- #1
tiviny
- 21
- 0
I am trying to make a mold of a deep parabola, by putting plaster of paris in a spinning flower pot. I've got another thread going as well. So far I've tried using and making all sorts of spinning bases, however inconsistencies in the rotation of the pot have to be almost invisible for the plaster to set correctly. This is surprisingly(!) hard to do, I'm hoping hanging the pot from a motor will help with this.
My question is more about the substrates. I want a positive mold, so the plan is to cast the plaster, then form a fibreglass mold. But, the plaster of paris ineviatably contains bubbles, and these bubbles all migrate to the lowest point, right where the most accuracy needs to be. This is a big problem, and I'm trying to think of other materials to use, I was thinking liquid rubber or foam of some sort? I could perhaps use the plaster as filler, and do I final thin coat of epoxy resin, but I don't even know how the epoxy will perform.
The ultimate test is water. I've got close but it is very hard to get water to hold itself motionless as a (very deep) parabola. A good trick is to glad wrap the top, so the air inside spins up to speed as well. I'm working on the smooth rotation, should be just a few more days, but in the meantime can anyone else thinkk of a good setting liquid to use?
cheers all, tom
My question is more about the substrates. I want a positive mold, so the plan is to cast the plaster, then form a fibreglass mold. But, the plaster of paris ineviatably contains bubbles, and these bubbles all migrate to the lowest point, right where the most accuracy needs to be. This is a big problem, and I'm trying to think of other materials to use, I was thinking liquid rubber or foam of some sort? I could perhaps use the plaster as filler, and do I final thin coat of epoxy resin, but I don't even know how the epoxy will perform.
The ultimate test is water. I've got close but it is very hard to get water to hold itself motionless as a (very deep) parabola. A good trick is to glad wrap the top, so the air inside spins up to speed as well. I'm working on the smooth rotation, should be just a few more days, but in the meantime can anyone else thinkk of a good setting liquid to use?
cheers all, tom