Slow CA
 

I was wondering if it were to be a good idea to substitute Elmer's wood glue for slow CA. It's for the main spar on an LT-40.

RE: Slow CA
 

as long as you can keep the spar in place tight against the ribs that glue selection would be better! Wood glue would stay flexible and move with the wing, where as the CA would be a more brittle bond.... both are acceptable, its really a matter of how long do you have to sit and watch glue dry!


Rod

RE: Slow CA
 

I use aliphatic resin (Elmer's, Titebond, etc.) for nearly all construction joints.

If you want to read more about types of glues and their applications, see AirfieldModelsAdhesives

RE: Slow CA
 

hmm...it says not to use for high stress areas. Would a main spar not count as a high stress area?

<br type="_moz" />

RE: Slow CA
 

Aliphatic type glue is the only logical glue to use.

Ca to be used for tacking only.

Epoxy for high strength locations.

You do not have to watch the glue cure. There is always somethng else to do while the glue cures.

Who use CA for all their build to save time also end up saving time for the life of their model.

All old timers know that by experience.

Good gluing practice and covering that does not tear is always worth any extra effort while building.

Zor

RE: Slow CA
 

Zor - not sure what point you're trying to make. Will you please say it a different way? Thx.

RE: Slow CA
 

Hee Hee ___laughing ___http://www.rcuniverse.com/forum/js/f...sn/biggrin.gif.
Semantics is a great thing.

The point I am making is that if a builder use CA for saving time in his build the model will also have a short life because its first crash will result inmany individual pieces instead of remaining in one piece easily repaired.

The model will also save time having a short life. http://www.rcuniverse.com/forum/js/f.../omg_smile.gif.

Zor

RE: Slow CA
 

I've seen more pilot and radio problems crash more planes than any type of glue joint.  If you look at crashed planes most of the broke pieces are of single wood parts and not the glue joints.  Now if its a weight thing Aliphatic glue is lighter than CA.

That being said I just built an LT-40 over the winter and used slow CA on the main spar and it's rock solid.

RE: Slow CA
 

I have to disagree with this statement. My Smith Miniplane was constructed entirely with CA, and 6 years later is still like a tank. And I am not gentle with it, either! [>:]

RE: Slow CA
 

A different twist - Zor referred to "all old timers"

Before ARF's everyone built. The ones that were in a hurry built their models "in a hurry" disregarding attention to details. They also used CA BECAUSE they were in a hurry. As a result the finished product reflected them being "in a hurry". Probably didn't last long.

Today, the fliers that are "in a hurry" buy RTF or ARF products. Those of us that build are NOT "in a hurry" and we pay attention to details whether we're using CA, AR, epoxy, hot glue, or any other adhesive. As a result, pilot error or an occasional radio hit (or other pilot hit) are the reasons that today's kit airplanes fall out of the sky NOT because CA was used.

Hope that that makes sense ... (it did when I typed it ;))

After thought - the only airplane component failure that resulted in a lawn sale was my 1st plane - SIGKadet Sr. ARF - the wing collapsed just outside the "main spar doubler". Bob Nelson of SIGsaid that there were "build"problems with the wing and if I'd send it back SIGwould replace the plane. Oops - I field stripped all of the serviceable bits and tossed the rest in the field's dumpster. Arrrggggg - there is a lesson here ...

RE: Slow CA
 

Congratulations for being a good pilot and not crashing your Smith Miniplane for 6 years.
I suppose you have had many hours of enjoying flying it.

As I said before, it is in a crash that we see the difference.
If you havea badluck you may agree with me and count the number of pieces your tank has produced.

Of course the number of pieces will vary with how hard it hit the obsruction.

I never forgot the fellow who wanted to recover his ARF to change the color scheme.
Pulling off the covering he found that the covering is what was holding his frame together.

http://www.rcuniverse.com/forum/js/f...sn/biggrin.gifhttp://www.rcuniverse.com/forum/js/f...sn/biggrin.gif

Zor

RE: Slow CA
 

I would suggest epoxy if at the wing root.  Either CA or aliphatic for the rest.  If only because epoxy is completely fuel and water proof and not brittle.  All will work for a few years, but the stress would eventually get to CA or aliphatic.  It depends on just how much and how often it is stressed.  They might work, but why take a chance?

RE: Slow CA
 

I referred to "old timers" as the fellows that had to build their model if they wished to fly before ARFs and RTFs were available.

Your second paragraph illustrates exactly the point I was making.

I certainly DIDNOT imply that models fall off of the sky because they were glued with CA.
I only referred to the results of a bad crash.

What you wrote does make sense to me.

