Vacuum former: update 4

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Progress at the end of the day

Today I mounted the platen to the vacuum chamber and finished the wiring.

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The platen screwed down to the walls of the vacuum chamber; also shown is the frame bracket for holding the plastic

To attach the platen to the vacuum chamber, I first thought about using J-B Weld. However, I like being able to disassemble a piece of equipment for repairs, so I decided to screw the aluminum plate down to the wooden support. I put a screw in every 4 inches or so and it seems to be holding securely. I'll see whether it's air tight enough when I try to vacuum form something.

I finally got to the wiring today. Everything went together well once I found my soldering setup. I only needed to solder a couple of leads to the fuse holder. Everything else is attached with high temperature twist nuts. 

I wired in the shop vac first, and that worked great. Then I wired the heating elements and discovered that the pilot lamp doesn't work (I probably damaged it when removing it from the toaster oven), and that wiring all the heating elements in series doesn't generate enough heat.

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I rewired so that two heating elements each are wired in series. Then the two pairs of heating elements are wired in parallel to the power switch. That worked much better so that the heating elements warm up very quickly.

With the wiring complete, I have the following items left to do:

• Put a protective set of walls around the oven box. Those are exposed live wires when the power is applied
• Add a latch to the frame bracket
• add spacers to the frame bracket right next to the handle in order to remove some of the slop when moving the frame bracket from the oven to the vacuum
• Add magnetic holds between the oven box and the frame bracket
• Replace the pilot light

Vacuum former: update 3

An unexpected advantage to regularly posting updates is that I review my activities in a more detailed way. And so, when working on yesterday's post, I realized that I had glued the spacers on the wrong side of the platen! I rushed out to confirm my mistake, and sure enough, I had glued onto the working surface. Luckily, it turned out that the adhesive I used was terrible, and so the spacers fell right off.

So today, I cleaned off the glue residue from the platen, made some new spacers, and researched a good adhesive for attaching wood to metal. In the process, I discovered a great site called ThisToThat. You can put in two materials and it will recommend several appropriate adhesives. Between that site and some other prop building forums, the overall consensus was that J-B Weld was the right glue for the job.

J-B Weld for gluing wood to metal

I picked some up today and it is an epoxy. It comes in two tubes, one is labeled Steel and the other is Hardener. It's mixed in equal parts, however the result is much thicker than other epoxy I've used. It makes it harder to spread and so the application took much longer than I anticipated.

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Flattening the platen and applying pressure to the spacers while the epoxy cured.

I use shot for adding weighing to tool handles and playing pieces, and the bag of shot weighs a good 10 to 15 lbs. This is perfect for clamping down the wooden support spacers to the platen.

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The power cord to the shop vac is long, so I cut it in order to wire the vac into the controls and to provide the power cord for the entire vacuum former.

While that cured, I started work on the wiring. I cut the holes for the controls (fuse, pilot light, and 3 position toggle switch) and cut up the power and vacuum cables. I didn't get very far before I discovered some missing tools and decided to call it a night.

So, most of today was spent recovering from yesterday's mistake. I'll get back to working on the wiring in a couple of days.

Vacuum former: update post 2

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Channel mounts are complete with the oven aligned to the vacuum box.

I didn't get quite as far as I'd hoped this evening, but I was able to finish mounting the oven over the vacuum box. Now you can see the basic structure of the vacuum former. What's missing is the bracket that holds the sheets of thermal plastics. The bracket slides along the channels between the oven at the top and the vacuum at the bottom.

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Showing all 609 holes in the aluminum platen along with spacers that have been glued into position.

I also finished drilling the holes in the aluminum platen. In the picture you can also see that I've glued down supports that will keep the platen from sagging in the open area away from the support walls. I used a construction adhesive that's suppose to be good on metals and wood, so we'll see how it looks tomorrow. If the glue is solid, then  I'll use that same adhesive to mount the platen to the walls of the vacuum chamber.

I didn't get the chance to start work on the wiring, so that will have to wait until tomorrow. Also tomorrow, I'll mount the platen to the vacuum chamber and test the overall vacuum system.