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+--- Thread: Thermo forming madness (/showthread.php?tid=1199)
Thermo forming madness - JB3 - 03-08-2010
So in this thread- http://www.superturbodiesel.com/std/vacuum-form-headlight-doors-t-879.html, I made a couple of weird headlight panels using vacuum/thermo forming of plastic polystyrene sheeting. Aside from the crudeness of the mold and process, the parts turned out decently enough for me to continue and make a better version.
That 2x4 and plywood machine sucked big time, and was a little small, so here are a few pics of my NEW machine, not totally complete, but you get the idea!
This machine is made almost exclusively out of garbage from a scrap yard, and crap lying around my house, so forgive the crudeness. Ingredients include- an old computer mainframe tower, metal shelving, patio door hardware and rollers, dodge caravan rotors, a snow shovel, garage door parts, an old oven, and random metal scraps.
To finish this machine, I need to mount the heating elements, and the table which are next. Im still gonna use the principle of using the wet dry vac for suction, but this thing should eliminate most of the transfer PITA and move it all into one big motion, and Im gonna put the trigger for the wet dry vac into a foot pedal of some sort.
some pics-
how it works- the home process breaks down into three components, heat the plastic, press it air tight over a mold, and suck it down onto the mold shape.
The way this contraption works is that the large arm swings up and down, and slides the rectangular cage straight up and down inside the blue frame work. The plastic is clamped inside the rectangular frame. Up top will hang heating elements from an electric stove (working on bracketry), and below will be a MDF topped table with a seal for the frame to seat against.
You would swing the frame up and lock it to heat the plastic, place your mold, once the plastic is hot, swing it down in one motion and hit the wet/dry vac to suck it down. The size and weight of the arm will allow you to put minimal force on it for ensure a nice hard seal, which will be household weather stripping.
Got some work left to do, but hopefully I should be able to churn out some random plastic stuff pretty soon! Best part is that im in the hole less than 150 bucks on this thing, and 75 was the oven! we will see what it takes to add the finishing touches, ill be pissed if I have to buy something new.
the space is about 2.5 x a little less than 2 and will allow almost a 1.5 foot high mold. (I had to keep the machine a reasonable size for the home, its as big as a fridge right now)
Suggestions on what kind of molds I should try and make once its done and works?
ideas so far-
1. Ive got my headlight doors
2. definitely a pillar pod, probably about a dozen types
3. I want to rig up some kind of cup holder. As an American, I DEMAND a place to put my coffee, screw this European fetish against drinking in the car.
4. I want to try and make the taxi dash thing, or a bastardized version
Anyway, suggestions on what to make, and any improvements on the machine would be much appreciated!
RE: Thermo forming madness - Rudolf_Diesel - 03-08-2010
It looks good, almost like the one we have at my work. I took a few pics, feel free to use as you please
Front view showing clamp frame for plastic
Heater in retracted position
heating elements and hood in place to heat plastic
vacuum table down
Vacuum table up
Pictured is the vacuum source - a vacuum generator (runs on compressed air)
RE: Thermo forming madness - willbhere4u - 03-08-2010
did you guys play with tinker toys as kids?
RE: Thermo forming madness - JB3 - 03-08-2010
beautiful! I actually got a couple of old drawer slides to make that kind of sliding heat originally. So in your model, the mold table lifts up into the plastic?
I couldn't figure how to do that without making it too heavy, or too complicated with counterweights if all the lifting and movement were done by hand. Thanks for the pics, I am going to try and complete this machine without breaking 200 bucks, this gives me some great reference!
willbhere4u- what do you mean "did"? I still do when I can get away with it.
RE: Thermo forming madness - DeliveryValve - 03-08-2010
(03-08-2010, 08:12 PM)Rudolf_Diesel ....
Pictured is the vacuum source - a vacuum generator (runs on compressed air)
Interesting, Is that a venturi pump? How much vacuum does it make and how much compress air pressure does it need?
.
RE: Thermo forming madness - Rudolf_Diesel - 03-09-2010
The vacuum is supplied via the veturi effect, it pulls around 28" Hg when the table is sealed with the plastic. It requires ~60-80 psi to operate.
Yes, the table moves upto the plastic and the oven remains over the plastic during the process. The oven is controlled with a percent timer, i.e. 50% on, 50% off during a fixed time interval. The upper part of the clamp frame is counter-weighted to assist the opening.
I actually played with legos and out in the garage, When I was a tot I figured out how to take my crib apart so I could escape. My Mom found me in the garage under my Dad's truck covered in grease
RE: Thermo forming madness - JB3 - 03-09-2010
approximately how far away are the heating elements from the plastic on yours during heating? Im shooting for about 3 inches with the electric oven elements at its closest, but that measurement is based on nothing.
The fun part will be rigging up a way to achieve the same thing as those sexy red cam locks on yours. I was going to try and adapt the clasps from around the stock MB air filter housing, or maybe an old ski boot. Those are even adjustable!
RE: Thermo forming madness - winmutt - 03-09-2010
You need to make one big enough for a spoiler
RE: Thermo forming madness - JB3 - 03-09-2010
MK3 I hope will be big enough if MK2 proves itself, heating something that long would be tricky without entering the realm of an actual professional machine.
we'd have to figure out suction and heat for a long deal, maybe the small suction pump on rudolf_diesels setup works for a long table, or maybe two at the same time? Its been done obviously, so spying has to take place.
I was thinking that an old air tank with a vacuum pump and a release valve might work best for something bigger. That way I could use the pump to create vacuum in the tank, and simply dump a large valve on the tank when I have a good seal and let the pressure difference suck the plastic down. Kinda like a rendering truck setup, but on a small scale. Then I could rig up something else to come on to give me continued suction for a time, and so on.
Is this the basic concept on rudolf_diesel's machine?
for MK2, I will stick with a wet dry vac, since I have one here, but what sucks about these projects is that you always think of a better way to do something after you are committed heavily to one path! I have all kinds of design and process improvements for MK2, which if I include, might as well be MK3. MK2 im kinda just making up as I go along so far
RE: Thermo forming madness - Rudolf_Diesel - 03-10-2010
(03-09-2010, 08:29 AM)dropnosky approximately how far away are the heating elements from the plastic on yours during heating? Im shooting for about 3 inches with the electric oven elements at its closest, but that measurement is based on nothing.
The fun part will be rigging up a way to achieve the same thing as those sexy red cam locks on yours. I was going to try and adapt the clasps from around the stock MB air filter housing, or maybe an old ski boot. Those are even adjustable!
The oven is about 6" above the plastic, the locks are available at McMaster-Carr or any other supply house, i.e. Grainger.
It was built by an outside machine shop that makes tooling for us as well.
The old machine used an air compressor that was rigged into a vacuum pump - switch in and out piping.
When running production we use a device called a plug assist to aid in getting the material into tight spots, it is very similar in shape to the tool. Pressure or as it is also known as Blow-form is used to help form the part as well. The plastic is actually sealed in a chamber as the forming process occurs. During a prodcution run we are cycling our machines at 4 secs or so and up to 16 pieces at a time.
RE: Thermo forming madness - StreetRat - 03-13-2010
(03-09-2010, 08:55 AM)winmutt You need to make one big enough for a spoiler
A front spoiler
RE: Thermo forming madness - ME262 - 03-26-2010
Hi STD first post here! So when are you going to start restoring our dashboards fo factory finish?