No doubt there is a lesson from your Sig Kadet wing folding. However we do not really know the reason for the folding. It may have been poor glueing but it could also have been weak spar material or a covering that did not add strength to the frame.

Zor

RE: Slow CA
 

I respect your opinion of being "rock solid" but it remains just an opinion ___does it not ?

Weight wise ___I cannot see any advantage of saving on glue.
I built an 10 1/2 lbs model and used less than 4 weight oz of glue and that is with double glueing and making fillets at all glued joints.

Zor

RE: Slow CA
 

Zor - SIG told me that it was a "wood specification" that needed to be upgraded. If I understand that statement correctly, it was built with a lower quality grade or perhaps smaller in dimension than it should have been.

Also, the manufacturer used hot glue. It's my understanding that hot glue creates a "bond by interference" joint rather than an "bond by absorption". Every time I handled the wing or fuse and heard a faint "crack", unknown to me but a joint has just failed.

RE: Slow CA
 

On some rather large models, yes, a wing spar is a bit more stressed than a single rib for example. But on an LT 40? This thing weighs, what, 5-6 pounds maybe? The spars are lightly loaded in this situation and Elmers works great ....

RE: Slow CA
 

Like any glue it can be misused.

MinnFlyer (RIP) shared advice given to him by his father when using AR - apply the glue and wipe it off with your finger. What remains is enough glue.

Of course - technique does NOTapply to CAhttp://www.rcuniverse.com/forum/js/f...bananahead.gif

RE: Slow CA
 

The only thing to use is Slow Cure Epoxy.

RE: Slow CA
 

You just hit a wasp's nest with a broom ... :eek:

RE: Slow CA
 

The wing's main spar is the highest stress point in any aircraft. Every other component (part) of the aircraft rides on it and depends on it's integrety.

I tool a look at the LT-40 kit build manual (http://www.sigmfg.com/BuildManuals/S...detLT40P2.html) in reference to building the wing. I see that the wing spars are hardwood and that there is a balsa doubler bonded to the hardwood spar. Is this the area that your questioning using slow CA on?

Which type of glue to use where in building a model will turn your simple question into pages and pages and pages of endless debate. To a certain degree, the type of glue you use is personal preference. There are some glues that work best and should be used in certain applications. The Airfield Models presentation on adhesives that John Gilmore posted a link to is a great reference. This reference will help you build a knack for what type of glue to use where on your model builds.

Personally - AGAIN - personally, I do not like what CA does to balsa. By nature, it works itself into the pores of the wood and hardens, thereby hardeneing the wood. I've been building by the rule of thumb that if a balsa area must be sanded, I do not use CA. I don't use CA in high-stress areas because CA depends more on it's own strength instead of the strength of a adhesive/wood bond like in the case of aliphatic resin or epoxy. Once again, this is my personal preference. I can point to one large-scale (1/4-scale, 1/3-scale) VERY skilled scale builder that builds his models primarily using CA and has not had any problems. Here in this thread Dope Fiend reports that his Smith Miniplane is just fine. Can't argue with sucess and experience.

I build primarily using aliphatic resin (aka: "carpenter's glue") and Titebond is my brand of choice. It spreads and sands nicely. For high-stress areas (firewall, landing gear, etc.) I use :30-minute epoxy. Again, to each his own. The main thing is that you use the best adhesive for the application. In your case, I would bond the balsa doubler to the spar using aliphatic resin. My technique is to put a small amount of glue in a small plastic mixing cup and spread the glue on the woods using a small, flat artist's paint brush. Easier to control than applying straight out ofthe bottle.

Speaking of wing spars, here's an interesting video on the B-777 wing spar stress test:

http://www.youtube.com/watch?v=Ai2HmvAXcU0<br type="_moz" />

RE: Slow CA
 

Well I have Elmer's Glue, Sig Bond and Sig Epoxy...and I'm thinking either the Bond or Epoxy, but leaning more toward epoxy at this point. I have realized, however, that I probably need to put some fillets with the Elmer's on the horizontal and vertical stabs, cause the CA fillets aren't that great.

RE: Slow CA
 

FT6 - SIG bond is a great wood glue whose joint sands beautifully - however - it is not one of the stronger ones. In the LT40 wing spar glue - Elmer's or epoxy would be my choice.

RE: Slow CA
 

Sport epoxy is not fuel proof. if you have every noticed that firewalls coated in epoxy will eventually turn color because the fuel soaked into the epoxy. besides all this does is add weight to the plane.
Acrylic paint is the most fuel proof product that i can think of.

