2112troy

iTrader: (53)

MUST use polycarbonate for that.

Taylorm

Do you guys mix the water putty by hand or with a drill/spade bit like drywall mud??...... Also on platen size... How much bigger do i want my platen than the mold to get a good seal???

g-live

Anyone using a colored plastic at all for forming? Are there any thin enough and durable enough to use for forming?

Greg

g-live

Anyone use colored pvc for any bodies or parts? I see it comes as thin as .040"

Greg

Lone Star

iTrader: (3)

SABIC makes colored lexan. We have used the black and smoked types on aircraft.

Josh L

iTrader: (1)

PVC has a heavy chlorine content, dioxins are released during the manufacturing, and or heating/burning the compound.
Dioxins hold carcinogenic emissions.
I learned about this before using a 100watt lasersaur (laser cutter) in the materials do's and don't list. The chemicals release of certain plastics makes you wonder why we even are allowed to have the crap.

Anyhow, why hasn't anyone 3D printed a mold blank yet? Creating an SVG file would be super easy and the accuracy of mold lines and proportions would be exact every time. Once printed and assembled you could make a female mold with latex using the printed set, and then make as many master molds as you wanted to.

bigcracing

iTrader: (32)

Trying vacuum forming a 12 th scale body and having problems with the plastic coming down to the box on the sides. It is .020 lexan and pet g vivak and just doesnt seem to pull it down. Any help would be great

Josh L

iTrader: (1)

It would help a lot with some pictures with the model empty and one of the failure attempt as well.

Lunchie

if you are having trouble with the sides, then try and raise the mold up higher. that way the lexan wont be trying to go out sideways at the lower body line and instead will be still pulling vertical.

Has anyone tried using a good old car as the vacuum source? an engine can pull over 20" of vacuum at idle and more when revving down. you hook a pipe to the inlet manifold and attach to your tank (or even straight to the vaccum table??)

Lunchie

how do you stop the vacuum tank from sucking the air from the shopvac and not the mold? surely the 20" of vacuum would just suck the shop vac bacwards and not the holes in the table??

also what volume of tank would you need? im considering using a 9kg(20lb) propane tank, what size piping between the tank and table?

Lone Star

iTrader: (3)

That propane tank is going to stink for a while. I use a 12 gallon compressor tank and 1" pvc for all plumbing. Make sure the plastic is a lot bigger than the part with .020 so there's more stretch room to pull down the sides. It sounds like you are cooling off too much.

g-live

I ended up with a real nice set up with a large area to form. Am working on some dirt late model bodies. Any recommendation on materials? I am thinking mdf board for the sides and decks of the bodies and then Dunhams Putty for the front ends and roofs. Has anyone combined like that?

Greg

HugoW

Hi guys,

I've built my own machine last year and I am slowly developing a method to make good bodies out of lexan. Here's a recent video:

+ YouTube Video

I know this is not a good pull, I made the sagging too big and there was not enough heat in the material. I also feel my vacuum cleaner is lacking power, I am looking into a better solution there.

I heat the 0.75mm lexan for an hour at 5 amps (230V), no clue what temp that is, to get the moisture out. I then raise the amps, create the sagg. Switch off the heater, turn on the vacuum (cleaner) and pull the sagg over the mold. Touring cars go fairly well, F1 style is still difficult. I will dig through all these pages in the coming days, but I have two questions I'd like to ask now:
1) I feel the sagging cools the material, as it comes into contact with more ambient air. Would adding a few alloy bars across the system to create multiple smaller saggs help?
2) On all bodies I have made so far, the side bent outwards after I cut the body to size. Like on a touring car the part between the wheels bends outwards like half an inch. As long as the body is in tact, so no wheel cutouts, the lot stays straight. I think it has to do with stress in the material, maybe because it stretches over a cold mold so the inside cools faster then the outside of the material. As long as there are enough folds in the material, it all retains it shape, but when the shape it rather flat, the material bends. (I hope I described the problem clearly). What remedy could I try?

Cheers,

Hugo

the incubus

iTrader: (17)

Never heard of pre-heating/drying for vacuum forming processes. Wonder if that's affecting the pull?

As for the tides bowing out on you, a heat gun might do the trick to allow you to settle back into the correct position. Hold the body on it's side and apply heat to the opposite side until it starts to give and then quickly turn it over and rest it evenly on the heated side until it cools.

I've had to in a pinch, alter wings for my kids' buggies that had dips in them that would not allow me to mount them on my car. A bit of heat and a couple blocks of wood and the mounting area was left nice and flat.

Very nice rig you have there. Have you ever done wings? I have a design I want to make but I need to make a 2-Up mold of it first and then find someone to make them for me. It's a fresh take on a long forgotten wing from ages ago. Can't even find a single anything on the company. It was called Team hammer and their wings were the very best in the industry but they never went big time.

Josh L

iTrader: (1)

Very cool guys.. I am interested in seeing those wings to incubus. Do you have any pics of what your talking about?