www.TK560.com

[tyhodge07]

1st, is there a certain ammount or space a box should have compared to the object being formed? i have a box that isnt to big, just large enough to do rc car bodies for micros and i ran a couple test bodies with just regular styrene and i seem to have a problem with it forming all the way down the sides.. am i not heating it long enough or am u doing something else wrong? also, are there any hardware stores that i could go to locally and buy sheets of lexan?

[CJanssen]

Are you placing spacers underneath your mold? I have placed my molds very close to the edge and the pulls are good with the spacers. I use 1/8" strips of paneling although pretty much anything will work as long as it allows airflow under the mold.

Sorry, I know nothing about Lexan.

CJ
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"What, you think your some kind of Jedi?"

[tyhodge07]

nope, i didnt use any spacers... you think using some sort of spacer, like a piece of thin wood would do the job?

[crashmann]

Yup, I refer to them as risers. Get some 3/4" MDF (medium brown particle board) and a jigsaw. Draw the outline of your mold onto the MDF, then cut with the jigsaw set to a 20 to 30 degree angle, flaring out from the mold outline. Use some tape to hold the mold onto the MDF piece and pull your plastic.

The MDF riser will reduce the angle where the plastic transitions from the vertical surface of your mold to the horizontal surface of the platen.

Most hardware stores do not carry sheets of plastic (except acrylic - too brittle, and "for sale" signs). Especially for Lexan, you'll need to go to a specialty plastics supplier, or a local sign making shop - look in your phonebook.

Charlie

[drcrash]

I think that in general, all other things being equal, you want extra plastic around your mold roughly equal to the height of the mold, if the mold is fairly steep-sided. Where it's not steep-sided, you need less extra plastic.

If you have less plastic than that, it has to stretch more, and you get more thinning. If you have a lot more than that, you're more likely to get webbing.

For multiple molds, you want about the same amount of room around each one, not overlapping, so spacing steep-sided molds apart by 2x the mold height (or the taller one's height, I think) is good. (Between molds, you're *more* likely to get webbing if you don't have enough extra plastic, becuase it makes a ridge between the molds, like a pup tent between two tent poles, and that ridge may suck in on itself and create a crease rather than sucking down to the platen first.)
_________________
Paul (a.k.a. Dr. Crash)

Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com

[tyhodge07]

alright, ill search for the lexan at some stores around me, im just not wanting to order some.. i might just run a styrene body for a bit.

and for this:
Yup, I refer to them as risers. Get some 3/4" MDF (medium brown particle board) and a jigsaw. Draw the outline of your mold onto the MDF, then cut with the jigsaw set to a 20 to 30 degree angle, flaring out from the mold outline. Use some tape to hold the mold onto the MDF piece and pull your plastic.

i dont quiet understand what your saying.. are you saying i want it to be cut inwards from the outer of the mold.. or outwards from the outer of the mold..

and here is what im working with, i can angle it to corner to corner and probably have better luck i assume.


(and no the mold isnt just flat, its an actual buggy mold, its just the flash, lol)

[drcrash]

The top of the riser should be the same size & shape as the bottom of your mold. It should flare outward as you go down to the platen so that its base is bigger all around than its top.
_________________
Paul (a.k.a. Dr. Crash)

Tired of buying cheap plastic crap? Now you can make your own! www.VacuumFormerPlans.com

[tyhodge07]

alright, is there a certain length i want it to go out or just a little bit.. and im making a new top piece for it, i pan to put little stoppers on the side and have it all go over the whole top of the box to where the plasitc, lexan whatever i use stays flat and straight across.. good or bad idea? oh and itll have a rubber molding around, just have to get that, i redid the top of it last night from how i had it before hoping to change my forming of the body.

[drcrash]

[tyhodge07]

alright thanks.. you think my box has enough space for it the stretch enough without getting to thin?

[crashmann]

Here's a picture of a sandtrooper radio faceplate mold and the riser I cut for it. The circles in the riser allow air to be drawn through the mold to encourage the plastic to be drawn down into the details (of course, the mold has holes drilled through it).



And with the mold sitting on top of the riser (with tape sandwiched in between to ensure the mold doesn't move when the plastic comes down):



When I pull plastic over this, it pulls down sharp along the vertical sides of the mold, then flares out as it meets the riser. I pull the riser out, then extract the mold from the plastic (using gentle tapping on top of soft eggcrate foam). Here's a boatload of pulled radio faceplates:



You trim the plastic at the bottom of the mold where it meets the riser.

For RC Car bodies, you should test with HIPS, but because they take a beating, you will find the HIPS does not last long - it will crack and split apart. Just ask Kookas from down under in this thread:
http://www.tk560.com/phpBB2/viewtopic.php?t=256&highlight=car+bodies

But the HIPS is good to practice with, then once you have your mold fine tuned, pull in Lexan or PETG. And yes, you've got plenty of room to add a riser to your mold without stretching the plastic too thin.

Charlie

[TK 109]

nice wrok charlie!

i use little 3/4" blocks of wood and put them under my molds. i call them feet. they really help me figure out how to trim the parts i need. the 20-30 degree angle idea would also help trimming, actually. i got to try this someday...
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-Alex

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[tyhodge07]

alright, were in the middle of packing to move.. this was something i wanted to get finished up over the winter.. and now i got a heads up to what i need to do.. i might even build a larger box

[tyhodge07]

i propped it up and it formed perfectly, couldnt be any better.. now i got another question.. is there a certain material i could use that may be laying around the house thats clear, i cant find lexan around here and cant order any at this time but want to get a clear body on this thing so i can get it sent out for a guy to throw a test paint on it.

[TK 109]

acrylic for windows (metal doors that swing open and closed)?

you can find acrylic in the size you need at lowe's or home depot. try looking there.
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-Alex

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