polish my teeth.