I'm currently building a Sig 1/4 scale Cub. The question I have is whether or not you builders use epoxy or CA for framing the fuse? I understand That Epoxy will make the bird heavy and a friend recommended using CA. If CA thin or thick? If CA have you guys had any problems with it holding the plane together? Pic below shows what I have done so far and used 30 minute epoxy. It sure takes a long time to mix small qualities and would prefer to use CA if this is the standard among builders. First kit so thanks for the help. While I'm at I might as well ask this one as well. if you guys say to use CA, then on what parts would you use epoxy? I would suspect on the wing hold down, gear block and firewall. Any others?

Hi,

If I had to choose between epoxy of CA I to frame up a fuselage I would use CA, preferably the thicker one.
If I could choose anything I want I would use regular wood glue.

I use CA for small repairs or to glue hinges in. I use epoxy for mounting the firewall, attacting wing bolt plate, attaching wing halves, gluing in tailfeathers.

[link=http://www.airfieldmodels.com/information_source/construction_materials_for_model_building/adhesives.htm]Here's[/link] a link that explains the advantages and disadvantages of all the glues that are out there (atleast those that we can use).



Bart

I have built quite a few planes over the years now, and the best to use for general framework is thin CA. Medium and Thick CA is usually used in areas where you need a little extra strength, such as known stress areas, but not critical ones, such as horizontal and vertical stab attachment to the fuse frame. Some prefer epoxy for this, but usually thick CA is fine. I personally use Epoxy to provide time to set it in place properly. Thick CA is good for plywood and hardwood parts as well. Do not use thin CA on Plywood or hardwoods, it does not penetrate well, thus the joint tends to be weak.

For areas like joining wings, and firewall adhesion, use 30min epoxy only. These are critical, and there is no substitute for good 30 min epoxy. 30 min epoxy is also good for thinly coating the front of the firewall, and the interior of the fuse around the fuel tank to fuel proof the wood incase of minor leaks.

A very good alternative to CA is one that I like alot as well, and that is regulat Titebond Wood glue. It is water soluable, and easily cleans up. Also, it has no stinky fumes. The drawback, is that it takes time to dry. But, if used correctly, it really is nice stuff.

Patriot

I still prefer regular wood glue over CA. No fumes, cheaper, longer working time.
Never tried Titebond though, I use the wood glue you can buy in DIY stores.



Bart

I use a ton of thick and thin CA. Use it some and you will get a feel of where to use what. Epoxy for gear blocks, wing blocks, firewalls and firewall supports, center sections of wings and putting tails on fuses. CA everything else and then I go over all the joints with wood glue as a double glue. Adds streangth and doesn't add a lot of weight. I use a dental syringe to lay a bead in the corners. Nice!

Thanks you guys. Mixing epoxy sure is a pain, but I thought this would be best for strength. I will try using a combination of thin and thick CA and epoxy since I have plenty of the stuff.

I second everything that Patriot recommended. Good advice. Only thing I would add is that thin CA is good for "wicking" between balsa parts that are being held in place and have a nice tight fit, while medium or thick are better for placing on the parts prior to placing them against the other part to be secured to. Medium and thick will bridge a gap in a less than perfect fitting joint, while thin CA will not.

CA can be irritating to eyes, etc if you are exposed to it enough. It can sometimes "kick off" too quickly (before you can position the parts where you want them). It is also expensive, and does not have as long of a shelf life as other glues. I really like yellow wood glue (Elmers or Titebond) for framing and especially balsa sheeting. I still use all types of glues, though. I just recently used Gorilla Glue for the first time on some Robart hinge points, which worked out well. It's a Urethane glue that expands when exposed to moisture when curing. Odd stuff.

Try reserving epoxy use to only the areas that are high stress, like firewall, wing joints, and attaching tail surfaces to fuse. It is quite heavy, and as you said, time consuming to mix up.

Pilgrim

In most cases, a good wood glue like Elmers Carpenter Glue or Titebond, is far superior to any of the CA's for framing. The main reason is that wood glues handle shock (read hard landings or minor crashes) much better. Most CA's are quite brittle and will break under shock loads. Titebond is also quite water resistant.

