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Peoples thoughts and experience with different glues

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Thinking Peoples thoughts and experience with different glues

Post  Yabby Fri Sep 30, 2022 7:47 am

Im wondering what different peoples experience and thoughts are about the different glues for building models. I am meaning different glues for building balsa models, glueing balsa together, and plywood to balsa and engine bearer type hardwoods to Balsa.

i have found for my models which never last longer than a season, they a cheap, quickly built, disposable type models, but I still seek for them to be strong and also for the glue to be cheap, easy to use and reasonably quick to set, where possible anyway. I have found Super Glue, I think a lot of you call it CN to shorten its chemical type name, works very well for me, but glueing wooden engine mounts to the balsa fuse I have tended to use Epoxy. I have been using the really "no name" type brand epoxy in a 25ml syringe pack as its only Aus. $2.50 and the "big name" epoxy is about Aus $15 for 25ml syringe pack. Price is a consideration here as the $Aus is only about 65c in the $US. . So all imports are hurting more now. Anyway, Im not convinced the "no name" very cheap epoxy would be as good as the very well known far more expensive brand expoxy. Ive had failures at times with the "no name" expoxy that has resulted in dissapointing to say the least flight events. Lol.

Another glue I have used is an Acetate Cement that says its designed for balsa. It seems to be quite good, but Im not sure about it in really high stress/load areas like engine mounts.

When I was a young teenager building model planes, I used to use PVA wood glue from the hardware store as Mum decided that was heaps cheaper than the glue from the hobby shops. Lol. Maybe it does have a place, I really dont know, so I dont use it. Mainly because it takes soo long to set.

Im interested in peoples different experiences as its also very much false economy using very cheap glue in parts of the model if the glue performs poorly. It seems the CN is fine for nearly all of a model, but not sure about high stress/load joints.

sunny Flying cheers

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Thinking Re: Peoples thoughts and experience with different glues

Post  rdw777 Fri Sep 30, 2022 12:14 pm

Hi Yabby,

I use Titebond II PVA for general woodwork … I don’t mind the dry time and if makes me wait I’ll just move to a different part of the project…. I have separate small building boards and just set the one that is drying aside …. It doesn’t dry glass hard like CA and I think that’s good for the frame

Certainly epoxy on engine mounts…. I learned on this forum that Locktite 60 min was good so I used it on the little glider I built and is holding up well after many flights…. So is the polyurethane finish btw

CA (CN) has its place but I only use it to strengthen up something… like the holes in control horns or faux bearings in homemade wooden wheels….

Sometimes I’ll use Duco cement which is solvent based (thins with acetone) on very light projects or parts I want to be able to remove…. I learned about this doing some indoor FF…You can brush on acetone and re- soften the joint for readjustment or removal….

A little tool made straight pins for solvent based glues….You can dip it in the glue and get just a drop …. Works with others too, You just have to scrape the glue off when it dries…Peoples thoughts and experience with different glues F5e34f10

Some of these may not be relevant but just a few things I have learned…. I appreciate your style of quick builds and fly’em like you stole’em …. I enjoy the shop time about as much as flying but it makes me a little slow… Have fun compadre  Very Happy

Robert
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Thinking Re: Peoples thoughts and experience with different glues

Post  sosam117 Fri Sep 30, 2022 1:14 pm

For me, I like using all three of the Titebond glues.
They dry slower but give you a good adhesion for balsa wood.
The CA (CN) glues are too brittle. A good example was I had built a stick fuse (rubber powered free flight), unpinned it from the board, everything was looking good, fuse looked straight, turned around a little bit with the fuse in my hands when I banged into the side of my bandsaw bench with the fuse and about 1/3 of the small sticks broke loose.

My wife laughed at me and said that I made a nice toothpick fuse.
Since then, I use Titebond to glue the sticks together, no more quick CA glue on those little 1/8" square stick guys!

As for the epoxy. I have found that the longer setting epoxy bonds much better to the harder woods like engine bearers than the quick 5 or 15min epoxy. You need the epoxy to really soak into the wood for a good bond.

If you did wing bagging, you used the slow setting epoxy for the time, but also the benefit was that the slow setting epoxy was absorbed into the balsawood to make a strong "foam" wing.

