Here is what I have been up to.....

I have been working a little here and little there, You know "A piece here and ... a piece there..." "The blower man the blower!"...sorry got side tracked there MadMax is on!

I have been slowly working on my molded wing. Here is what I have so far.

First I mad the plug, the half wing on the board. I cut my own foam core from 2lbs foam. Tough stuff. I didnt core it out, no need. Then I cut it half from LE to TE. Then I glued it down to a flat piece of wood. From there I sheeted and finished as usual all the way up to the polished clear.

Then I laid up the female mold from there. I have tried this three times with different materials. The first was with plaster. No luck there. On a part this large it dries uneven ans to fast and pulls off on its own and is warped. Not to mention it weighs a ton! Then on a lark I tried 45 minute painters mud. It pulled a perfect mold of the wing. I mean perfect. Yet once it fully dried it cracked. I thought it would but I tried anyway. These materials had no ill effect on the original plug. From there I decided to go the real way and quit messing around. After some pointers from John Grigsby I made my own Gel Coat. I mixed West Systems epoxy in 1 oz increments and mixed in tons of microballoons and milled fiberglass, for some strength. I had to get a smooth covering over the plug with a 1/16" thickness over all of it. Once it had about 4-6 hours drying time on it I laid in two layers of fiberglass. The heavy duty stuff from Home Depot and cured it with more west systems straight epoxy no more filler. After another hour then I placed some randome pieces of wood on there to give it some strength length wise. Then I added in some expandable foam to make the thing have some sort shape once it was off the plug. Well for some weird reason the foam expanded and then started shrinking. After the foam dried it started to distort the female part and pull it from the plug before it was ready to release. I quickly started to remove the foam. It was actually quite easy to get the foam off of the part. Below is what I have left. I need to build up the back of the part to make it usable but the part itself is excellent and I think I can pull some cool stuff off of it...Wish me luck.

I got to give credit where it credit is due...John Grigsby helped out alot with the ideas about epoxies. Windy helped out alot on this with the video of how he built the MAII wing.

Doug, what does Bill Wilson use on the fuse molds he makes? I thought he was using plaster, but maybe it needs to be thinner or something. Lets see...what sets up hard, doesn't shrink, doesn't expand, doesn't warp, doesn't crack...hmmm...LOTS of epoxy??? Pure fiberglas resin? I haven't seen Windy's video. How did he do it different?

When you get it, I think we all might be very interested.

Try http://www.tapplastics.com/
Look under molding supplies.

But then again, it looks real good from here!

Wonder how much that dental mold gunk costs?

Craig,

Bill does use plaster. It works good on smaller parts for sure. It would probably work for this to but I dont have much experience with it and didnt feel like learing it all. It is real easy to use on small stuff like cowls and such.

Windy did his very similar to what I am doing. I am really following him and tweaking a bit. Except he used the REAL Gel Coat material, the actual part you spread on the plug. It dries harder and is a thicker material. However he did get away with using the foam as the support along the back of the mold.

He then vaccum bagged the parts in it with a bleeder ply that pulls all epoxy out. Then once the part is fully cured there were bunch of pinholes in the carbon, correct by the way if that happens. Then he covered it in Silk Span and finished as normal. I could not believe what I was seeing when he did that. Deffinantly NOT the way I am going to approach it. I am doing this to get away from having to FILL wood and finish it.

I am probably going the Bill Wilson method of layup. Crows foot glass, leaves no trace of a weave or grain once cured very smooth, 2.9 carbon cloth, 1/16 balsa sheeting, 1oz fiberglass or E-glass on the very inside. Pull vaccum at about 3-4 lbs on the gauge. The list here goes from the outside in. Crows foot glass leaves a perfect smooth surface for finishing on straight from the mold.

Anyone have any ideas on layup let me know.

Hi Doug:

When I was younger, I was responsible for tooling for production fiberglass yachts. So I've been there.

There are a couple of other folks on here with similar background.

Anyway, for the mold, I would recommend that you get ahold of some tooling gelcoat--orange or black. It is formulated specifically for that application. You want zero porosity and no shrink. THe porosity is a big problem--especially if you want to mirror a high surface finish in the final part. THis means you cant use PVA. THe finish wont be there. Any porosity on the mold surface can cause a stick and worse, it will lead to pull-outs and the resulting mold repair.

From Gel outward, a heavy glass mat and west epoxy first, then any glass and epoxy and reinforcement until it is stiff. Let the layers cure normally so there is no print-through from any bracing. If you add wood stiffeners, make sure they fit and use 1lb foam "pads" under them. THis prevents shrinkage from pressing the rib piece into the mold. After a while, they WILL print through.

Make the surface finish and firness of the plug as good as you want the final part and avoid anything but buffing and waxing on the final mold. Any sanding will open up micro-porosity.

We have used straight West epoxy for tooling finishes instead of gel. It is excellent as well but doest hold up quite as well. Of course we were pulling dozens of parts from a mold. If you use west as you did, I would avoid adding anything to it except a little Cab-o-Sil to thixo it. Paint it on and let it gel, then keep going with the heavy mat. After that is cured well, continue. Dont rush the layup and dont let a build-up get hot in cure. Milled fibers, etc will end up poking through the surface and cause micro porosity.

Wax, wax, wax!

As for your part lay-up schedule, It sounds too heavy to me. try the layup on some flat test panels before you do a wing (I'm sure you have already thought of that) uses similar size test strips like 1 inch wide by 6 or 8 inches long--fully cured--to test the panel stiffnes and impact strength.

Try to use a balanced schedule--same layup on both sides of the core.
Also, I really like the Carbon/Kevlar composite weaves avalable now. It gives the stiffness and light weight of CF and the impact resistance of Kevlar. For cost saving, consider all Kevlar mat and weave.

For final part finish concerns, the real problem, as Windy found and you observed, is that if you dont use a gel or epoxy layer first, the cloth or mat will leave voids. Attempts to richen the resin ratio at the surface leads to weight gains. The only suggestion I have here is to work with fabrics and mats that have the right binder applied--failure to do so will cause voids. If the binder allows the resin to fully "wet-out" each strand, the void issue is immensely reduced. If the fabric people don't know what binders are on their product, and what they are compatible with, find a supplier that does know. Finally, in this same area, make sure that the temperatures are warm enough to reduce the viscosity of the epoxy. If you want to get whole hog, use the specially blended laminating epoxy. It is designed to be a little less thixotropic and will therefore help reduce the mini-voids.

By all means take advantage of the customer service and application engineers at the epoxy and fabric companies--they usually can give you alot of advice worth having.

You've done most of the hard part already! I'm anxious to keep following your progress.

Check out F4FGuy and his lay-up schedules for his CF molded skins.

Hope this helps a little.