wrongwaywayne

What is the easiest and best way to make a mold from an ABS cowl? It is for a Great Planes Extra 60 size. The ABS one is way too heavy. What is the best type of wax? Is this worth all the extra time?

CafeenMan

I would just buy an after-market cowl. You could use the GP cowl to make a plug, but by the time you buy all the stuff you need, you'll probably save about twenty-five cents over buying one already made.

I don't know who would make it though. Try Fiberglass Specialties.


This is the simple version to making your own - there's more to it, but just to give you an idea.

You should fill the ABS cowl with expanding foam to keep it stable. Coat it with a release wax and then make a mold using a traditional technique such as laying up fiberglass over it. You'll need to make a left and right half and watch for under cuts.

Then use the plug to make a new cowl.

An easier way, but less accurate is to just carve a plug out of foam, lay up glass cloth over it and remove the foam. I've done this lots of times with the foam tack-glued to the fuselage and several wraps of tape around the balsa nose up to the firewall. I used car wax on the outside of the tape and lay up the cowl in place.

KC-135

My Feedback: (3)

try stans fibertech

rchawaii

I've done the same., If you use simple wax paper taped on the foam the gladd will come right off. just be sure to try to keep the wrinkles in the wax paper to a minimum if you go that route.

wrongwaywayne

Do you think saran wrap would work?

I've heard about some tecnique with a ladies panty hose, but not sure how that works either?

Johng

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I copied plastic parts for my Stinger 120 by molding from the ABS originals. Take a look at this thread:

http://www.rcuniverse.com/forum/m_48...r/tm.htm#48000

However, unless you already have glass & epoxy around, you might as well just try to buy one. There is a learning curve to molding good parts, even when you have a plastic master to start with.

rchawaii

Wayne,

I don't know those answers- while saran might work, I would think it would (or may) be hard to get it off the part when the resin is cured without leaving some behind, and I have never heard of using panty hose for molds for f/g making-it doesn't sound like a compelling idea.

John uses a similar method to me, but he (no offense to him of course) left out lots of details-details we just don't think about when making things ourselves.

For example "LAYING UP" while a term for fiberglassing, is a method and is more than a little work and can be tedious and frustrating if you have no experience.

If You are going to paint your parts, unless you're good at making your parts, you will have to sand them, (sometimes very much so) prime and paint-unless of course you don't give a squat about what they look like.

I recently made a cowl for my scratch built bipe project and it came out pretty darn nice(using blue dow foam for the plug-since I had no prototype). It took some sanding and polishing, but alls good. If I can remember this thread, I'll try to post a pic of it.

John I would suggest (since your mini-tutorial is good), you should offer to make a complete detailed tutorial for it in it's own thread (if you haven't) Seems like you have the process down pretty good bud and thanks for sharing your work..

wrongwaywayne

I agree a tutorial would ceratinlye help.

As far as pantyhose go. You use them over a male mold. After glassing and epoxy - the mold - you stretch the pantyhose over and it hold everything down and makes a smoother surface while it dries. After you take off the finished piece, sand, fill and paint.

That method wont work for my cowl.

I was wondering if you should assemble the whole ABS cowl and then make the mold rather thatn from each individual piece?