Heat Source for a Hobby Type of Vacuum Former

How about an industrial heat gun?

Yes for hobby / prototype use one or more heat guns would be best. Get one (or hair dryer) & check the temp - a multimeters with thermocouple (test up to 1,000°) are available for around $10. For larger jobs an extra pair of hands (4 guns) might be helpful.

Pick up a tossed away, or really cheap propane oven, buy a tank of propane, and yer off to the races. Check craigslist.

Ideally you want top and bottom radiant heat, so I'd use a dual element toaster oven.

The heating is too uneven, and it's impossible to hold an even temp.

Ever see what an industrial vac former uses for heat?

I always figured they used a LynDoor hot air pump.

My vacuum former is 18" x 18" and 12"x12" and 12" x 18"....The idea behind a toaster over is good but the toaster ovens I've seen are too small. Thanks anyway

OK, then buy 2-3 toaster ovens and a cardboard (just kidding) box. You surely can take apart a toaster oven and change it into a heating panel, one for above and one for below.

100/500W halogen lamp or lamps?
Del

I'd buy an inexpensive, electric range during a scratch and dent sale. It has all the controls and insulation you need. (A used oven might have food particles in it you might have trouble getting rid of.) Set it up in your work area and have an electrician run the proper electric cable and outlet for it. Then I'd buy one of those large pizza stones and put it on the bottom rack to act as a temperature stabilizer and to make the heat uniform throughout the oven. I'd buy a good oven thermometer and put it on the stone and use it to verify the temp setting control on the oven.

If you're looking for something more DIY -- There are some YouTube videos you might take a look at, done by people who made their own ovens for vacuum forming.

This makes all kinds of sense, now that we know that this is more than a "hobby" set-up.

I think the pizza stone would be a mistake. Commercial vac from machines have electric resistance heaters, top and bottom to directly heat the material uniformly.

Also, a lot depends on the material being vac formed. ABS is easy. Polycarbonate or Kydex (acrylic/PC alloy) is a lot harder to form.

Thanks for the reply....A used oven will take up more space than I have..It would be a good idea if I were doing more forming than I do but in my case it's not practical. I have checked out various videos on youtube and they show the process and the forming part of the project..They don't show heat sources other than an oven or some setup that that you really can't see clearly. Thanks again.

I'd think some quartz heaters would work for you, but you'll need to design some type of heating chamber or box, too.

You seem to be handy enough to cobble something together, good luck.

If you see something you like on youtube, you may want to try registering and asking them the question of what they are using, in the comment section. Just a thought.

Depending on size of vacuum former you can use one or more quartz tube heat pillars.you can control temp with a simple duty cycle energy regulator.

I am not familiar with guartz tube heat pillers. What are they and how do they work. How would I adapt it to my situation? Thanks

Back if the 1960's and 1970's Mattel may a decent Vacuum Forming toy. You still can find them in garage sales and on Ebay and elsewhere. I have one that works very well for manufacturing clear plastic aircraft scale model canopies and other aircraft parts.

en.wikipedia.org/wiki/Vac-u-form

Also, there is a guy in Kingston NY, across the Hudson River from me, that manufactures and sells vacuum-form machines. They, however, are not cheap! I have one of his machines here, and it does work very well!

http://warmplastic.com/

I dont understand whats wrong with the wifes oven.

Its already wired in - the thermostat works and you certainly wont take up any more space by using it and shorely SHE doesnt use it ALL the time

The oven works great however there is a strong oder as the plastic starts to sag that permiates through the house. That's one of the things that I'm trying to avoid....My wife is good with using the oven....it's me that's the issue.

The vacuum forming machine that I have uses two types of heating elements for different material. One element is just a round resistance coil off of a stove top the other is a heating element from an electric range broiler it only heats one side of the material then you flip over the panel to cover the part to be molded and hit the vacuum to pull the material down to form and wait to cool. I pulled thousands of slot car bodies off this unit before selling it to a friend who could not get it to work and gave it back to me.I did not think it was too hard to work. You just had to pay attention to the material when it started to droop, then flip and hit the switch for the tank vac. The biggest problem with these types of units is the material you try to use. Lexan works real fast some of the other plastics took a little longer to work. But trial and error will give you the work time need for different materials, always remember to keep a screen between the working material and the heating elements or you could end up with quite an interesting flame. That if you try to grab and throw out will grab you and not let loose until it cools down and you get an extreme burn as well as a scar to go with it. Still have my scar to this day almost 30 years, cringe every time I think about it, all in all I had a lot of good fun with it and a lot of kids got a lot of time with good people, and not on the streets learning the things they shouldn't know. A few of them are now teaching their kids to have the same fun we gave them back in the day. Duke.

Would you have the name of the place you got this machine? What are the dimensions of the former? Also, sounds like you may have been an Industrial Arts teacher.