Just a summary, each and every glue has a purpose, you just have to select the right one for the right job (and stress?)
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Thinking Re: Peoples thoughts and experience with different glues

Post  Ken Cook Fri Sep 30, 2022 2:21 pm

I prefer original Titebond as it dries harder and is easier to sand. Titebond II was the first I believe in aliphatic glues to be waterproof for outdoor use and it really isn't needed in modeling. I also don't like how it dries as it's more rubbery than the original. This makes it more difficult to sand. Titebond III was designed to be most impervious to water and I don't care for it at all other than exterior grade woods that requiring gluing. Titebond III can also stain woods so if you have covering going over it, I would opt for caution.

          Laser cut wing kits really need to be jigged up and glued with CA. When you use water based glue, your going to achieve results that aren't favorable. It's not that you can't use aliphatic glues, it's just that you have to do it very sparingly and then go back and reglue. One drop of CA is much stronger in this application. The fact that charring is on the edges which can't 100% always be removed compromises the joint and CA offers a better chance of adhesion.

      Solvent based adhesives work best for sheeting joints, build ups such as cowling blocks or anywhere that glue creeps out of the joint and must be sanded flush. Most applications require double gluing in order to be effective. These adhesives sand the easiest and can be done without tearing out the balsa. Free flight builders that I know use fletching glue thinned with acetone which is similar to Ambroid. They prefer it due to weight, sanding ease and this cement offers flexibility unlike CA. If the wood breaks and you CA it, the CA wicks into the wood making it too hard and it breaks outside of the repair. Solvent based adhesive generally break on the joint.

       I prefer yellow and white glues for most of my builds, I've also mixed both for adding some elasticity to the yellow glue for areas such as motor mounts. Mostly I do these in epoxy. My preference of epoxy is T-88 which is a very slow drying epoxy and it requires overnight dry time. It can be handles in about 2 hours but it won't sand worth a ding dong or machine for at least 24 hours. I also like this epoxy because it can glue oily woods such as teak and ipe which is what I use a lot. The nice thing is that when your old oil soaked model is in need of repair, this is the epoxy to do it with.
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Thinking Ambroid Glue

Post  706jim Fri Sep 30, 2022 4:23 pm

Years ago I used Ambroid. It is interesting to see that older models built with this stuff used to have glue fillets and these have pretty much sublimed away.

You have to admit that the smell was neat!
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Thinking Re: Peoples thoughts and experience with different glues

Post  944_Jim Fri Sep 30, 2022 5:04 pm

Hi Yabby,

What you are calling CN I've never seen...iI have seen CA:
Cyano-Acrylate super glue.

Before I jump into the deep end, I build for fun, not for forever.

I use CA for stuff that must be secured quickly, but not for any significant strength. The thinner stuff cures HARD and causes funny sanding. That is, the balsa around sands away, and leaves a hard pebble unless sanding with a sanding board. Even then, I find it hard (yuck, yuck, yuck) to ensure the harder spot sands down with the rest. I remember trying to use Super Glue brand CA as a kid for fixing my old plastic Cox airplanes, and it disintegrated when touched by nitro model fuel. Maybe the newer stuff is better. I'll use gel CA for gap-filling. Again, I am concerned about exposure to fuel. The stuff must be better 30 years later, because a lot of hobbyists use it for their builds. I may try the newer stuff sometime.

I remember Ambroid. While it is no longer marketed, look for SIG-Ment, which is basically the same stuff. I find it holds joints well, and sands like balsa. The only drawback is "glue a few tonight, sand tomorrow." A similar alternative is fletching glue for gluing feathers/flights to arrows. Purchased in bulk in this context, you are looking for "nitrocellulose" glue (yellow and stinky like Ambroid/SIG-ment). Way back when, this was also called canoe glue. Joints can be dissolved by dissolving with acetone, and re-glued later. This is quite useful for when a rib is glued in wrong. I find joints hold up to stress quite well...and can prove it by saying look for my 1960 Scientific P-40...it was done primarily with SIG-ment. This stuff can soak in well when thinned, and really grabs if thinned a bit for penetration, and double-glued full strength. In fact, the tail of the P-40 was wetted with thinned SIG-ment, and double-glued with undiluted glue. I believe this is lighter than aliphatic resins. I haven't warped any pieces with too much glue...but haven't tested to the point of ruining a part.

