prole

My Feedback: (3)

So in working on my design project and on the Seniorita I have been finding myself using more and more CA. It is something that I swore I would never do, become one of those Thin CA and 5 minute epoxy guys. I used wood glue and was darn proud of it. you know after all, that patience is a saintly virtue

Really though, I think with all that is going on outside my workshop, 50-55 hours of work, 3 bands, new house and a young lady by my side that my building time is really precious. When I finailly do get a little while that I can spend playing I want to get as much done as possible. I also imagine that this a pretty common thing, it is afterall, this kind of thinking that keeps ARF's flying off the conveyor belts.

the question:

I have learned pretty recently from some very knowledgable fellow VR/CS-ers that aside from regular old water based wood glue, Ambroid style glue is the lightest, followed by CA and finially epoxy. Since I have been using that much more CA I have been trying to compensate by looking for something else to use in area's that require a lot of glue.

I just got a tube o Sig-Ment, would have gotten Ambroid but the store didn;t have it, and just got finished using it for the first time. Seems to work ok, don't know about drying time or sandablity yet but I'm hopeful...

any of you guys have any experience with either of these glues? Just wondered what you thought and if I was wasting my time.

thanks guys

as always,
T

Lynn S

If it's the same Ambroid that they made years ago, I wouldn't use it. I had an old Sterling P-51 that I started building in the '70s. I threw it away about 5 years ago because it was built with Ambroid and was falling apart. I like Elmers.

zoomzoooie

I never liked Ambroid.
I used Lepage's Balsa cement one my small planes when I was a kid. It dried fast and was light too. I never see it anymore. Is it still around?

ZZ

BMatthews

I used Ambroid for years and never had any problem with it. And although they are all gone now I had a couple of models that hung on around the homestead for at least a decade and a half and died a proper warrior's death in the end rather than from any form of leprosy like disintegraton. So I don't know what's up with your experiences. Could it be the climate differences?

And Ambroid and Sigment are probably the most sandable glues you will find. Not rubbery like carpenter's glues and not hard like steel like CA can be. It just sands down like the wood around it without plugging up the paper.

Rendegade

I've always used that stuff to do sheeting for that very reason, mind you in Australia, ambroid is known as Aeroflyte C23.

It's great for areas where you know you're gonna have to sand later, and you don't want that nasty lump of CA to have to sand through.

I love it but I use it sparingly, I don't trust it's structural strength.


It's also great for fixing holes in dope & tissue wings

wild fred

My Feedback: (3)

I use yellow glue on the sticks of my senioritas, and sig-ment for the nose sheeting. usually tack the ribs with thin ca and go over joints w/ yellow glue. (sig bond) sigment is the best for joining sheeting as it sands like balsa. i don't think it is the best for a butt joint, but I built an electric seniorita w/ a magnetic mayhem motor and gear drive entirely with sigment and micafilm covered about 3 years ago, and it is still around; and LIGHT!

having said that, my latest seniorita was built mostly with c.a., as my last one got midaired and I needed to get one in the air fast! it has a norvel 40 on it with barn door ailerons and hovers on the deck! seems to be holding together well, you guys wanna see a pix of it? am gonna reduce the plans by 1/3 and build an 074 one w/ herr floats; when I get caught up!

LouW

I have been using Ambroid for more than 50 years. I have never seen the aging problem described. It is light, strong, sandable, completely fuel and waterproof, and reasonably fast drying. For many years the solvent adhesives, such as Ambroid, were known as "model airplane cement" and were all that were used for balsa construction. Today I use all types of modern adhesives depending on the task at hand, but there is always a tube of Ambroid on my workbench.

jessiej

I recently started restoration of a Thunderbird built around 1958-59 using Ambroid. The silk covering was fragile, but the glue joints are as strong as when built. Having read reports of the short life of Ambroid I tested a few loints to destruction and in each case the joint was stronger than the wood.

The history of Ambroid is quite interesting, by the way. It was initially made by dissolving horn rim glasses in acetone and used in the production of canvas canoes.

jess

ajcoholic

My Feedback: (10)

All I can give in my personal experience..

I start ALL my students on sigment to learn pacience and the value of a good fitting joint. I also buil many of my rubber ff models with sigment, and have a few old (allmost 20 years) plane that are still strongly held together with the "old" type balsa cements.