The machine that I have I got from a well known R/C plane modeler by the name of Jack Sheets and where he got it from I am not sure. Parts and pieces look professionally done but other parts look like a 6 year old did it. I added the screen after I bought it after the awakening moment of pain and previous fire. I have seen one unit that a friend of mine uses to this day, to pull bodies for the slot car industry. His is a lot larger AT 4 ft x 4 ft. His uses a slide tray from the heating elements to over the parts to be pulled his elements look to be oven or broiler elements from an electric stove he had to replace one element and went to appliance shop for replacement and had no problem locating it.

Since you have had experience using this gadget do you think this idea will work? I picked up two heating coils from a used Farberware rotissiari grill..I plan on fabricating a sheet metal enclosure for them with an open top where the frames of the plastic can rest on until the plastic starts to sag. My problem may be that I need two power cords to be plugged into two outlets...I hope my circuit breakers don't go off or worse yet, my house burns down. What do you think?

Mine is set up with two switches one for each element, You probably wont need both elements heating at the same time unless you are doing extra thick material or hard plastics. One of my elements is a round coil the other one is a W shaped coil. If you need even heat for a small part in the middle of the form the round element was used, for a larger part the w shaped element was used it was more even heat over the whole surface. I rarely used both elements, only for extremely thick parts that took a lot of heat to make it form, be very careful with thick material as it tends to respond very quickly once it gets hot. Also to set the temp if you are going to pull a lot of the same parts you can use a variable autotransformer / variac, sorry if I spelled it wrong. by varying the voltage to the elements you will get an ability to control the heat by controlling the voltage that the elements see. It is a very dependable heat control as you can set a point on the transformer dial and repeat it at multiple different heat settings as the material changes.

First question.

Have you positive or negative forms?

That's irrelevant when discussing heaters.

Variable temperature heat gun and a cardboard box...

JPool said Heat Gun and if you get one with temperature and air flow control, you can set the temp. spot on for whatever molding or other projects you're doing. A simple, folding box with a bit of insulation... Even a cardboard box with a hole cut in for the heat gun nozzle will work quite well. You'll be amazed at how many other uses, as well, for a variable temp and air flow gun that you'll find.

Heat gun would be my last choice for softening thermoplastic sheets.

Unless you don't worry about quality. Unless the sheet is uniformly heated, you will have problems keeping a consistent cross section during forming.

The heat gun idea I don't think you have thought that one out very well, as the plastic heats up you will cause it to expand the wrong way. Then when you set it to form you have thined out the material to the point of distortion as it cools. It makes it very hard to pull a good part without a lot of losses of material because of the pulled part is too thin in some areas and too thick in other area due to uneven heat. With the air movement in the box you will increase the pressure in the box and you will end up with thick edges and thin centers. Not a very stable construction for a part that you may need to be stable and strong. Duke.

I use a box like you descibed for softening my model clay. I use a cardboard box with a hole in it and a photo flood housing with a 60 watt bulb resting on top of the hole...I need about 300 to 350 to soften the plastic. I don't think the cardboard box will be safe with this temperature. Thanks for your idea.

CR4 - could you offer a new setting - as well as 'flat' or 'nested', could you also offer 'show all comments' vs current default 'show on topic comments only'. Ta.

We're way ahead of you.

1. Edit your profile
2. Under Customize CR4, change the setting for Off-Topic Comments to "I want off-topic comments to appear like any other comment"
3. Click Save Profile Changes

Found this blog. and the pics are from it. There info from the author and additional links for info.

Charles

IR lamps which will heat the plastic instead of the air as an oven does.

I made a machine years ago http://cr4.globalspec.com/blogentry/4772/DIY-Vacuum-Forming-Machine and for the heat source I bought an electric BBQ grill that looked something like this for about $20.

I mounted it upside down with a foil pan to hold more of the heat in and I believe another one to spread the heat. It has been a while so I don't recall the details, but it worked ok.

I built a 48" x 48" vacuum forming press for a theater shop class project in 1982.

The forms were made by carving styrofoam with a hot wire knife, drilling tiny holes for the vacuum, and applying a coat of plaster for a rather useless heat shield.

To heat the plastic, I built an overhead heater using a 4x4 sheet of aluminum skinned on plywood. I figured it would reflect the heat. I mounted ceramic light bulb sockets on 6 inch centers and wired it for 220 by placing pairs of sockets in series (got extra credit for that idea). I added some switches so I could turn on/off rows of lamps so I could vary the amount of heat, and the softness of the plastic in certain areas. The heater sheet sat on four legs that could be adjusted to vary the "drop height".

I used four strings to hold up each corner of the plastic so that it would heat under the lamps. Oh yeah, forgot to mention the 250 watt heat lamps.

To mold, I clipped the sheet to the corner strings, raised the plastic to (really close) the lights and when it started to sag from softening, I slid the mold on the table and fired up the shop vac. Dropping the plastic evenly onto the mold was tricky but it worked.

The entire setup is still in use in the university scene shop.

How many heat lamps did you have to use? How many do you think I would need for an 18"x18" sheet of plastic?

The lamps were on 6" centers starting in the middle and working out. I think there were 8 rows of six. For your 18x18 I think 4 would do it. 8 would be much better as you could increase lamp-lexan distance a little and get much more even coverage.