Vacuum Former 2





Introduction: Vacuum Former 2

About: I enjoy building things more than actually using them.

This is the redesign of the vacuum forming machine I built this past summer. Here my first design Vacuum Former and if you look at the last step you can see why I redesigned it. If you don't know what a vacuum former is check out the links on the first step of my other instructable. I'm not going to go over everything again but you can use my other instructions to build the oven, platen, and frame. Only minor changes where made to these parts and a different base was made.

First I think I should go over why my old machine didn't work and why the new machine works a whole lot better. With my other design the plastic was heated while sitting above the oven, I did this because heat raises and I thought this would heat the plastic more effectively. As you see I underestimated how effectively this method actually heats the plastic. The plastic got to hot, sagged to much, touched the coils and caught on fire. The new design holds the plastic below the oven so that when it sags it falls away from the coils. It might not heat the plastic as fast but the heating process is much more controllable.

Step 1: The New Base

The new base was made to hold the oven upside down, hold the platen directly below the frame and hold the frame in place while the plastic sheet is being heated. The base was made from standard lumber you can get from Lowes or Home Depot. I nailed it together with a nail gun but screws could be used too. It also has some small angle brackets and hex bolts. Here is a list of everything you'll need.

Materials needed for the Base:
Qty Item
1 1x4x8ft lumber
2 1x2x8ft lumber
4 1in angle brackets
4 5/16in-18 x1.5in hex bolts
4 1in wood screws (for the angle brackets)

The pdf has drawings for the oven and the new base. The base parts are VF-09 to
VF-14. There is also an assembly drawing of the base with all the parts labeled. The angle brackets were drilled and tapped to 5/16-18 threads for the hex bolts. This is so you can clamp frame to the oven while the plastic is being heated. To take the frame out once the plastic is heated you have to loosen the 4 bolts pull the frame forward and off the bolts and then just lower it onto the platen.

Step 2: Changes to the Frame, Platen and Oven

Starting with the oven, I added extensions to the short ends so that they would fit it the new base. This is because I wanted to be able to take the oven off when moving the machine. The oven is heavy and makes the whole thing a little top heavy and being able to take it off makes it a lot easier. I added four short extensions to the bottom side of the frame. These parts sit on the bolts on the base. I added some of the same balsa wood that I used to separate the layers of the platen to the bottom of it. The platen sits on the risers on the lower part of the base and the balsa wood pieces locate the platen on the base.
With this design I made the oven and the platen removable because these are the things I might make changes to in to future. So if I ever want to redo the platen, maybe with an aluminum surface, I'll I'd have to do is take the old one off and build the new one to fit in the same manner on the base. This makes upgrades very easy.

Step 3: Test Run 2

I cleaned up and tested the oven and put everything together for another test. This time I had a fire extinguisher ready just in case. The plastic took about five minutes to heat up and sag about 1.5in. The oven smoked a little because of the soot and ash still in it but I think that will eventually burn off. I put some left over pieces of wood on the platen to make a tray organizer for a desk or tool box drawer.
The plastic formed pretty well but it could be better. I think I need to let it sag a little more. On one side it pulled out of the frame so I'll have to put some spacers on the frame to clamp the plastic tighter. I also need to experiment with different shapes to figure out how to avoid the webbing that happened at the corners. The shop vac worked pretty well but this could be upgraded too. Overall this is a good start though. I want to make some body parts for my motorcycle and I have a few other ideas. I hope this was enough info for you to make your own vacuum forming machine and if you have any questions just post and I see if I can help out.



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    25 Discussions

    One way to reduce chance of webbing is to place small wood blocks an inch or so away from the corners that are webbing. The blocks will basically serve to pull the hot plastic evenly away from itself at the corners.

    I can't quite figure out how you get the heated sheet in the frame from the oven to the platen. With the previous version it was straightforward - the frame was meant to flip-flop from one to the other. With this one - does it slide down the inner construction to the platen?

    Well done for overcoming the heat/sag issue. Great engineering. :)

    This is a really great design. I was wondering if I could use a couple of commercially available hot plates, bolted upside down into the upper box, instead of messing around with building my own heating elements?

    Although not a complete success, you did show a lot of ingenuity with your heater box! Not only is your box insulated, the cement good heat retention to some degree as well. Thank you for taking the time to share it. Can you please post a video of Version 2? BTW, more holes will help on the vaccum bed. Also, you may see, sometimes vaccum formers draw the material with a male form, or air pressure, FIRST, before final form. That can help with 'webbing' on corners.

    O.k. everything seems good, but... what's about the air-aspiring pump? I think that an usual household vacuum-cleaner isn't enough... Please, let me know where to find a vacuum pump, efficient, reliable and cheap!

    1 reply

    I started building a vauum former but I used perf board for the platten which has holes about every 1/2 in (I'm guessing, I'm not with the pice right now). I havent finished my oven yet but my guess would be if you had used the perf board (That stuff you hang tools on with hooks) you might be able to avoid the webbing since it has a vacuum source closer to every piece of the parts that you are duplicating, along with letting the plastic sag a bit more. This is just a theory at this point since my device isn't finished yet but it makes sense to me.

    So it is still NOT working correctly.

    It would be great if you could annotate your photos a little bit. As far as the framing is concerned, have you considered grid beams? I have found them enormously useful in speeding prototype frames/structures.

    I have landed a picture wall heater, which is basically the same as your upper section but comes pre made.
    My hope is to find one more of these and make a 30 x 60 inch vaccum former. This way I can only fire up half of it when I dont need the full size, or both when I do.
    Is there anything I should know electrically about these before I start hacking and cutting my wood stock pile up?

    2 replies

    I don't have any experience with a wall heater, but it sounds like some thing I could use.  Its basically a resistance heater like the coils I used right?  It sounds like it would be well suited for a larger former. 

    As far as electrical stuff goes, I wouldn't touch it.  Just mount it to your former and plug it in. I'd like to what you come up with some post an instructable or at least some pictures.

    Its about 26 by 38 inches. I was planning to just remove the painted skin or face, to expose the inner coils.
    Im hoping to land two of them, so I can combine my CNC router projects with the vacuum former. I plan on making some custom car body parts.

    Oven: I am making something similar but more compact. Oven is about 380 x 380mm and four Quartz heaters each 415W. Will use 20A diode to reduce heat if needed. Instead of concrete board I am using FIBEROCK. It is light, fireproof, quite solid and can be easily cut with utility knife. Board was $13CAN. I've tested board with butane torch. Eventually it would kind of burn but only at the edges and when torch was very close. Oven will have Al underlining and U-shaped reflectors to help distribute heat. I will also use thermostat since I've salvaged (new) B&D; oven. It was under $50 and buying heaters on internet would cost more. Heaters have some kind of metal shields on top of them. They have some (smartly designed) holes that let heat more at the end of the heater than in the center. Comment: I think that vacuum table needs to have better surface than unfinished plywood. That would help creating better seal.

    whats a good site to get polystyrene? and are there any substitutes? I need a few 12" X 12" sheets. hopefully cheap

    Good improvements from the original design. Part of you problem with the webbing comes from the sharp squared off angles of the pieces. The way around this to either make the sides shorter or lessen the angles. Or if thats not possible, use some gloves (heavy leather) and press down slightly at the corners prior to and slightly during the vacuuming stage. Don't press down too hard or you'll leave indentations or glove prints. The pressing also helps in certain spots that might be slightly recessed.

    2 replies

    I knew the pieces of wood probably would not mold to well but this was just a test run. I plan on making a mold of a seat for my motorcycle, which should work better.