Agree on that. For me wood glue is far superior than CA, definatly for framing. I only use CA for hinges or to reinforce the thread for servoscrews.



Bart

It appears you guys use a combination with any and all being good. I have talked with a few of the builders at my club and many have mixed emotions about using CA. They mentioned things like wicking and being brittle as well. The other concern was pertaining to non-perfect joints that aren't good and tight. Basically the attitude was that using CA was OK for speed, but then they recommend you go back over with a thinned down epoxy as a final step.

Since this is a Cub with huge WS 105", I'm not as concerned as I might be about epoxy VS CA from a weight stand point. The wing is so big, and with a twin Saito 182 on the nose I will have plenty of lift and power if I add a little weight using epoxy. Since this is my first kit I might as well build it to be strong. I would like this one to hold together and last 20 years or so like the examples I have read about. I picked up some tightbond and will give this a try. The tightbond appears to be a good alternative to having to mix epoxy in such small quantities. I will use epoxy on the stress points, tightbond for your basic framing out and thick CA where it need speed and where it doesn't seem to be very critical. Sound like a good plan?

Thanks for the suggestions.

You would be surprised how really strong wood glue and CA are. They are both much stronger than the wood itself. Try a few test with scrap wood and you will see. Expect for joining wings, firewall, block for landing gear, or super high stress areas stick with wood glue and CA. The epoxy makes a mess, is time consuming, weighs alot, and is overkill in most places.

For most jobs what I do is use both CA and wood glue. I use one or 2 drops of CA to hold the pieces together while the wood glue dries. You get the best of both worlds. Minimum of CA fumes, but the quick hold of CA glue.

Your last post sounds like a good way to go to me. Although I prefer medium CA to thick.

I'm surprised no one has mentioned the "sandability" of aliphatic (wood glue) versus the others. Try sanding down an unintended blob of CA, not to mention epoxy...

Getting some second opinions, rfw1953???

Personally, I cannot fathom building an entire airframe using only wood glue (the milk based stuff). Perhaps on a laser cut kit where everything fits with a friction fit, but on a die-crushed kit??? Waiting for glue to dry would be a serious frustration factor for me. Perhaps I am lucky that CA fumes don't seem to bother me.

I have built at least 10 kits using essentially nothing but CA, and a few of them are still flying after 10 years. I have not noticed any strength degradation in the structure...at least enough to cause a flight failure.

I always use epoxy for adding the firewall, and for attaching wing blocks and joining wing panels. Also for glueing on tail feathers. I always glass the center sections of wings, even if the directions don't mention it. I have never had an inflight structural failure in 15 years of flying.

And no...structural failures due to impact with 'Mother Earth' don't count...

I use almost all wood glue [elmers etc] for all my framing and for most everything else in building a model. It is about the strongest glue I have used nd only requires a little longer to set up enough to handle. I only use a small amount of CA and some epoxy in my airframes.

rfw, "build light to fly, build strong to crash" Since you're on your first kit I'll invoke the classic advice. No matter how big the kit is, you can easily turn a nice flying and forgiving design into a nasty pig by letting the weight get out of hand. Trust the kit designer, he put in enough strength while keeping the weight in check. Think bird wings, not bulldozer frames.

I wouldn't have started with a 1/4 Cub (and didn't), you could have learned (made your mistakes) on something smaller and simpler.

Try the various glues on some side projects or scraps, you'll find uses for lots of them.

I'd like to caution you about thin CA, it flies around easily and emits nasty fumes is you dump it on. Eye protection is a very good idea!

As mentioned above, CA-soaked balsa is impossible to sand so it's helpful to use Titebond on external surfaces.

I use Titebond anywhere I'd use epoxy.

Man, you guys have really been helpful. Much appreciated. I have made some progress in the building, which is an education in itself, but getting there. I have only assembled ARF's to date. My hanger is in good shape so I thought I would finally get around to building a plane from a kit. I chose this model simply because I have never had a Cub, and this one was available in an estate sale for 100.00. I also picked up more wood than I will use in my lifetime so the setting was right. I have taken your words of wisdom to heart and determined that all the glues mentioned serve a purpose. I am using CA, Epoxy and tightbond. Hows that?

