raron455

My Feedback: (38)

FIrst off I have read a ton of posts, and searched alot before Posting this question, Iam just still a little confused,, Mainly about when and where to use what glue,,
I am building a 50ccultimate biplane,, and am gluing the two top wings together,, I want the strongest bond,, I have read the comparisons between Ca and epoxy,(even read the great planes article) just still a little hazy though, In my opinion If Ilightly sand the two mating surfaces of the wings, put a coat of epoxy on each half along with the dowels, and put them together and let them dry ,, that would be the strongest bond I am going to be able to get,, However I am reading where some folks are using titebond (carpenters wood glue) to join their load bearing connections,and swearing that is is just as strong as epoxy. I am not too sure about all that, SO I am asking my fellow members here,, what do you know or think about it. I know Ca also has its strengths, but most say on a big joint that has force on it,, use expoxy. I am planning on using Ca on certain joints,,LIKEMy robart hinges on the control surfaces and such,, I am asking becuase I am still learning,, Thanks in advance for any info or input

partisan

My Feedback: (1)

Definitely use epoxy. It's the strongest bond you can get.

Some say if a longer curing epoxy is used like 1 hour, the epoxy has time to saturate the wood being bonded and makes it stronger. It also gives plenty of time to make any adjustments and double and triple checks on alignment.

SunDevilPilot

The bond of epoxy and modern PVA Glue (Standard wood glue) exceeds the strength of the wood used to build our models. The benefit of epoxy is it's ability to fill gaps. Joinery is always important but epoxy is a little better at filling a gap while maintinaing it's strength.

Figure this..... If the root ribs are made of plywood then some of the strength of the joint is whatever glue the plywood manufacturer used to make the ply.... The epoxy would only be joining the innermost layer of the ply together.

I gave up CA glue so I have no thoughts about it anymore.

This only applies to wood to wood joints. Composites are a whole different issue.

Do an experiment, glue some wood together using differnt glues and the next day try and tear it apart. You will be breaking the wood first.

I'll attach a photo of the root rib after it was torn from the wing of my Cub during a crash. As you can see, the plywood failed before the wood glue joint did, evident by all the wood still stuck to the wing's sheeting.

My humble opinion.

SunDevilPilot

Ejiro

My Feedback: (4)

Just something to add here as well is that you may want to reconsider using CA for the Robart hinges - gorilla glue or 30 minutes epoxy will be a better choice.

sensei

Sun Devil Pilot is right, those adhesives he mentioned are stronger than the wood itself. Myself, I design everything in wood to be bonded together with CA, if the wings and tail feathers are foam core with sheeting then I use thinned epoxy or Gorilla glue and always gorilla glue on Robart hinges...

Bob

DGrant

My Feedback: (4)

I use epoxy and CA exclusively on glow/gas powered planes. I use carpenters glue on furniture and such.

The major joints, IE engine-mounts, firewalls, wing-mounts, tail surfaces, gear-plates, wing-joints, etc.. all get 30min epoxy.. and I use clamps on everything here.

I plan the gluing well before hand, and practice fitting it, fine-tuning it for the best fit possible.. Its sometimes surprising how much difference a few swipes of sandpaper in the right spot does to make a perfect fit.

Using popsicle sticks(from Michaels), and a 4x4" piece of card stock.. its easy to mix and apply.. I even use it on small electric firewalls and tail feathers.. I just use a tooth pick instead of a popsicle stick.

Clamp everything if you can too... I use a "tie-down strap" to join wings.. just have to make sure to pad where the buckle is.. other then that epoxy is my prererence here for sure... and I can get some pressure on the joint.. thats where the epoxy soaks in.. its one of the best for penetration. Its also very good thinned with denatured alchohol for a firewall finish.. it looks pro and lasts years..

As someone stated.. a bond is only as strong as the surface its bonding too really.. such is the case with plywood... but my bet is epoxy, as the resin base does seem to creep into everything you let it.. and some places you don't sometimes.. it gets easier with time though.

