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On my last model, I had a bit of an issue with doublers, even though I'd used more epoxy than I'd like, it still delaminated. Upon closer inspection, the glue was bridging between the balsa and the ply, rather than creating a complete lamination. I had it clamped with everything I could find in the workshop!

Is there any prep work to be done prior to laminating? Should I pre-sand the sheets prior to application of the glue to ensure a better connection?

I'm tempted to vac bag my laminations next time.

With electric models, where there is no need for fuel proofing, I have had good success with contact cement for laminating doublers. Bear in mind you only get one chance to get it correctly aligned!! 

If you clamp it too hard it will squeeze the glue out and what little is left will be absorbed by the wood.


Brett, what is the line method with CA, how far apart are the lines?

  1/2" is what I used, it depends on the thickness of the beads you lay down. It's shown somewhere in here, I think:





    These are the original Bill and Bob Hunter Hot Stuff videos, it's two hours worth but you *will* learn something.

    Brett

I use 4-5 lb balsa for my fuse sides and from the spinner to around the middle of the wing there is a 1/8 balsa doubler on the inside made out of the same 4-5 lb stock. I use slow cure epoxy put on with a brush. I lay it on a sheet of glass or granite with weights on top for at least 24 hours. Sometimes I put carbon veil between the two pieces of balsa. I run a PA 65 and have never had a failure. There are many ways to accomplish this and the two methods Brett mentioned will work just as good. Personally, I prefer epoxy over CA.

    When you are gluing to 5-lb balsa almost anything is good enough! Just have to be careful to seal the engine compartment up, although in this case they are talking about an electric so probably not important here.

   I have taken to using variable-thickness fuse sides of late. You certainly don't need 1/8 for the rear end, but it's nice to have a bit more meat up front when contouring the nose. I make the splice at about the high point of the wing and then taper the 1/8 down to 3/32 pretty much from about F1 back.

     Right now I have so much 3.5-4.5 lb 1/8 (and everything other size for that matter) I am going back to that for the next few airplanes, you really lose nothing weight-wise and it's a little more forgiving.

   I scanned through the videos above for the first time since, er, Derek Barry was only hypothetical, and I am surprised how much of these techniques I apparently picked up from these videos and how much of it I still use. And make no mistake, those guys were consummate modelers.

    Brett