Couple reasons I didn't:brush it on and into the shape to be molded. I generally do this to avoid having voids and bubbles at the surface of the mold.
1 - Mine wouldn't brush, it was just bathroom caulking.
2 - I put it in a plastic tube, and then used a floor jack to press that onto the shaft.
I got my alignment bad, and my wall width poor, so I just threw away about 20% of the edge, but otherwise it turned out great with no voids or bubbles. It copied the milling details from the shaft and the surface finish, so, I presume it's good.
It looks like I can get away without doing an early brushing, or using a vacuum chamber.
For my next iteration, I was thinking, a beer can. Then I can be reasonably confident that it goes back into the same shape.-do some more research on making a mold with an outer support (mother mold or a mold box).
But, plaster inside a square box sounds like a better solution. Problem is that there's not a lot of room around the driveshaft to build a box, it's in a recessed hole.
I kind of like having the play-dough consistency, I was going to make my next one upside down because I'm getting sick of reaching in a narrow gap between the milk crates that support the motor.
That's the biggest advantage of the corn starch dough-like mix I've been using. It doesn't stick. Only a little bit to the bottom of the shaft. I've been using baby powder, silicone brake grease, and penetrating oil (each, not together) during various mold pours. The brake grease seems the best.have you been using mold release? Even silicone will stick to metal and tear when you try to remove it if you don't use mold release.
What's mold release made from?
I independently came up with that method as the next thing I want to try. My PVC is a bit small though, and I don't want to buy an 8' just for an enclosure. Maybe Home Depot's got a nipple or something I can use.The easy thing would be to take 2.5" plumbing PVC pipe about 4-5" long (nice flat cuts on the ends, no angles!) and slice it open one end to the other (this allows you to stick a screwdriver in it and pry it open) then cover the split with duct tape.
I thought about that, but, no. I'm only making one of these, I don't want to put too much effort in.-if, however, you want a wax female of the male axle shaft, you need to make an intermediate casting.
My intermediate will just be a plaster pillar of the driveshaft. I don't mind having to make a new one every time I attempt the Zamak casting.
Thanks for the advice. I'm going to try again tonight or tomorrow.