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faithblinded · Posted: Tue May 01, 2007 10:42 pm Post subject: 4ft Square: It Will Be Done!

Hey guys,
So I'm going to build a vacuum former. It will be 48" square. Over Under.

my current thinking about pump selection:
I'm currently shopping for a 1hp plus pump. I've found alot of surplus scientific/military grade pumps are on the market at very fair prices. Many of these pumps are completely rebuildable with kits still available. They are often far superior to the ac type units alot of guys are using, except where portability is concerned. Once I get my pump and see how it works out, I'll be happy to assist others in their quest(I have a knack for finding the hidden deals). The pumps I've been checking out were all under 200 bucks and over 8cfm, with some over 15cfm. You just have to hunt the deals out. Of course, if your platen is small, you don't need that much vacuum.
The pump is the first part I intend to buy. Likely the most expensive too.

oven thoughts:
Oh boy, and you thought the last section was long winded... Get ready!
Clearly I will need 220 to heat up a 48" square of plastic.
That's not a problem. I wired a new 50 amp feed to my garage last year, and have space in the box for a 20 or 30 amp breaker. If I go 30 amp, I'll have to disable the compressor or risk flipping the garage main breaker. No biggie really.
My line voltage runs a steady, hot 247 volts; so roughly, if I go with a 20A circuit, I can run a 4500-5000W oven, or if I go with a 30A circuit, I can run a 7000W oven.
I'm leaning towards the versatility of 7000W, but damn, a 7 kilowatt oven is a major draw on the electric bill.
So to overcome cost issues, I'm going to design my own multi layered, zoned Nichrome layout so I only use 7000W when it's needed. A 28" square section in the center will be independently controlled for use with a 24" platen and plastic holding frame. That will save more money when I need to do just a few small parts.
I'm actually looking forward to this and the corresponding control panel design. I believe it will present the most challenge, to get it working well enough to make money with the machine.
Those ceramic standoffs and donuts are driving me nuts. They are way overpriced, and I can't find them anywhere else. And I have a list of electronics suppliers a mile long. No luck. I'd love to hear of another, less expensive source of them!

Darn that's enough for one post!

faithblinded · Posted: Tue May 01, 2007 11:04 pm Post subject:

vacuum chamber:
all my research concludes: don't argue with what works and is time tested, no matter how strange it seems.
I will be using a hot water tank, whatever I can find for free. I plan to add a second tank as soon as I can find another free one.

chassis thoughts:
No lumber here. I'm going all steel, for longevity and repeatability. Most likely will be 1/8th wall steel tubing. Pump will be separate from main machine, by tank/s.
The oven will be up high and stationary. The platen will also be stationary, at a comfortable working height for me. I'm thinking single hole to begin with, but this is one area I plan to experiment with. I'll also build at least one smaller platen for small pulls and plastic. The small platen will fit into the larger one via a flange.
I've given alot of thought to my raising and lowering mechanism for the plastic frame. I'm still undecided as far is this goes. Need to simmer on this one more. This and the oven have consumed most of my thinking hat time so far.

That's all I can spit out for now. I'd like to thank Harley Guy for his project which I'll be taking some inspiration from, as well as all the other great sage plastic masters at TK560.

BTW, none of my uses for this machine are Star Wars related, but the more I look at the forum the more I want to do some Trooping. I was also thinking it would be wicked to make a set of molds for a full size Dalek! I digress...

drcrash · Posted: Wed May 02, 2007 12:01 am Post subject:

Welcome!

I'd be interested in hearing more.

With a 4-foot machine, you could put the tanks under the platen.

Why 4 x 4? What are you planning to make?

(I'm not a big fan of square platens in general, but when you get up to that range, there aren't a lot of options that go evenly into 4 x 8 sheets.)
_________________
Paul (a.k.a. Dr. Crash)

Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com

faithblinded · Posted: Wed May 02, 2007 12:56 am Post subject:

Hey Paul!
I have a list of money making ideas to use a vac former for, but the one that wants a 4x4 table is hydroponic system components. I should be able to make nice 3x3 ebb&flow trays, in addition to items as simple as invincible abs grow pots, 30 at a time.
I have a tendency to overbuild things. I like it that way. As you mentioned, a 4x4 machine should leave zero scrap, which I also like. I don't have much need for the big bed for anything else besides the big hydro trays. But I know if I have it, I will come up with endless uses for the ability to pull 4x4 sheets of thick abs(my goal).
For reference the 3'x3' ebb&flow trays retail for 65-125 ea. bucks depending on the brand/options,etc. They are all Vac Molded.