It is different to work, too much or not enough glue is an issue (either a dry joint or one that wont cure properly if too much is applied) and you need to have a near perfect joint for any strength. We get spoiled with the CA and epoxy gap filling properties....

If time isnt an issue, and the smell doesnt bother you I say go for it.

AJC

tommy s

My Feedback: (55)

I have used Ambroid for many years and never had any problems with it. I prefer
it to CA if only it dried a little faster. Time is always a problem.

tommy s

fritzke

My Feedback: (1)

Here is a link to some Ambroid lore via the MAAC website:
[link=http://www.maac.ca/committees/reports/archives_2003-02.html]MAAC Story on Ambroids History[/link]
http://www.maac.ca/committees/report...s_2003-02.html
Dave

BMatthews

Something that I just remembered for high strength Ambroid joints. It was always recomended that high stress joints should be double glued. That is, the surfaces were sealed with a thin coat of glue wiped on and left to dry. Then a second smear is added and the joint closed while it's wet. Being a solvent based glue the second coat would soften and bond to the new coating. For single coated joints the glue was so thin that perhaps the problem was that it sqeezed too much out.

I often used a modified version where I'd push the two parts together lightly so there was still a small space. After about 5 or 6 seconds I would push then together for the final joint. I reasoned that this gave the glue time to penetrate before being squeezed out. It seemed to work for me.

wild fred

My Feedback: (3)

just noticed; if you look at my contest entry pics in this forum, there is a bottle of sigment on the table; I use it to glue down the l.e. sheet to the ribs. how's that for a testimonial?

gcb

Bruce revealed the secret...double gluing joints and good fits.

Cement has a lot of solvent and it is easy to leave a weak joint if you do not let the first coat penetrate.

George

ajcoholic

My Feedback: (10)

Yes, I often tell my student to apply a smear of cement to the wood (especially end grain joints, as in constructing small fuselages from sticks and stringers) and then a little dab before pinning together.

AJC

prole

My Feedback: (3)

Thanks for all the good advice guys, one thing that I did start doing right from the beginning is doing the double coats, this is taken right from the Sig-ment bottle-

"For best results apply a thin coat of Sig-Ment to each surface to be glued. Let dry for 2 or 3 minutes, then apply a second coat and press parts together"

no indication given as to how long to keep pinned for a complete bond to set up, I have been leaving things for at least an hour before going any further.

One thing that I have noted since I have been using it on the Seniorita wing is that if for whatever reason the bond is compromised, either from being to aggressive with it to soon or from a bad joint, just setting it back in place and hoping for it to re-set has been pretty much wholely unsuccessful. What I have had to do is either open the joint wide enough to get a little more cement in or if possibe to pull the pieces apart and start again.

Most of this has come from trying to see how long it took to set up and what the biggest advantage this holds over CA is that once a pice of wood is soaked with CA it is really hard to get a good bond once the CA wont absorb anymore. The the Sig-ment, if you mess up and have to re-glue something, putting more glue on it seems to re-activate the old glue.

I guess this is due to

Wild Fred- 2 things, first I would love to see some pics of your Seniorita's and when you get the 074 version together I'll pay for a set of the plans. When I started mine I made sopies of all the plans and was excited to be able to build more as needed until I finished glueing all the ribs in place and I realized I didnt trace any of the ribs [DOH[:@]!!!!] oh well, guess I'll be asking for help on that one...

2nd - tell me more about the process in which you tack the ribs, you say thin CA then wood glue. It says in the directions that anywhere you use thin CA to go over with Med or Thik CA to beef up the joints. Does that add less weight then just doing it with Med CA once? What about doing it with thin CA and then going over it with the Solvent type glues?

thanks guys

t

wild fred

My Feedback: (3)

well, the solvent based glues probably won't absorb into the wood once tacked with c.a.; but I usually use the thin c.a. just to hold stuff, then when done I take a 1/8x1/4 stick, sand the end round, put a puddle of glue on the wax paper and use the stick to fillet the joints. medium c.a. does the same thing, but with a weight penalty as no evaporation. I will try to get a pic of my new seniorita with the norvel 40 tomorrow. flew it today at lake wales fly in, it is funny the reaction you get from people when you hover a trainer! I posted a pic of my last micafilm covered one with the os 52 hovering a while back, it is in here somewhere! I also posted a pic of the saito 72 powered one on floats in the seaplane forum about a year ago. haven't got the plans copied yet, but will send you a set when I do. if you got yours, just take them to kinko's and tell them to make them 67% size. and keep plugging away on the seniorita, it is worth it!

