Wednesday, May 25, 2016

DIY Foam Oven

In times past, I've talked about casting puppets in foam latex. I've shown molds and sculpts, and even puppets that have failed miserably -- But I've never talked much about my actual foam running process.
So here it goes.
Up till now, I've always baked foam in a little twelve by twelve (by twelve) inch convection oven that looks something like this -- minus the pizza, of course.
I got it on sale from a local grocery store for $40, and have used and abused it for the better part of eight years -- it was basically "the little oven that could." 
Now, what it had in economical durability it obviously lacked in size. Thus, I have always struggled to make puppets, and the molds that hold them, small enough to fit that cramped space. I've molded things in pieces, severing head from torso -- I've molded things bent into "S" or "C" shapes, all to cut-down the overall volume of the piece (sometimes to the puppets' detriment). 
So after many years like this, I've finally run out of options. I was forced to either, price-out a new
industrial size oven (which is incredibly expensive) or build one from scratch.
Ladies and gentlemen, I give you, the FOAM OVEN OF DOOM!

It's not quite finished, as I'm sure you can tell -- as it stands now, it's in the "testing" phase. 

TECHNICAL STUFF: I made this from scrap plywood that I found around the house, thus, the overall size of the oven was dictated by the size of the board I used. However, under normal circumstances (that is without shoestring budget constraints) one would want to build their oven as large as possible so as not to impose size restrictions on future molds. 
That being said, I settled for interior dimensions of: 21" x 21" x 21". This will allow for a maximum mold size of one inch under the aforementioned dimensions (yes, "aforementioned dimensions" say that five times real fast).
After the boards were cut and assembled, I lined the inside with half-inch foil insulation that I got from the hardware store -- cost $9 – $11 depending where you get it -- And taped all the corners with foil tape -- $7.98.
The heat source will be a 1,100 watt hot plate -- cost $11.99.

Remember, a foam oven needs to accomplish two primary goals, 1) maintain a low heat setting of 160-180˚F.  and 2) distribute that heat evenly -- so you need a fan.

This was the first fan I bought… it melted on the first test and now I need another one. 
So always remember, cheap plastic fans MELT IN OVENS!!
For the next test, I'm going to reposition the fan away from the heat, instead of sucking it in. Which, if you all can learn from my mistake, more power to you -- what I've learned so far, is that it doesn't seem to matter what direction the fan is faced, if it's blowing left, or right, or down, or even straight across the surface of the hot plate, just so long as the air inside the oven moves around.

And for the last of the technical stuff -- I managed to get my hands on a few old oven racks. It's obvious what those will be used for -- but what I'm finding, is that the distance between the heat source and the mould is going to be a little tight; at about 7 -10 inches above the hot plate. Again, under normal circumstances, you'd probably want something like a foot, maybe a 16 inches, just so the mould isn't under so much direct heat.
Once everything is working, I'll be connecting the fan and hot plate to a power strip so they can be started simultaneously. 

Total (approximate) cost: $50. 
And if you add the $12 for hinges and misc. hardware -- $62.
Of course there were two fans in my case, so that would be: $77.

But as I said at the start, I already had some scrap wood, so that reduced my cost by about $13