16"x48" oven watts needed

[thumper650]

Hello starting to build a Vacuum former. 16x48 is the oven size. It will be an over under because of length. I will be forming .062 ABS haircell only in it. Im wanting to go with quatrz rods maybe 2 to 3. There length is 46" the heat part is 42". My mould will be 36" long, 10" wide and 4" high. The watts available are 500 to 3000. I have 220 avail and would rather use it. The rods seem more durable than the wire setup. thanks for any advise I can get. Im waiting on my membership on tk560 to be ok'ed.

[jdougn]

I am just getting done building a 24x48 over/under. It would've been much easier, faster, and probably cheaper if I had just bought the Proto-type plans in the first place. They have the oven kits already available to work properly and have sourced the parts you'll need. At least check them out at Build-Stuff.
Build-Stuff.com
Good luck on your project and have fun with it!
dn

[drcrash]

Hello starting to build a Vacuum former. 16x48 is the oven size. It will be an over under because of length.

I'm not sure what the length has to do with over-and-underness, unless you're just saying that it's big enough you want the compactness of an over-and-under arrangement. A side-by-side arrangement with a flip frame would work if you flip plastic over the short way.

I will be forming .062 ABS haircell only in it. Im wanting to go with quatrz rods maybe 2 to 3. There length is 46" the heat part is 42". My mould will be 36" long, 10" wide and 4" high. The watts available are 500 to 3000. I have 220 avail and would rather use it. The rods seem more durable than the wire setup. thanks for any advise I can get. Im waiting on my membership on tk560 to be ok'ed.

Can I ask what you're making, and how many of them you're planning to make? What's your budget? If you're not going to be using the machine a whole heck of a lot for a long time, nichrome may be plenty good.

I'm not sure why you want quartz, specifically, or those tube lengths.

I think 42" is an awkward dimension for a straight rod heater for your application. For molds up to 36" long, you probably want a few more inches of plastic length. (Maybe 4" on each end, for a total of 44", if your molds are 4" high and steep ended, but maybe less if your molds are rounded or sloped gradually down to the ends.)

For a plastic length of 44", you probably might as well go with 48" because 44 doesn't divide neatly into a standard sheet dimension.

Given a length of 44 or 48, you want a few more inches of heated oven width to avoid cold edges---that is, the heated part of a straight rod should extend several inches past the plastic----so maybe 50 or 55 inches.

If you want to use straight rods, it seems likely that using shorter rods the other way would work out better.

For the other dimension, you might go with 16" wide plastic and roughly 22 or 24 inch (heated length).

Then again, if you ever want to sell the machine or use it for other projects, you might want to go for a more standard size, like 24 x 48, which would be more generally useful. (16 x 48 is a very long skinny aspect ratio, which is fine if you only ever want do do long skinny things with it, but it might be worth making the machine useful for not-so-skinny things.)

If you want to go really cheap, consider a nichrome oven flip-frame type arrangement a la Thurston James. If you want something nicer, and have a bit more money and/or tools and skills, consider Doug Walsh's Proto Form plans. (2 x 4 feet is one of the options.)

If you like designing things yourself, you can mix and match features, like making an aluminum oven with nichrome coils and putting it in an over-and-under arrangement like Doug's.

One nice thing about Doug's oven design is that his (calrod) bars have turned-up heated ends. That puts out a bit more heat near the edges, without needing the oven to be as wide as with simple straight bars. With straight bars, you'd have that heated part plus the cold ends and connections adding to the width of the oven.