using pep to make pastic vac molds

[waterwarrior]

anyone ever used the pep method to mak a mold for plastic vaccum forming?

 

[aron42486]

Seems like it should work exactly the same as a clay model

 

[Fizbin]

Interesting idea. Not sure how durable it would be, but I have seen hollow fiberglass bucks used for vacuforming before, so I assume there would be little difference.

I guess it would depend on how big of a piece you wanted to form. A helmet would probably be fine, but a chest piece might flex too much and buckle under the pressure... back-filling the buck would probably be a good idea, either way.

 

[waterwarrior]

i was more or less concerned about it warping in the vaccu mold. but i guess if theres some support on the inside.

 

[waterwarrior]

Interesting idea. Not sure how durable it would be, but I have seen hollow fiberglass bucks used for vacuforming before, so I assume there would be little difference.

I guess it would depend on how big of a piece you wanted to form. A helmet would probably be fine, but a chest piece might flex too much and buckle under the pressure... back-filling the buck would probably be a good idea, either way.

beat me to it. i was thinking of filling with two part poly urethane.

so i make a plug(pep). then i fill the back with supports of foam or dowels or whatever. vacuum form that. now i have the mold in which to put whatever i want in it. preferably plastic

 

[Heatshock]

can be done.
- pepakura completed
- fibreglass/resin and smoothen with bondo (bondo however does not do well with heat and cracks)
- make a mold - and cast it in a appropriate vac forming buck; is it hydrocal I think

 

[Fizbin]

- make a mold - and cast it in a appropriate vac forming buck; is it hydrocal I think

Actually, I've found that any form of plaster/concrete is subject to chipping after a few pulls... and with vacuforming, you hardly ever get a good pull off the first or second try. :lol

In fact, I used to use Hydrocal White for my bucks all the time (can't get Hydrocal 30 in my area), but the chipping and weight got to be quite frustrating after a while, so I switched to pouring thick holow bucks from SmoothCast-385. Making those bucks was a real pain, but they are still holding up to this day and work very well.

My suggestion is to do what Heatshock said, but instead of using Hydrocal in the mold, take the easy way out and just make a semi-thick fiberglass buck (with inner supports) from it. That should solve any potential heat, pressure or weight problems and still privide crisp detail for many pulls to come... even for larger pieces.

Btw, minor flexing of a buck isn't really a bad thing, but a fiberglass one shouldn't warp/flex if built properly. Just make sure your supports are vertical (i.e. from the highest points of your pattern interior to the vac table surface).