As for CA... I love that for wing construction.. ribs to spars/leading edges.. CA in a structure is great stuff.... and is very compatible with balsa.. the medium CA is probaly my favorite.. I rarely use accelerator though.. it makes the CA too brittle for my liking.. but its great for most balsa related structure.. for sure.

A good 30min epoxy, and a good med.CA glue would build any kit or ARF on the market I believe. I hope this helps a bit. Have fun.

Gray Beard

My Feedback: (-1)

I just finished gluing these two wing halves together so thought I would show you. Wings use what you will see called wing joiners to hold them together. In my cas on this wing I have a joiner on both sides of the main spar and one on the back spar plus I added a joiner to the leading edge and trailing edge. I use epoxy for this process, 30 minute gives me the working time needed and is a nice strong bond. After inspecting a lot of crashed planes I have discovered epoxy doesn't really penetrate hard wood like wing joiners but it does soak in a little into balsa.
Carpenters glue and CA is what I use for balsa but I use epoxy on any hardwood. Carpenters wood glue will work OK on hardwood but CA doesn't work well at all.
Epoxy or Gorilla glue is what I use on plastic hinges, either flat or pins. Pacer used to make a good hinge glue for plastic hinges but no longer makes it?
I keep about 6 different types of glue on my bench and use them all but CA and epoxy more then the rest.

acdii

I started building my 4*120 wing using thin CA to tack the parts, then go over every joint with Elmers waterproof carpenters glue using a syringe. I ran out and picked up some titebondII, I found the titebond to be better than elmers, it sticks quicker, and is easier to apply.  I did the same with the fuse, tacked up the parts. then ran a fillet of titebond on all joints.  I then used epoxy, of the 30 minute kind, mixed with fiberglass powder on all the firewall and landing gear pieces.

Needless to way, this plane will not fail from a bad glue joint.

dbacque

My Feedback: (3)

Robart recommends epoxy for their hinges. I wouldn't use anything else on them. And they're the only hinges I use.

Dave

speedracerntrixie

My Feedback: (29)

Epoxy is going to be the strongest you can use in high stress areas provided it is a quality epoxy and has been mixed correctly. My rule of thumb is to stay away from any of the 1:1 ratio epoxies. I do alot of fiberglass lay ups so always have laminating resin around. I can add milled fiber and Cab O Sil to make it any consistancy I need. It is easily double the strength of Devcon or Tower 30 Min epoxy and is actually cheaper. The drawback is that you buy a quart at a time and it must be weighed when mixing.


For Robart hinge points I always use polyurethane glue such as GG. Works great and holds better then epoxy. Whichever glue you use, roughen up the hinges with some 220 grit first.

LargeScale88

I've glued wing panels together with Thick CA, Wood Glue, and 45 minute epoxy, and neither one of them have failed yet. of course, I did use a 1" width fiberglass resin and cloth strip down the center, but that doesn't support all the stress.

In reality, any popular glue is going to be stronger than the wood itself. Picture an airplane crashing, you go pick up the pieces, and 99% of the time, the wood snaps in half, and the glue joints are still holding together. If the glue was weak, it would have broken at all the glue joints, and you could almost just glue it back together.

BUT, epoxy gives you working time, it can fill gaps (as stated in above posts), and if your two joining surfaces aren't exactly tight with each other, epoxy will still bond with the two and hold it together, where as CA and wood glue would pretty much be a fail as far as having a good joint.

Use epoxy like everyone says, its just the common glue for that use.

Hope i helped!

Jason

sensei

Alright, so you have heard several opinions, now all you need to do is figure out whom you should listen too...


Bob

Handiman

My Feedback: (2)

Do a test for yourself.
Glue a small box together from Balsa, Plywood, Basswood, others.... let it dry and then break it. What happened.
I bet you will find that a good wood glue will hold a good joint and the wood will fail.
The other key here is when using wood glue your joint must be a good fit. If the angles are off then it might fail.
I learned many years ago when building speaker boxes. That the staples are for holding the box together so the glue can dry.
We dropped a 3' x 4' x 2' MDF box from a building roof and not a single glue joint failed. The wood broke into 20+ pieces but the glue held.
Be reasonable with the dry time. You wouldn't fly a plane 1hr after glueing the wings.
Good Luck