I like the analogy of building like a bird to fly Vs. a bull dozer to crash. I will keep this one in mind.

Here are some pics of my progress. The fuse is straight and everything squares up nicely. I sanded down the rough edges and now getting ready to add the firewall and mounting box. I'm ordering a cowling from Fiberglass Specialties. I hope I have enough room for the Saito 182 twin. It looks like it will be tight.

Let me know if something looks wrong or you see a concern.

OH MY GOD IT"S MADE OF WOOD! Just joking. From where I'm sitting it looks quite good. Looks like good tight joints. And it looks square and true. You are doing fine. keep it up and good luck.

Mark Shuman

It looks VERY good! You'll like how it flies too. I use a combination of several of the afore mentioned techniques. I use medium CA as my primary glue (Brittle? Come on! I've never seen a glued joint break. The wood will break first) But is IS a bit pricey. So if a large area needs to be done, I'll do like Gringo Volador suggested... Wood glue with a few drops of CA to hold it in place.

By the way, If you can build this kit, you can build anything. It's by far one of the more difficult kits on todays market. But it will be a great flier. What engine are you putting in it? Mine has an OS 160 Twin Cylinder 4-Stroke

Hi Mike and thanks. Yeah, this one is a bit of a challenge, but I seem to be doing OK so far. I had a heck of a time just figuring out how to read the plans at first. The pictures in the directions booklet are very helpful.

I picked up a Saito 182 Twin from a friend who had the engine in a beautiful Dauntless War Bird that was very under powered. The engine is basically new with only about 8 flights on it. I do have some concerns after purchasing it. Granted, it's a bit over powered, but I I prefer to have power in reserve, and with throttle management I didn't think this would be a an over kill. In building out the mounting box and the firewall I now have a concern as to whether or not the engine will fit. If I use the horizontal thrust line and center the engine in the middle, the carbs will stick out the top the of the cowling a good bit. If I mount inverted the headers and exhaust pipes would be even worse.

The firewall has 1 degree down thrust built into the firewall, so my thought was to move the engine down the firewall and hopefully have a reasonable match for the prop shaft to the cowling. Fortunately I won't have a spinner to line up, but engine positioning has me concerned.

I ordered a cowling from Fiberglass Specialties. I'm going to have to wait and see how the cowling and the engine match up, but unless I move the engine down on the firewall about 1/2"-3/4"" it looks like this isn't going to work.

If I move the engine down say 1/2"-3/4" on the firewall, how much would this effect the flying characteristics? Think this will work, or am I headed for a more serious problem?

I use thin ca on nearly everything if its a tight fit it is a Superior glue joint to thick or medium ca I only use epoxy for firewalls, landing gear blocks and wing bolt mounting plates. I use thick ca for tail feathers then I run thin ca down the seams after it is glued. If you put faring on your tail there is no reason why this is not strong enough. Remember it only has to be stronger than the wood

Tough call Roger. If it were me, the first thing I would look at is: If I mount it inverted and run straight pipes (Remove the mufflers), how would it look? That's how I'm running the OS 160 Twin.

Worse comes to worse, lower the engine, The nose may look a little funny, but I really don't think it will affect flight characteristics (At least, not enough to notice)

Well, here is a rough idea of what I have to work with. My concern is two fold. If I mount the engine on horizontal thrust line the engine will be too high up on the firewall with the carbs sticking up a bit and the engine being high on the firewall which might cause a problem with the firewall holding, as you can see by the pics. I will reinforce the firewall regardless of what engine I use, but I sure would like to be able to use this engine if it will fit and not cause a problem with the airplane. If I move it down the prop shaft won't line up perfectly with the cowling and the prop shaft will be off center from the h-thrust line. I honmestly would prefer to not mount inverted and then have to deal with bending the exhaust headers and the pipes. Any thoughts or ideas ? Should I just sell this engine and get a 160 twin?