Another use for the machine relates to another of my hobbies: vintage Japanese motorcycles. The ability to reproduce vintage side covers, and make custom fairings would be awesome.

My day job is as a dealer of vintage goods(furniture housewares clothing etc) in a shop in Cleveland( www.flowerchildretro.com ). I come into contact with alot of unique stuff that needs repaired, which vacuum forming might be ideal for. i.e. plastic dome lamp shades from plastic colored lamps, almost always cracked;tons of acrylic/lucite/plexiglass furniture, knick knacks etc;and other stuff not coming to mind right now. I just see having the big table being helpful in a number of diff endeavors for me. Everything was made from plastic in the 70s!

Good thought about the tanks. Hadn't occurred to me. the scale of this thing doesn't always register in my head,lol. Another big rearrange of my garage is on the horizon.

drcrash

jegner · Posted: Wed May 02, 2007 9:14 am Post subject:

Be sure to run your size through the oven calculator here:

http://www.imperial-armor.com/ovencalculations.html

Sounds like you have a plan. Thurston James suggests a GAST model 1065 pump. So that might be a good starting point for your research.

Keep us posted. Yours would be the first 4-foot-square machine built!

Jim

cod · Posted: Wed May 02, 2007 12:06 pm Post subject:

maybe natural gas would be cheaper than electric at the 4x4 size ? dunno.
_________________
<.o'>

crashmann · Guru Joined: 27 Sep 2005 Posts: 501

Ooh, a 4x4 oven, very nice! I'm also planning on building on of these in my garage, so I am very interested in what you come up with. My garage is wired with 4x 20 amp circuits, and a 50 amp circuit dedicated to the oven. No, our cars will never see the inside of the garage Wink

I'm planning on re-using the 50 gallon water heater tank with the Gast 1065 pump. Thank goodness I used the quick disconnect fittings on my lines. I haven't decided what style platen I will go with - either a single hole or multi-hole like a TJ. I might build both, then figure out a way to swap them out.

The oven will be mounted over the platen and powered by nichrome wiring. I'll probably splurge and go with a boatload of ceramic donuts held to the Hardibacker with copper U-Turn wires. I might also put a layer of thin aluminum on the mounting board to reflect the IR down towards the plastic. Then do the same for the walls (Hardibacker outside, aluminum sheet on the inside).

Ideally, all of the framing will be welded steel tubing. A friend of mine started welding as a hobby, so we'll see about sharpening his skills on my project.

I like the Doctor's idea of using a rectifier to cut down the power output from the oven. But I'm wondering if the plastic drooping away from the oven will cool enough to eliminate the need for power control switches... Only one way to find out - try it and see!

Again, welcome to the board, and I'll be following your project with vested interest!

Charlie
TI-386

faithblinded · Posted: Tue May 29, 2007 11:26 am Post subject:

I have returned from my vacation in California, and can now begin buying parts. Of course I spent more than I wanted to on vacation and must now be frugal for a bit. So I'll probably buy my vac pump last.

I ordered nichrome today, and will be working on my oven layout with craft paper until it arrives. I plan on departing from the standard pattern alot of folks use. We'll see if that ends up being a good idea.

I found a free water heater tank but it had a pinhole or three. I may just go buy one. I'll worry about this more when I buy a pump.

While I was away on holiday, I worked on many sketches for bucks and neg. molds for various items I want to form, and will likely start creating them in my spare time. I want to have a number of them ready by the time I finish my machine.
On this note, can anyone recommend any other(not TJ's) good books on the subject of mold making?

That's all for now, just wanted to post something, since it's been killing me saving for vacation instead of spending money on this project. Now obsession can resume!!!

More to come as the fun starts, and I promise to photograph anything exciting!

Ken in Cleveland