OP as far as super glue goes you can use it on the spars and the whole build of the plane except fire wall and wing hold down blocks. do not use kicker on the super glue as it will reduce its holding strenght a lot. use slow gap filling on the spars ribs and what ever else and dont worry. you must let it cure before you remove the pins/ta[pe or what every you use to secure.

for any kit i build i only use elmers wood glue on everything including the firewall, wing hold down block and even to join wings. to me this glue is the best out there for wood kits.............

RE: Slow CA
 

Old timers used Ambroid!

RE: Slow CA
 

Explain double glueing. What were the fillets made of?

RE: Slow CA
 

Wood grain absorbs glue - different woods and grain cuts more or less. If Titebond is applied to an end grain much or most of it could wick into the end grain leaving little for bonding to the 2nd piece of wood. Double gluing is the application of glue onto bare wood, allowing it to be absorbed (filling the grain) followed by a 2nd application of glue to the "previously glued surface" resulting in a much more consistent and strong bond.

The red line is the glue used for the butt joint.
The purple fillets are of glue and are simply applied / spread with your finger. If you're using Elmer's glue - you can like your fingers - yum!

Now for Zor to tell me that I'm clueless! http://www.rcuniverse.com/forum/js/f...n/drowning.gif Won't be the 1st time nor the last ...

RE: Slow CA
 

pkoury

Did you ask
Please explain double glueing. What were the fillets made of?

Double glueing involves that after a joint has been glued and cured we apply a second application of glue in the corners to create a fillet. The fillet is made of the same glue.

The idea is to increase the binding area of the joint.

As you look at the attached pictures you can easily figure that the binding areas can become 5 times the area of the parts in contact..The added weight of the glue is negligeable but the strength of the joint is considerably increased.

Zor

RE: Slow CA
 

John,

I remember paying you compliments but your last line above bothers me.
I do not remember having said any such thing or similar things to you.

If my memory is failing me in my old age then I apologize.

I have always considered your postings appropriate, informative and well written..

Zor

RE: Slow CA
 

The OP was asking for an opinion on what glue to use. I not only gave my opinion but experience what has worked for me.

I respect your opinion and point of view as well. I enjoy these types of discussions as they help each of us make our own choices on how to build our models.

RE: Slow CA
 

Didn't know there were 'glue divas'. :)

Thanks for painting with a broad brush! :eek:  I can't tell which glue is used by the finished product, and I doubt you could, either. If used properly (like any glue), CA is fine for the entire aircraft. Same goes for AR. If built and covered properly, it's not an issue at all. 

I've been building since the mid-60's, and hopefully my building has improved with each model. I've used and tested almost any glue you can think of.  I've yet to see a bad glue joint cause the loss of a model. To imply that the CA joint won't hold up is preposterous. It may be more brittle in the event of a crash, but I don't build for a crash. I have seen aircraft built with AR rekitted so badly, we had to use a rake to clean it up. If you're a hack, in building or in flying, it shows.

Perhaps 'glue dilettantes' is more..., fitting? [8D]

RE: Slow CA
 

If you are going to join the root ends of each wing panel then no you cannot use CA glue for that you will need 20 or 30 minute epoxy. But if you are just building the wing as in laying and pinning the spar to the building table and then setting the ribs on the spars well this is where you can either use elmers wood glue or CA this is purely for which one you choose to use but either glue is fine. The other builders speak of "brittle glue joints" well I have no idea what they are talking about, yes CA glue goes into the pours of the wood this is how CA "kicks off and cures" and builds the strong joint between the two joined wood pieces. I have a Great Planes Ultra Sport 60 that I built back in 1991 still in my hangar in flying condition and was built from CA medium viscosity for glue joints and thin viscosity for the CA hinges and epoxy for the firewall, wing root and wing joiner and tail feather. I can only suggest that you follow the build manual and follow its "glue type directions" to get you the proper glue for the area of things to be glued. Good Luck. If you like inbox me with a picture of what you are working on and I can help with your glue question.

RE: Slow CA
 

pkoury,

Did my pictures and the drawing by JohnGilmore satisfy you as a proper answer to your question ?

Can you see how the filleting adds little weight while increasing the binding area up to five times or in accordance of how the fillets are made and extended ?

The two pictures I posted of thered piece may have appeared funny to some viewers.
That part is a cover on the nose top with an IC engine that did not use a muffler in the old days.
that part was treated for resistance to the exhaust residues. Some of the glue fillet were colored red to help evaluate the deposits from the exhaust on the glued joints. That part was built in the late 1950s. You can see the date of the picture at its bottom right corner. It was still undamaged at the date of the picture after that model crashed dozens of times.

