I'm sure most of us on here use a wide variety of adhesives, depending opn the particular place on the ship we are glueing.  I use a lot of CA, BSI brand only and different viscosities, Titebond III, 30 minute eopxy, (Also BSI), 5 minute epoxy (sparingly), Gorilla glue, and that about covers it.  As you climb back into the building you'll find what works best for you and it might be different than what others use in each place but will fit in with your philosophies toward building and strength.

After yakking about it for a while, I'm ready to start working on a Twister kit. Obviously, I can't use Ambroid or Hobby Poxy.

So do I just get tubes of Sigment, some sort of CA, and what brand of 30 minute epoxy?

   Get medium and thin Cyanoacrylate for general construction, and 5 and 30 minute epoxy. Any brands are OK, you are just gluing balsa. I use Zap brand thin CA, and Hot Stuff Super-T, but any of them will do. I use large amounts of medium and some thin for basic construction, and epoxy only for doublers. I use different brands of epoxy for lamination, West Systems or EZ-LAM - West for general adhesive, and EZ-LAM for laimination. The brand does matter a bit for some applications. EZ-LAM is remarkable for lack of self-heating and thus long pot life, which is particularly important for sheeting foam wings. Otherwise, anything is OK, hardware store Devcon is fine.

   For the doublers on a twister, I would use Hot Stuff Super-T, as described in the Bill and Bob Hunter videos. The others are a little too fast to cure. You really have to be confident in your actions doing it this way, and work very quickly. I have done it with thick CA on one surface, and accelerator on the other, but It is no better but a little more forgiving. My problem is that it always goes bad and the accelerator evaporates between my very rare uses.

    My airplanes are built almost entirely with medium CA adhesives including the (very large) doublers and the engine mounts, EZ-Lam epoxy to sheet the foam, epoxy in tiny amounts mostly for fuel-proofing. One can say what they want, but my airplanes last a very long time.

   SIG-Ment, Titebond (I), and other air-drying adhesives will also work, but take a lot of jigging and pinning which is essentially non-existent with CA. Given a choice for general construction, while I have built *many* airplanes in the distant past with Ambroid and SIG-Ment (and UHU and Duco, and other "model cement"s.), those are not nearly as good in general as Titebond (I) - much more difficult to deal with, no "grab", and poor penetration.

    Note also that you should never use *any* air-drying glue or cement for doublers. Titebond will eventually diffuse into the wood well enough, but I am not sure how long it takes. But I have seen airplanes that had aircraft ply "bonded" with Ambroid that crashed, and found the Ambroid still liquid in the middle of the doubler. It seals along the edges and otherwise, it's like putting it into a container otherwise. Titebond is better used for this by putting a thin layer on each surface, letting it dry, and then ironing it on with a clothes or monokote iron, using it like a heat-activated adhesive.

     Brett

Interesting Brett...the odds of Sigment or Duco staying uncured or losing grip are about the same as getting struck by lightning.   

Lots of different stuff works.  If I were going to use just one glue for a CL ship it'd be yellow carpenter's glue (even for the doublers, but see my comment about weeks of drying time).  I tend to use mostly Titebond, plus epoxy for motor mounts and sometimes doublers.

  Hmm, I don't know why you say that, you *never* want to use model cement for large laminating jobs. Usually it is OK, because the designs are typically drastically overbuilt, and having 1/2" of cured glue around the edges of the doubler is enough. But why use something with a known defect when the correct solution is far cheaper and far easier to get?

     Brett

I guess one reason I say that is I started building in the "dark ages" too (63 yrs ago) and built/crashed many planes...CL & RC. I scratch build to the edge of too light and always check the parts for glue or structural failure. Yes, I've found most stock planes are way overbuilt by a long shot.  Never seen or heard of glue not drying under doublers or anywhere else except for an incorrect epoxy ratio. My take is the wood breaths enough to let the glue dry. For 10 yrs or so I used epoxy on bheads/mounts/doublers but after checking crashed planes I found thin CA penetrated and held longer than epoxy and Duco held about as well as CA...but less brittle. Never had an air fame just come apart from glue failure without a crash. Epoxy doesn't penetrate and delamination failure is when it pulls the grain out. It doesn't pull off ply but does from balsa. So I mostly stopped using epoxy about 20 yrs ago. Mixing small batches of epoxy is more tedious to me than squeezing a tube. I've never used CA for doublers but use it extensively for the air frame. It's just my opinion but I believe epoxy is way over hyped. To each their own.

How long were you giving things to dry when you see the problem?  Were you laminating balsa to balsa, balsa to plywood, or what?  What thicknesses?

You're getting me curious enough to do tests!

I wouldn't expect a cellulose cement to make a good bond to birch plywood, even if it did dry.  But I think I want to laminate some scrap plywood to some scrap 1/2" balsa with Titebond, then tear it apart & look.

  Titebond will be OK, because of the extreme "grab" it seems to have - it wets the wood (literally) much better than cellulose model cement. In about 15 minutes, you will have trouble getting it apart, for that reason only. It doesn't really dry for weeks, but it's functionally adequate very shortly.

  The application for which we saw multiple examples of failing to cure entirely were 3/32 aircraft ply profile fuselage doublers to 1/2 balsa fuselages, using Ambroid or Duco.  It never actually failed because of the bond failure, but when we looked at crashed airplanes, we noticed first a very strong Ambroid smell, then upon destructive inspection, found wet-like-it-was-applied-yesterday in the middle. It was firmly stuck around the edges for 1/2"-3/4", presumably because that was ventilated well enough to let the solvent out. This after times in the range of weeks to a few months.

   That was the first time we ever attempted to get chemical-cure glue (epoxy and/or polyester resin(!)) for use on airplanes, with my Dad looking on sternly and telling us we would "ruin our airplanes" from not using Ambroid. Either worked OK, polyester resin was easy to find but stunk up the house far worse than dope, so epoxy it was. I forget the brand, this was *47 years ago*, to my amazement.

  As above, I would (and have, many times) used Hot Stuff Super-T or other medium CA, and the grid/line method, and that is far more than adequate, too.

    Brett