I'm needing to make an impeller/propeller with thin parts. Has anyone tried using the pink foam sawdust and mixing it with a low melt wax to make a slurry, heating it up just to it's melting point,and then injectinng that into a mold? I am going to try it, but would appreciate feedback .
What I am thinking is to make the slurry, warm it up to just the melting point, and inject it into a mold. After it cools, remove the piece from the mold and then cover it with the drywall compound with a drop of Dawn mixed in. Then bury it in sand and pour the molten aluminum into it. More of a lost foam casting with a binder of wax....
Interesting experiment, I have no idea if that's going to work or not but please, take lots of pictures, succeed or fail, we want to see it.
To successfully do so with the lost foam casting method, I'd expect you'd have to have a very low percentage of wax and at that percentage, hard to imagine it would be injectable. Hand packable maybe. The commercial method for making lost foam patterns blows pre-expanded polystyrene beads (not bean bag beads) into an aluminum mold, then introduces steam to further expand and bond the beads, same way packaging preforms are made. It's been discussed and tried here several times but isnt very practical at the hobby level. Best, Kelly
Well that turned out tpo be a compete disaster! I did a lot of things wrong: didn't sift the sand, shook the bucket but did nto use a vibrator, etc. The mixture was at least 30% wax, even though I compressed the foam bits together as much as I could. I did not have a wax injector (got one on order), so I had to compress a layer of foam, then drop wax onto it. It was very tricky to pour the wax into the foam, not being able to regulate the temperature of the wax. Just alittle too hot and it melted the foam, just a little too cool and it was too visccous to fill the voids in the foam. But I think the biggest problem was just too much wax. I had some sprue wax and that probably melts at a higher temperatture than a fillet wax (got soem of that on order also), so when the aluminum was poured into the top of the mold, it was all foam until it hit the cup shape. Then I think the wax did not melt nearlly as fast as the foam, created a damn, and as you can see from the photos, the aluminum filled the spout and created a ring on the top of the sand. Will try again when I get a different wax and a wax injector.
