Homebuilt Vacu Mold Questions

[Nor Cal Mike]

It looks like I can get a two burner electric hot plate delivered for about $30 bucks. But I am going to look around the junk stores around here firse. I used to have a little electric Bbq that someone gave me. I haven't seen it for a long time but it might still be around here. I should be able to come up with everything else in house.

[munter]

My setup is low low tech.

I use a 2000watt household vacuum cleaner for suction and a single burner electric hot plate for heat.
I wont mention the transparent sheet holder but my box is nicely done with a perforated metal plate on the top.
Most important thing is it works and can be put away easily and quickly.

[Kemtronracer]

[chappy]

Mike if you are goingmto heat from the top, you do need to be closer to the heat source as Kemtron states.
If however you end up using a single or double burner hot plate below , mine is set at 9 inches, as the surround of foil on the heat box reflects the heat up and stays in the chamber.
You may have noticed on the small one , which is actually a dental one for making tooth guards and whitening plates, it heats from the top also is is much closer.
Looking forward to seeing what comes from the laboratory of Dr NorCalstein lol
Bob

[Nor Cal Mike]

Can I heat up enough plastic to make a single 1/24 slot car body with a single burner? I can't imagine ever making anything larger. I am going to try the flip over sheet holder with the burner facing up in a box lined with foil.

[chappy]

Yes you sure can, but you will have to make sure you have a large enough plastic sheet so it gives complete coverage without too much thinning.
Basically you want the sheet be soft enough to go over the buck, plus a slightly raised pedestal that is wider at the bottom for easier removal.
If you use 30 th PETG for a good durable shell, you want about 1.5 to 1.75 inches of sag in the middle of the plastic.
if the buck plus pedestal measures 3.5 inches by 8 inches ,, I would want a plastic sheet of about
5 inches by 10 inches.
Best to have enough to start. You can always downsize after some tests , or upsize if required.
Hence my 10 x 10 table.
Mike I should add that on larger molds I prefer to come down on the buck rather than swing over
simply to avoid the sag from catching itself.

Bob C

[Nor Cal Mike]

Great information Bob. Thank you very much.

[Nor Cal Mike]

I was digging around in my junk shed and came up with a small, rectangular Weber gas Bbq that hadn't been thrown into the recycling yet. I thought it might make a good oven for my vacu set up. Current thought is to start out, I would have the oven separate from the vacu box and I would move the framed plastic from the oven to the vac box manually. I originally thought that I would mount my hot plate into the old Bbq after removing the gas burner guts. But then I thought the gas burner still works and that maybe it could be utilized for the heat source. Anyone have any thoughts on the matter? There really much difference in effort on my part to go either way, gas or electric.

Thanks,

[chappy]

Hi Mike, I havent seen it done with open flame before.
I have seen the old electric BBQs, but not gas.
I suspect the usual hazards of heat control and plastic with open flame.
But I've never tried it.
Bob

[munter]

I use an electric hot plate and move the plastic manually to the vac box.
If you had a steel plate to sit over the flame and then lower the plastic over that??

[Nor Cal Mike]

Ya the steel plate would be mandatory I think. But otherwise it should work. The flame could be adjusted as well as the electric hot plate I would think. I will probably go with the hot plate since I already bought it. When I found the old gas Bbq I just thought, "what if?" And I am a guy who is always going outside of the box LOL.

[btaylor]

The fumes from the unburnt gas will taint your clear plastic. No flame ever burns 100% clean,and there are agents added so you can smell the gas as well.

Edit: I should have mentioned that i had tried the open flame thing, thats how i know it will leave what seams like oil spots on the clear. I use PVC plastic, so your results may vary. It did not do this with electric heating, so i figured it was impurities in the gas flame. Not scientific, but there was a big difference,

Bob

[dreinecke]