I've been reading about ABS cowls and all I get are bad comments about them. I'll be having to put one together soon as it comes in two separate parts in the GP extra kit. Anyone had any experience with these types of cowls that can recommend good techniques for gluing the halves together to achieve a seamless join?

Just make sure that both of the matching surfaces are as straight as possible. Follow the instructions from Great Planes to assemble it. I use Bondo Spot Putty to fill in the seams. When the Bondo has dryed, I sand it with some220 grit paper. I will then go over the entire cowl with 600 grit to get it ready for primer. When you make your cut outs do not leave any square corners. Make sure that they are all rounded off. Good Luck, Dave

What David said, and I'll add that fiberglassing the inside with some 2 oz cloth and epoxy resin is a good way to strengthen ABS cowls and wheelpants.

You should glass the inside for strength, HOWEVER, in my experience, epoxy resin doesn't adhere well to the ABS. What I do is rough up the inside of the cowl with some 220 paper, then I position A SINGLE STRIP of fiberglass cloth inside the cowl and use THIN CA to adhere it. Once that strip has dried, I repeat the procedure for the other strips (I usually use strips about 8" x 1 1/2" ). You need to get the strips smooth against the ABS before applying the CA, otherwise the CA is going to set too fast to press the strip against the ABS (getting the glass strip smooth can be a pain with wheel pants ).

I suggest doing this IN A WELL VENTILATED AREA .

Haven't done this in a long time but this is a great procedure. From the scraps of ABS cut long strips about 1/4" wide. Clamp these at either end of 1/2 the cowl. Now fit the other 1/2 cowl - this will take some delicate sanding. Put the two cowl pieces together and wick in some Laquer (dope) thinner into the seam. This will soften the ABS and actually weld the two cowl halves together along with the strip inside. It will be much more secure than fiber glass. As mentioned above, fiber glass doesn't stick well. Good luck.

Phil

I have been investigating, and it might be possible to cast a mold of the cowl once its assembled and then replicate the cowl in fiberglass. Is there anyone with experience doing this? Is it really hard or can it be achieved? I'd really want to have a sturdy cowl... Not that I'm planning on crashing or anything...

I just put this same cowl together. The only thing that I had to do different than the other posts is use an epoxy filler instead of bondo. I tried the bondo first and that ended up cracking out on me. I used some stuff that is for repairing plastic automotive bumpers. It is flexible and will not crack out on you.

Mteal

Still, is there someone with experience on casting cowls and reproducing them on fiberglass?

See if Fiberglass Specialties has one. It's a lot of work and quite expensive to make a mold and lay-up your own cowl. To make it economical you have to plan on making and selling several of these.

Hogflyer

Problem is my location. Shipping down to here is always pretty hefty.

try this link they make pretty good products.

http://www.aerofibertech.com/index.html

I got the kit today and I was inspecting the ABS cowl. It seems a lot more sturdy than I originally thought it would be. I still want to cast a fiberglass mold. I don't think aerofibertech will ship to South America.

I have already trimmed the cowl to be ready for gluing together. As soon as I glue it, I will need to know what type of filler to use in the gaps, so I can later sand it all to a nice seamless part. I read that bondo might crack under certain conditions. What is the best idea? What about a trick I read about that mentions epoxy mixed with sodium bicarbonate (baking soda) to use as filler. What is my best shot at this?

Then, when I have to sand the whole part, what grit should I use to get it all nice and even to prepare for primer?


Edit:
I found this method listed here in RCU, I think I'm gonna give it a shot.
http://www.rcuniverse.com/forum/m_16...tm.htm#1686789