I know this may sound a little old fashioned. I typically use Ambroid to glue pieces like you stated. I'll pre glue the parts and then I mate them together getting glue on adequately on both parts then I let it dry. I can see some already scrambling for the door. Once dry I sand with fine sandpaper. I place the parts on a flat table aligning wherever needed and place tape over the joint. Fold the pieces back like they're hinged and apply glue once again. I lay the parts back on the flat table with a piece of used Monokote backing or waxed paper over the joint with weights on it. When using adhesives like Ambroid, Duco, Sig-Ment, they sand off very clean unlike Ca adhesives. Ken

posted at the same time!!!!  HA

 

What if you wanted to butt glue two pieces of 1/2" x 3" x36" to make a profile fuselage, which glue would you use? Thanks, Mike 

Do you mean butt glue as in end-grain to end-grain?  Or do you mean edge-gluing, with the grain running with (not into) to the edges?  In the first case -- just put all the pieces on a muddy patch of your driveway and roll your car over them.  It saves time over building an airplane that's going to break anyway, and has the same ultimate effect.  In the second case, here's what I'd do:

For any of these, you want a joint that's as close to perfect before you start -- any gaps will both weaken the structure and make your sanding issues worse.

My preference would be Sig-ment, tightbond, or other "yellow" carpenter's glue.  They sand reasonably well and they're stronger than Ambroid.

However, Ambroid ain't that bad in the strength department, and you expect the fuselage to be a bit weak across the grain anyway.  So as long as everything fits tightly, and you double-glue the joint (this is really only necessary for cellulose glues like Ambroid, and for them it's necessary), it should work.  But yellow glue would be my first choice.

Thick CA would also work, and would be way fast.  I suppose that if I wanted a plane in a hurry (and if CA didn't give me nosebleeds) that's what I'd do.

Epoxy would make a nice strong bond, but you'd have a line of Really Hard Glue right in the middle of something that you want to sand flat, and that would be a bummer.

I do much the same using the tape method and Sigment. I have found that if you sand accross the grain and joint, it will sand much smoother without a ridge at the glue joint. After the joint is smooth, you can finish up with finer grit sanding with the grain and joint.

I do much the same using the tape method and Sigment. I have found that if you sand accross the grain and joint, it will sand much smoother without a ridge at the glue joint. After the joint is smooth, you can finish up with finer grit sanding with the grain and joint.

I get these ridges that won't go away.  When I sand off the top, the stresses inside push it up more.  I had one on the bottom of a stab that was so bad you could hear the flow separation in outsides over the roar of the mighty .40 VF.  I had sanded it every whichaway.  Not squeezing so hard when I Hot-Stuff the joint seems to help, although I have one or two of these ridges on the new dog.  I could be patient and use slower glue, but the CA works a treat if done correctly.  My new Hunt foam wing has no ridges.