rayb

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What kind of glue is best for laminating lite ply doublers to lite ply fuse sides?
Seems like I read somewhere that aliphatic resin should not be used for this purpose but my memory might be failing me.
Thanks for the help.

JimTrainor

Yeah, I've read that too. I believe the concern is about water in the glue causing the parts to curl while the glue dries. Just pin them down and it won't be a problem. I've done it without probem. I've used ProBond recently. That works well also. Still needs pins everywhere to keeps the parts tightly together while it sets.

ZeppelinIII

Probond/Gorilla glue (same basic stuff) is an excellent choice...the more ways i try and use those the more i like them...although my preference is to use weights and not pins...

FHHuber

Yellow glue is fine... use a lot of weights to prevent the warping.

2 hour epoxy is good. You have to learn how to work with it though.

30 min Epoxy is ok for smaller laminations... if you don't mind ending up a little heavy.

Gorrilla glue is good... again LOTS of weight.

Probond comes in 3 "flavors" one is like Gorrilla Glue. One is like yellow glue. One is like "Liquid Nails" except a bit thinner.

JimTrainor

I meant the polyurethane version of ProBond.

It can be brushed on very thinly. I've never weighed it to see... but I don't think it would be too heavy. Even when brushed on quite thinly, it foams up through any existing (old) pin holes that are in the material, and around the sides of the material.

FHHuber

I know.

The most common Pro-Bond is the right stuff... but I found out about the 3 types because... all 3 were side-by-side on the hardware store's shelf. READ the label. (ooooo darn... directions [:'(] I know how that is too. )

rctrax

That'
s the trouble with probond. There is so many different kinds that nobody can tell which one you are referring to.

pete913

I've been using some Elmer's pro bond, you need to moisten the wood with a damp rag or something , just a bit, as the moisture is what cures it. Clamp or weight it, cause it will force things apart while its curing. I still like aliphatic, Elmers carpenters glue or titebond. Titebond II is supposed to be waterproof, titebond I isn't. As far as aliphatics go, Elmers is cheaper, and available almost anywhere.

Azcat59

I vote for slow drying epoxy for most uses, but that is not what I use anymore.....if you sand the mating surfaces reasonably smooth, and are very careful, medium thick CA is fine. The danger is in misalignment, with the CA setting up so quickly you can't correct it. Here is the approach: pin the fuse side down, no pins where the doubler goes. Around the top edge, and along the front (firewall) edge, securely pin some balsa blocks....maybe 1" long, 1/2" square. Make a "dry run" by sliding the doubler upwards, and forwards, against these blocks. The fit should be perfect. If so, spread a random pattern of CA on the fuse side, and again, slide the doubler up and forward against the blocks. Pin it all down, or weight it down, and give it at least 10-20 minutes to really dry well. With the surface area involved, the CA is far stronger than the wood, and the joint will survive any flight stresses without delaminating.

I hope this is clear. It will give you an accurate and strong joining with a minimum of time expired...so you can get on to the fun stuff

Clair
AMA 15654

FHHuber

just about any glue will be stronger thant he wood...

Tests were done to compare gluing stuff together with yellow glue, CA, Eopxy and I forget what oyther glue. When applied correctly, ALL had the wood break before the glue every time. (Yep... if you can do it correctly... yellow glue will hold your plywood dihedral joiner in place just fine.)

But there is also the problem... "correctly applied." Its mighty hard to get the glue applied correctly ins some places. Epoxy is more tollerant of havig to fill gaps than almost any other glue. CA is least tollerant of havng to fill gaps. (Yellow does better than even THICK CA.)

Then there's vibration resistance... and heat tollerances... and shrinkage... (some joints shrinkage of the yellow glue is VERY helpful... others ist not good.)

Learn about your glues... use them right. You end up building lighter, stronger airplanes. Light and strong at the same time is a VERY good thing.