www.TK560.com

[RRK4]

So that I will stop mucking up everyone else's topics I figured I would make one for my project.

The reason that I first looked into vacuum form machines is to make cheaper mother molds for my silicone glove molds. I make little statuettes, bookends, etc. out of lightweight concrete. Currently I use about $12 worth of Apoxie Sculpt for my mother molds so I am investigating other techniques to reduce that cost without having to use fiber glass.

The basic idea was small tank low cfm pump and maybe not being able to run everything at once on the same circuit. I've got it set up and pulled 25" on the tank with the harbor freight compressed air pump thing. It held vacuum but I haven't gotten this Thomas pump I ordered working yet.

Oven
Like most newbs I didn't want to build an oven the right way so my first purchase was a table top grill at the thrift store. Then I used grill surround to determine the size of my machine.
$8 Salvation Army

Framing
I used aluminum L bars as support from the oven down to the frame for the platen.
$7x2=$14 Lowes

Platen
I built a single whole platen with scrap Corian and recessed a 2" shower drain so that the grill is level with the platen surface. I know this is huge. I was thinking I wanted the same size as the shop vac fitting. Based on the size of the grill the platen ended up being an itty bitty 9" x 14".
Free. My Dad used to be a Corian installer.

Plastic Carrier
I built the plastic carrier out of an aluminum window screen frame and the original frame from the grill, held together with those big black metal paper clips. They ride on the L bars with Corian glides. Right now other then the pump I am most concerned with the metal carrier and what types of clamping strength I will need.
$6.50 Lowes. Also got screen for single hole platen.

Vacuum Tank
I converted a propane tank for my vacuum tank. For some reason I thought the hole in the tank was 1" when I was at the hardware store so thats why I go from 3/4" to 1". Converting the tank was not as hard as I anticipated. To get the original fitting off I put a monkey wrench on it and whacked the wrench a few times with a dead blow hammer. Then I cleaned it out with acetone a few times to cut down the smell.
Curtesy of the previous owners of our house. Free.

Vacuum Pump
When I started building I didn't think I would ever actually buy a proper vacuum pump So I decided to try the $15 Harbor Freight pump that runs off of your Air compressor. It actually worked fairly well IMO. Took about 4 cycles to get down to 25" but with a little compressor my cycles were quick it only took about 5 minutes total. I did end up ordering a Thomas vacuum pump on eBay. Good working order, 30-day refund, $38 shipped. Well, it only pulled about 15" of vacuum and required a rebuild. The eBay vendor refunded my cash and let me keep it so at this point I have rebuilt the pump with new gaskets, reeds, and cylinder cups. However its been a chore to rebuild because the cylinder heads were held on with cemented in brass bolts which I had to drill out. I still haven't gotten it running well yet. Now that the cylinder cups are snug it doesn't want to turn over. I know I need a new capacitor but I hope that is the only problem.
$9.50 + $10.76= $20.26 Rebuild kit from OilFreeCP

Plumbing
This is a diagram of my plumbing that I made by cutting and pasting crash's diagram from another thread. I think I will hold off photos until I make a successful pull. That way at least I will have functionality to support my naive design.
+-$35 Lowes


Oh and I went to art school so criticize away. I can take it.

[RRK4]

I may need to glue in a constrictor if the huge whole in the platen ends up being a problem.

I am currently mounting some catches to hold the carrier frame up to the oven and one to hold it down to the platen.

Still unsure about the plastic carrier. Didn't find a whole lot of info on here about this part.

[jdougn]

Good diagram but I would suggest two changes.

Ditch the shop vac. The shop vac will only provide a few initial inHg of vacuum. My system pulls 3/16" ABS with a vac pump and the tank. Look at the Belovac vac formers and any other commercial vac formers I've seen and none use anything like a shop vac.

Move the platen between the tank and the vac pump. With the platen between the tank and vac pump you can isolate the tank after the initial pull if needed. On the large & deep pulls the tank will get "polluted" by the intial pull. But the tank can be isolated and shut off from the platen and pump. The final pull is done using the rapidly increase vacuum straight from the pump since it does not have to pump down the tank also.

my .o2,
DougN
_________________
DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions.

[RRK4]

Hey, thanks for the response. I will do exactly what you have said if I ever get this pump running well. I made it this way because I thought I was going to have to use the harbor freight pump powered by my air compressor and I would want to get as much air as I can from under the plastic before I open the tank because it was going to work as the hard pull. Kinda backward from the standard process to get a deeper pull then a shop vac alone.

Any idea if the two inch hole in the platen will be dysfunctional?

Also, how strong does the plastic carrier need to grip the plastic?

Edit
Actually I was thinking about it and if I just add another ball valve above my tank wouldn't my current plumbing still be able to work?

Like this.

[jdougn]

As long as the tank can be isolated from the pump/platen it'll work. You want the plumbing to be as simple and straightforward as reasonable so plan that out carefully. The fewer elbows, tees, and valves in the line the better the vacuum will flow and the cheaper the plumbing system will be. The 2" hole is much bigger than needed so it should function well. My 2'x4' system uses a 1" hole and does fine with vacuum flow.

Strength of the plastic carrier frame is a function of the type of plastic used. For example, 3/16" ABS will need much more holding power than .060" HIPS. Follow some of the examples in builds on TK560 and you'll get a good start. The better systems usually use toggle clamps around the perimeter.
hth, DougN
_________________
DougN - Just in case you're wondering, I got my "rating" legitimately... by posting aimless drivel, useless advice, and pointless questions.

[RRK4]

As far as the plumbing, if you take away the gauge, check valve and the relief valve since they are necessary tools, you get a two valve, two T system. I don't see how you could eliminate anything for a two stage system.

The 2" platen hole worried me because I was wondering if you could have too big of a hole.

I have looked through the gallery but are there any specific builds that you remember giving good info on the plastic carrier?

[RRK4]

Hurray! I finally got my pump working. New capacitor, seals, gaskets, cylinder cups and liners. The biggest pain was that the piston heads were held on with brass bolts that were cemented in place so I had to deal with drilling them out etc. but its over now!

I pulled 25" on my tank before it really slowed down. I was a little afraid to let it chug away at those last few inches since I just got it working. Do you usually try to get you tank as low as possible for every type of plastic?

[IMMark]

Congrats!
Glad to hear you got it up and running.
I had read (somewhere on here) that you don't need a high vac number on the tank in a 2 stage system, like around 20 is plenty. You use that at first, then switch to the pump to get max vac draw.
I have only used .060 HIPS, and I have used 15 or less and it draws it right down. Perhaps more depending on other plastics?
I was using pump only at first, and must say I love the 2 stage system...big difference!
Mark