BMatthews

Guys, filleting joints is a great way to add very little strength but lots of needless weight. If the glue isn't in the contact point between the two parts in a very thin layer then it's only doing a small fraction of what it is capable of. The only exception to this is epoxy since it forms non shrinking fillets that encase the wood. Particularly spotting joints with CA and then dabbing carpenter's glue on the outside does very little for strength. Carpenter's glue of all of them is the WORST glue for anything other than the actual bit that is in the joint itself. And it doesn't soak into tight cracks worth a darn

The best advice is to use one type of glue per joint and use it as it was intended. You'll get better results that way and less weight buildup.

This isn't just me either. I've read a fair number of articles in wood working magazines over the years about this important area. Reams of research material are done on wood glue joints and the bottom line is that almost all glues work best on wood when there is only just enough to fill the joint. Carpenter's glue in particular shows marked weakening when the joint is more than 4 or 5 thousandths thick. Of course this is only an issue for hardwoods but it points the way to logic of using glue as it was intended. As for filleting thin CA joints with thick or medium the same thing applies. I can't see you gaining much, if any, strength over a well done thin CA joint but I can see the weight building up. Not to mention the time required to fillet all the joints.

prole

My Feedback: (3)

That makes sense Bruce - but I can see both sides of it for sure.

As someone who buys Wood Glue by the gallon, epoxy by the quart and CA by the pint for work I do a lot of glueing, and consequently a good bit of experimenting with glue. With out a doubt, Wood GLue is great for flat joints and butt joints when you have two surfaces that fit together well and can be clamped (or pinned) for at least and hour. Really, you can't beat it under those circumstances. It's light, super aesy to clean up and sand.

Where my confusion comes in is that I thought the way that you used Thin and Med CA was to get a tight fit and put a drop over the joint with the pieces pressed firmly together. With Thik CA you do it more conventionally, put a drop down then join the pieces. Now with thin especially, if there is any space then the joint is pretty much worthless, but if you get the parts to stick together with the thin, then drop some Med over the gaps I have found that you get a pretty solid joint. Is that redundant? SHould I only use the Med, or the thin for that matter

Now listen, I am NO EXPERT, that is why I have this thread going. I do know that if you use the right glue for the job then you are more likely to get a good joint then just gobbing on the wrong glue. I want to know how you guys do this.

I guess what I am asking is what is the correct way to use Thin CA and how does the application differ from Thin to Med to Thick?


thanks guys, and Wild Fred, thanks for the hints on finding the pics, I'll try to hunt them out tonight...

timothy

ajcoholic

My Feedback: (10)

As a professional woodworker, I agree with Bruce. Most glues (exceptions are 100% solids adhesives like certain epoxies and a few others, resorcinal for instance) are NOT designed to fill gaps. The worst of all has to be any of the modern PVA or aliphatic wood glues. The joints HAVE to be tight fitting to have proper bond strength.

Sigment/Ambroid or Testors balsa cement, etc - these too form weak bonds if any, unless you have a tight fit between the wood parts.

Thats one main reason I teach my students using Sigment. After a few times that they pull off a fin or stab, or a fuse side off the plans and it fall apart in their hands - they soon realise that I mean tight joints need to be TIGHT! My favourite saying is "hey, that balsa looks like you chewed it to length with your teeth!" Heh heh... a good sharp #11 and a razorsaw does wonders, as does sanding a joint to fit. Thats my preferred method with stick stock.

AJC

BMatthews

I do it that way all the time but ONLY with thin CA. Even medium does not have the wicking power that thin has. You can see this for yourself. Butt up two peices of really good fitting wood at a right angle and then put a drop of thin on the joint at one end. Watch it run along and soak into the joint like magic. Do the same thing with medium and it stalls pretty quickly into a little bubble of glue mostly on the outside. Breaking the joint apart after curing should show the relative penetrations and why I suggest you only use the thin stuff for the dry fit method. For what it's worth do the same thing with a couple of new bits of wood but smear carpenter's glue the length of the joint and let it dry without "working it in" with any flex of the parts. I think you'll find the wicking action of the relatively high solids content aliphatic glue is minimal as well.