I use name brand epoxy for firewalls to balsa for the strongest joint possible...Bob Smith Industries is the name brand. The joint is a bit more flexible (or, really, less brittle) than the SiG-ment joint. This is why it is good for high-vibration areas. I use epoxy for any fiber-to-metal work, like landing gear wire secures to bulkheads, formers, and plywood platforms, and even fuel tanks to frames. Try to avoid the 5-minute stuff. While significantly more flexible, it develops a waxy surface that makes for poor dope adhesion. Find my BHM Mosquito in MS thread and observe the engine mounts. They were difficult to paint, but absorbed the abuse. The beams were epoxied to the balsa nacelles and plywood skins.

The yellow aliphatic resins, like the Tite-Bonds yield flexible, vibration-proof joints, and would be great for firewalls and engine beams. However, they sand rubbery and will peel out of the joint unless allowed to thoroughly dry...again, glue this morning, sand tomorrow. The best part is it CAN be thinned for maximum penetration, and strengthens after penetration by double-gluing with undiluted glue (post-penetration). It doesn't soak into really hard wood very well, so I consider epoxy for high surface strength
when penetration isn't very likely. Care needs to be taken when thinning, as parts can warp if too much is applied, like when gluing two 1/8" sheets to make a 1/4" sheet. For stacked sheets, I'd consider carefully which glue to use, as there are plus/minus on each for this purpose. End-grain on both sides of a joint would be done with thinned aliphatics for depth of adhesion, double-glued for strength, and scraped of excess from the exterior of the joint to lighten the structure. I would go back later to see if excess squeezed out, and scrape the exterior of the joint before dry. The Mossie was Tite-Bond for the balsa nacelles on the balsa wing.

Last thing...I use E6000 for plastic to balsa, like canopies and cowls. The stuff peels loose like rubber cement. Care.must be taken to roll the plastic off the wood. This isn't for a penetration area, but something that needs to stick like snot on a kid's fingers. It is difficult to remove, but can be rubbed/rolled off from the wrong place. It will glue bare plastic onto a painted surface, and generates heat as it cures.

I don't like white glue for any of this. It never seems to sand well for me.
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Thinking Re: Peoples thoughts and experience with different glues

Post  Yabby Mon Oct 03, 2022 3:00 am

Thanks heaps to all of you for such detailed and considered replies I Love This Forum! Yes, I do build them quick and fly them like I stole them. lol! But, that said, I know a real weakness in my knowledge about building models, be that a quick build or slow build, is which glues to use where and even glue types etc. Whilst i dont build the greatest looking models, the assistance and advice provided from all of this input will help me build stronger models, as quick, as in elapsed time for a build is very false economy if your model disintegrates as you turn it really hard into a wingover. My planes are fast, twitchy, very maneuverable, and built very light to gain those features and launch off my launch table on my own. And I love flying them like that. cheers sunny cheers

But a number of flying incidents and obvious post flight stress to the model(s) has made it obvious to me that I need to better understand the glue(s) being used in the construction of the models. Old Bugger Huh... I have also started improving my models from a strength perpective from observing these failures and looking to understand where I need a doubler or gussett or even slightly thicker balsa and I am learning! But all that said, I have become very aware from flight failures and post flight examination on quite some occasions, that the glues I am using in various places have definitely been a significant contributor to failures.

Thanks to all of you, all of it is great advice that may seem obvious to some people, but to me it simply is not. We all have stuff we are really good at and know about, and this is a real area I just really dont! I will be re-reading all of the posts and looking up the different glue names etc. on the net, and seeking them in Oz or the same glue by whatever name it is here. The posts present a very common theme about CA and its use and also about using the 24 hour epoxy as apposed to the five minute stuff.

This is valuable learning for me! Hand Shake Beer Cheers That will help me do more of what I love which is flying my models like I stole them , or as my Lad says to me, Dad you fly your planes like an idiot... did you know it did..... lol! Did you see it go like...... lol! I think you had lost complete control Dad. lol! Yep, the old fart equivalent of an 18 year old riding a "Boy Racer" through the hills, but with my heaps fun Half A models. sunny

cheers Flying sunny
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