In my Sig 1/6th scale Cub kit, I was supplied with two halves of the cowl, but there are no joiner pieces for assembly. I am not sure what the cowl is made from if this affects your answer. I would assume it to be made from ABS plastic, but when compared to other cowls that I know are from ABS, it is not the same. It is not the typical opaque white, but is more translucent. How can I join the halves together? Would wood work as a joiner, or is plastic necessary? If plastic, then are there alternatives to hobby shop purchased pieces? Maybe something like a cool whip container type plastic? All your help is greatly appreciated.

I would use some plastic maybe about 1/2" wide and use that as Joiner/aligner. Using CA (epoxy won't stick) first rough up the surface with sand paper and stick the joiner to the insdide of one half first. Then use the the "ledge" created to glue the other half together. When dry lay a piece of Fiberglass cloth maybe 1" wide over seam on inside of cowl and soak in CA. Have done this a few times and creates a pretty strong cowl that will stand up well to everything but crashes. Good luck.

You can butt glue it together if the mating surfaces align pefectly. You can use dope thinner, lacquer thinner or MEK as the "glue". When applied, any of them will soften both mating surfaces, then "melt" the two pieces together as it dries.

Hold the two surfaces together carefully, then "wick" the thinner into the joint with a tiny brush. Work carefully a little at a time ensuring the halves stay in alignment as you go, and don't let the thinner wick under your fingers as they will leave fingerprints on the plastic surface.

You COULD back up the joint with a 1/4" doubler strip (preferably of the same material) on the inside of the cowl using the same method, but you don't really have to as once the cowl halves are "melted" together, they're not likely to come apart anyway unless they are broken.

SIG sells sheets of the material - check their website by going to www.sigmfg.com and click on "Sig catalog", then "building materials", then "plastic", and finally "Sig Aeroplastic".

On the Sig website, they say to glue the aeroplastic together with butyrate dope thinner. I have some Midwest Aerogloss dope thinner. Is this thinner butyrate dope thinner?

I haven't had any Aerogloss in a long time but I believe there is something different between it and Sig dope. Sig says to never use other products with Sig dope but that may just be their advertising to keep you buying only their products. I never tried mixing the two so can't say one way or the other if they're the same thing or not. But I also believe the Aerogloss thinner will probably work to glue your cowl together. Usually any of the "thinner" type products will work. I've even used acetone but it evaporates so fast it's harder to use as the glue. Doesn't stay liquid long enough to get a good "melt" between the 2 pieces.

One thing you could try is cut a piece out of the cowl (like a small scrap from where there will be an opening - like for the engine shaft or an intake hole). You don't have to be real accurate with cutting the hole (make sure it's in approximately the right spot, though) as you can enlarge it to the proper size later. You just want to get a small sample. Apply some of the Aerogloss thinner to the scrap piece and see how it acts. If it softens it and makes it "gummy" for a few seconds before drying, then it should work ok.

What I did with my cowl was tack glue it together with thin CA glue. Then, to protect the ABS from heat, I glassed the entire interior with 0.75 oz cloth and epoxy. A very thin layer of glassing. It adds very little weight, but a whole lot of strength, and the glass reinforces your seam. The outside of the seam can then be lightly filled with Bondo and sanded smooth. Now it is ready for priming.

Patriot

what about just replacing it with fiberglass?

http://www.fiberglassspecialtiesinc.com/catalog.htm