It is part of my experimental radio control model that used to crash as often as it had a nice landing. The nose of that model never colapsed. It has a shaped steel nose piece backed by hardwood engine mount that goes all the way to be in line with the trailing edge of the wings. That plane weighted 8 (eight) lbs.and has a span of 72 inches. It is still in my hangar.

CA was unknown in those days and the model was all double or triple glued to make fillets everywhere.

I hope this information is useful to new builders.
We ( you ) should do your own evaluation of this technique and disregard any postings made by some fellows that proclaim that CA is as good.

There is no doubt that CA and shrink film is fine while flying if used properly.
Some building instuctions are suggesting CA to back up their claim of a kit that is claimed to be built in only a few hours, so buy it NOW and fly in just a few hours.

It is in a crash that the difference is seen. The more pieces to be picked up, the more chances that you will buy anoher kit. That is good business for the industry.

You are always free to do things your own way. Not all modelers or fliers are rich and can afford to keep buying new planes whethr they are kits, ARF or RTF or BNF or pre-built by others.

Have fun and avoid crashing http://www.rcuniverse.com/forum/js/f...sn/biggrin.gifhttp://www.rcuniverse.com/forum/js/f...sn/biggrin.gifto the best of your ability.

Zor

RE: Slow CA
 

How could it? The OP wanted input as to what kind of glue he should use to laminate a strip of balsa to a strip of hardwood. This lay-up has nothing to do with "double glueing" (or tripple, or quadruple, ad nauseum) or fillets.

In woodworking, the term "double glueing" means applying glue to both surfaces to be bonded instead of just one. Especially important to end-grain to end-grain bonding.

(All, stand-by for a demonstration to what John meant in his post #26... http://www.rcuniverse.com/forum/js/f...used_smile.gif )<br type="_moz" />

RE: Slow CA
 

That's more what I've understood it to be.

I'm no expert. But my Dad was, a fine cabinetmaker. He taught us to double-glue hardwood or dissimilar woods to get better penetration and a stronger bond. Glue and mate the pieces, separate them for an appropriate time (depending on density) anywhere from a minute or two to an hour or more, swipe a couple times with sandpaper then reglue.

RE: Slow CA
 

Note to all readers,

My post #27 was addressed to pkoury and was in response to his question in his post # 25 .

I think most that followed the thread have realized that I mean (meant) a second applicstion of glue to create a proper fillet.

I even explained that in my post #27.

Zor

RE: Slow CA
 

The gift that keeps on giving...<div>
</div><div>;)
</div>

RE: Slow CA
 

</p>

eddieC,</p>

One of my posting is being criticized on semantics about the meaning of "double gluing".
You follow with a posting agreeing with the post attempting to correct my understanding of "double gluing".</p>

Then you explain _ _ _</p>

Glue and mate the pieces, separate them for an appropriate time (depending on density) anywhere from a minute or two to an hour or more, swipe a couple times with sandpaper then reglue.</p>

Is this not a second application of glue after a time lapse ?</p>

It sure appears to me that we can refer to this as a second gluing or "double gluing" as I was using the term which I had explained in my post.</p>

It is sometime very interesting how we can read peoples' reactions in this forum.
It is often reflecting the attitude of who is looking for an opportunity to criticize instead of being helpful and contribute with an explanation as was requested.</p>

JohnGilmore was helpful with his drawing that he posted while I was writing and finding the pictures I posted a few minutes after John.</p>

I will contimue to refer to the process as "double gluing" meaning a second application of glue to assure that all joints have a fillet of glue that increases the binding area.</p>

Zor</p>


P.S.: I do not know the purpose of the followingtext line inEJWash1 posting.
(All, stand-by for a demonstration to what John meant in his post #26... )

End

</p>

RE: Slow CA
 

For a spruce spar, nothing beats good old PVA wood glue. CA doesn't bond to spruce very well. If it's a balsa spar, CA works very well, the glue joint will not fail.

Negligeable for an LT40 maybe, but it's a big deal on a super light performance 3d model or equivalent, especially the small ones where every gram saved counts.

RE: Slow CA
 

I agree, semantics! Sorry if I offended, Zor. Didn't mean to, but I must have missed the 'separate the pieces' part.

There's more than one way to skin a cat, none of these techniques are set in stone.  Don't take these posts personally, either.  It's the Interweb. Have fun! [8D]</p>

RE: Slow CA
 

EXACTLY! Thank you!

The point is that if you don't do it "zor's way", he comes back with some low-brow, classless remark like "avoid crashing to the best of your ability". Being that the OP is building an entry-level model, what a great morale and confidence-booster, eh? NOT!

NO NEED to apologize to a person that would write such a thing!<br type="_moz" />