No it's not redundant. It's a bandaid I also often use to get away with either a "mistake" that isn't that important, repairs where the fit isn't perfect or by design where I need to fill a gap. In a gap situation you will get more penetration out of the medium than the thick with almost as good a gap filling effect. Note that I do NOT use thick CA. If the gap is that large that I need that sort of filling power then I will stuff slivers of wood or baking soda into the joint to act as filler. Yes the thick works in that capacity but I don't find I need it enough to justify it aging unused on my shelf. SO I pack and glue instead for the rare times I need it.

Often I understand that the longer open working time of the thick glue can let you do things like sheeting but in that case the need for speed is on my mind and I go back to aliphatic so I can plan the work better. But if it works for any of you then carry on. There's many roads to Rome after all and they all get there in fine form.

CA glue is a different case from the solvent or aliphatic glues as AJ already suggested. It's a thin liquid but it polymerizes into some tough plastic with little or no shrinkage. In that way it can be considered along with the epoxies and other non shrinking glues. But the thin formula does demand good fitting joints. For my own work I like to put the effort in up front. Typically for wings I block sand the ribs, cut the spar notches for a snug push in fit and notch the trailing edges about 3/32 to 1/8 to accept a push in fit for my overlength ribs (or 1/16 for my free flight models). Doing it this way lets me actually dry assemble my wings on the board and then run around adding little drops of thin that wick into the joints like a cockroach when the lights go on. In effect I prefer to put my time in at the front end to speed up the back end. I also find it's more rewarding to me that way. No slagging of any work methods intended in any way, those roads to Rome and all that, it's just how I like to do my work. But we ARE all human and for times when the planning doesn't work out I still reach for my bottle of medium and the box of baking soda.

So for anyone that isn't sure about how their glueing methods work out cut up some 1/8 x 1 and spend a bit of time making simple end grain to side grain T joints and glueing in every way possible. If you use firm wood a proper glue joint should always pull out a divot of wood from the side grain portion at the top of the T when you break test the joint. Be sure to include a version where you deliberatley leave some gapping and fill it with the medium after tacking with the thin. I think you'll find it works fine but the glue IS heavier than the wood in that case. With the aliphatic I think you'll find the outer fillet skin just peels back like rubber tape with little assistance to the joint. But a proper aliphatic joint will easily pull out the divot of wood.

It'll all be very educational in any event.

gcb

To reemphasize a couple of points Bruce made:

If you can't make close-fitting joints or are assembling a kit with less than perfect die cutting, use medium CA instead of thin. If you have only thin or the joints are really bad, fill the gap with baking soda before applying CA.
(HINT: DON'T touch the tip on the CA bottle to the baking soda, drop the CA on.)

When CA (CyA at that time) first became available to the modeling public (Hot Stuff), only thin was available so some of us used baking soda as gap fillers AND fillets (HEAVY fillets ).

George

wild fred

My Feedback: (3)

ha! haven't used baking soda since the early 80's! guess my joints are TIGHT now! many ways to do stuff. as long as it doesn't break on impact. mine do not.

wild fred

My Feedback: (3)

by the way, I am not a professional woodworker. I did my time in a cabinet shop, built houses, and was a professional model builder for years. now I putter in the garage.

I don't fillet with yellow glue for strength. I do it for impact/vibration dampening. as bruce says, thin ca will wick into joints. It has good tensile strength. however, ca has crappy shear strength. I remember reading an article in m.a. about 15 years ago how a man tested it for tensile strength in labs, then they seperated the test blocks with a sharp rap... Not ideal for models, as they get sharp raps from time to time! on my sheeted wing designs I will use thin and medium, as the contact area is large. but a seniorita is open structure. any torsional load will pop the rib/spar c.a joints loose if it hits on a wingtip or something. If thin c.a. is filleted with a little yellow glue, the idea is to have it flex less than the balsa, keeping the joint intact.

Again, that's just what works for me, and a few of my reasons for doing what I do, learned from 28 years in r/c and a few years more in c/l and rubber before that; your experience may and probably will differ; but when my last seniorita got midaired and hit from 100 feet with no tail and smashed and broke most of the ribs... except around my glue joints...hey, gotta be something to that. ever see lite ply fuselages shatter on impact? That's why I use balsa. Great shock absorbing qualities. but that's another story...

so, you guys do it the way you want. I'll do it the way I want. and we'll all have fun!