I have a kit that has long been out of production (Master Scale Mustang...Jim Meister) We want to build a couple, maybe more. It has several vacuformed parts in .040, .030 and three canopies. I talked with the people at House of Balsa since they are near me. Don told me that to pull a canopy over the existing one would distort the original if not supported inside. Making a plaster mold would be posible but he tells me that it will never dry and cause bubbles. How can I go about this. It has a belly pan, upper and lower cowl, canopies, gear doors etc. ,drop tanks, cockpit sides and on and on. I can build a vacufrom machine, no problem but hold can a make plugs...I dont think I can carve them in one lifetime. I don't think the people that bought Meister Scale out when Jim died last year have the molds since they asked me if they could buy the kit. How can I make a suitable plug. Thanks in advance

See Post #17 at the following link:

http://www.rcuniverse.com/forum/m_34...tm.htm#3456943

Some say they have good luck using plaster molds but I never have used them, preferring to have a more permanent mold. I believe the key is using a soft enough wood (for carving and sanding). Since there are so many, it may take awhile to prepare your molds, but you'll have good ones that will last forever. You can use them over and over for years.

Plaster will definitely dry. I have used plaster in 1/4 scale canopies that needed at least one gallon of it, no problem.
But you will need to buld some sort of framework to support the parts.

Lars

I have heard of guys pulling a second canopy over the first because the first did not come out smooth. How do you keep the canopies from sticking to each other. I suppose I could fill the existing parts with plaster and use seran wrap, inside to keep them clean and pull over that as a plug. I realize that they would be slightly bigger (like .030) but what the hey. What do you guys think. Thanks

One suitable way would be to use your existing ABS part's and fill the part with Water Putty.
http://www.waterputty.com/

Once dried, it is rock hard and many part's could be vacuum formed over it. Attached are a few pic's of the process used to make new/thicker ABS superchargers for a KMP P-38.

Try this thread:

http://www.rcuniverse.com/forum/m_20.../anchor/tm.htm

If it doesn't link, do an advanced search with the terms "PETG and perfectionist". It will be the only result.

Good luck with it.

Thanks everybody for all the links and help...One more question, how do I keep the plaster from sticking to the original canopy and parts if I make molds that way....mold release...cooking spray such as Pam, vaseline. ???

Tucker, If you are going to make molds you first have to deciedeif they will be male or female. The majority of the time in this hobby they will be male. If you are using an existing part to make an additional copy you have to be sure you can protect it. In your case the kit is no longer available so I woulsd be very cautious. Plaster will work if you use it to make a male mold. Since plaster generates heat as it cures, I would fill the mold partially and put rocks or something in the palster to take up space and also cut down how much plaster you need to fill canopy. Less plaster less heat. Vaseline will work as a release agent. I would try all this and something a little less critical. Get some packaging material. You know how everything comes in those clear plastic packages that you have to cut open? Finally if you get a few bubbles you can always fill it with some bondo or plaster. after all these are only temporary molds.

I'm a bit late on this one but since I just did this I thought I could help.
I found plaster a bit weak on it's own but it can work great. The best way I found to make another part like a canopy with plaster is to make a frame to hold the canopy, pour in the plaster, let it dry for a week or two, spray it with fillable/sandable primer from auto parts store, fill holes or dings with body putty, sand smooth, pull a .015 sheet over the plaster mold, trim the excess off, glue the edges down, glue 3/4" wood under it to raise it up, sand with 400, now you can pull as many parts as you want. The second pull will not stick to the first. Blow some air under the second pull and bingo! You have another part. Oh yeah, buy extra plastic!

I also found that to make other parts from scratch, balsa is the easiest. Carve, shape & sand the balsa, fiberglass it, fill and sand.

It's a lot of fun when you start getting good parts. Good luck!

tke your parts and fill them with plaster of paris let dry for 72 hors then vacuform over plaster plug I have done it and it is good