Aluminum Maxi Ball mould problem

[zouaveherb]

I tried casting some maxi-balls in a new-to-me aluminum block mould using soft lead. I had issues with mould fill out. I don't have any other experience with aluminum blocks or with just lead. My previous experience has been with steel mould blocks and with alloys that had some tin to help with fill out. My Lyman thermometer showed a temp of 700 degrees and I was using a hot plate to warm the mould block. Anything I should do to help the soft lead get into the nooks and crannies?

[bosterr]

If you're using pure lead in an aluminum mold you're way too cold. You need to be at 800 degrees or hotter.

[jimb16]

It also helps to flux the lead regularly. Don't know why it helps it flow, but it does.

[WheelgunConvert]

If you are using a bottom pour unit, preheat your mould beyond your normal and use a dipper with a higher volume pour. It took me several casting sessions to get it worked out for me.

The good news is if you can only get 20-30 good ones, you are most likely good for a couple range trips.

[Conditor22]

Make sure your mold is 100% clean
+1 on 775 - 800° for pure lead
preheat the mold well. either put it on a hotplate for 420° or hold it closed snugly then dip it in your pot until the lead flows off easily.

on a bottom pour pot, you can "pressure pour" hold the sprue plate hole snug against the pour spout, pour until full then drop the mold (filling the sprue with lead before you stop the flow) this method is good for cold/cool molds,

[zouaveherb]

Thanks! I'll crank up the temp and try the pressure pour procedure.

[Dusty Bannister]

Wear gloves when pressure casting. The lead will spurt when the mold is overfilled, which is normal. It also can spurt the excess in 360 degrees, but more often than not, spurts toward the handle. Not a good thing. You might find that the mold tends to stick to the nozzle so plan to give it a little twist if that occurs and then add a sprue puddle to allow the casting to draw from the puddle while it cools and shrinks. Do this without any delay and you will have few voids or shrinkage issues. If using a bottom pour pot, open the valve fully to fill the mold to avoid those "soft serve ice cream" wrinkles. One percent tin added does little to increase hardness but can improve the alloy flow.

[zouaveherb]

Wear gloves when pressure casting. The lead will spurt when the mold is overfilled, which is normal. It also can spurt the excess in 360 degrees, but more often than not, spurts toward the handle. Not a good thing. You might find that the mold tends to stick to the nozzle so plan to give it a little twist if that occurs and then add a sprue puddle to allow the casting to draw from the puddle while it cools and shrinks. Do this without any delay and you will have few voids or shrinkage issues. If using a bottom pour pot, open the valve fully to fill the mold to avoid those "soft serve ice cream" wrinkles. One percent tin added does little to increase hardness but can improve the alloy flow.

I raised the temp to 800+ and the results were like night and day. I went from 100% defects to about 15%. I noticed that there was a bit of spurt with the pressure pour, but it didn't go very far. Just a little bit towards the handles and down the side of the mould block.

My standard apparel when casting anything is a full face shield, welder's gloves, and a heavy insulated flannel shirt. Some may say that is a little paranoid, but I've heard too many 1st hand stories about the Tinsel Fairy, along with seeing the scars to back the stories up. Also, about 15 years ago, I had one drop of solder hit my hand. Took weeks for it to heal and I can still vaguely make out the burn scar.

[Ozark mike]

I also dip the edge of my mold in the hot lead to heat it up before I start casting