Vacuum Form Machine Enhacments -Cheaper Heaters Next >>
Building Cheaper Heaters
By Deadline on Apr 06 2012 Category:Vacuum Form
One of the biggest costs to building a Vacuum Form Machine is the Heaters. Right? Well maybe not.
So kits are the simple way to go. As seen in the related article you can just order kits. They come with all the stuff you need. Spend an evening or two drilling holes and forming wire and poof, you have heaters. See Kits Here. For my first 2x2 that's what I did. It was quick, no muss, no fuss and you wire them in. Not cheap mind you.
What if it's not as costly as we think?
When you look at the kits you get to thinking. At a rough cost of $60+ per 6 in x 24 inch panel you start to wonder what if one breaks? Yes, folks they do break, they are like light bulbs. They are good till they're not and then you need new wire.
So wire. Nothing hard here. Simple 20-22ga. NiCrome. You can buy it by the roll and spin it around a 1/4 inch dowel with a drill or buy it pre-wound. Spools are really cheap. Try ebay. Or order it pre-wound here. The key information is getting the right amount on each 6"x24" board. The magic number folks is 42 ohms. For the 220 v systems you need each panel to meter out at 42 ohms. They need to be balanced to heat evenly.
So boards. The suggested material is ceramic fiber board. What is ceramic fiber board and why do we want it? Well it turns out that ceramic fiber board is used as shelves in pottery kilns. It's cool stuff designed to get very hot (up 1500 F), be somewhat easy to cut, used a few times and when to much glaze gets on it, and it is thrown away. Yes, tossed. If you have a pottery firing place near you, you might find it there. If not you might try what I did.
So what else gets fired in a kiln and takes high heat? Well, the ceramic & porcelain, right? What are floor tile made from? Ceramic & porcelain. Now, I can't find any information as to what heat a floor tile is rated for but if it can be fired in a kiln a few times to put glaze on (at 1500 F or so ) then it should work for us. And it does nicely. Cheap 12 in x 24 in white floor tile from your local home supply store is much better than any Hardi-backer.
Cut it with a wet tile saw into 6 in x 24 in (or a little under so it fits nicely in the ceiling grids). Lay out the hole pattern and mark it. Drill very carefully with tile bits and water. Lots of water and very slowly. The bits won't last, so you will need several. Drill the corners first with fresh bits! As you can see in my photos, old bits and corners don't match and you get a break.
One tile makes two boards so you only need 2 or 4 at $2 a sq foot. With the wire, which has been spun, measured, and stretched on the kit frame. Affix with cotter pins "loosely". Bolt the ends down and through to the heavy gauge 220 v wire on the back and light them up. Mine sit side by side with the kit ones and have been going for a year.