wrstew

My Feedback: (30)

For what it is worth: in the past two years that I have been on these forums searching out methods and techniques in building airframes, I have on numerous occasions found people who firmly believe that the new poly glues are the only way to go. After destruction testing, both bench and real life, the use of polyurethane glues are purported to be good. The trick is (same as with epoxy) to spread it to a point that it is not apparent, spritz a mist of water airborne, wave the opposing piece thru the airborne mist, assemble, vac bag or weight, the clamping forces are dependent on the means available. Both bagging and weighting have been proven, the differences between the two in the final outcome are unproven. I have epoxy available because of the industry that I earn an income uses it, otherwise I as a beginner would probably use poly. Besides, if both ways work, what's the difference to the wing>? We are only gluing balsa to it, not building composite wings. In the case of a full blown composite, epoxy is the way to go. I order polyester resin by the barrel, and wouldn't use it though it is free, because of the weight to strength ratio involved in a composite lay up. But on 424 wings, even 428 with spars or carbon fiber reinforcements I believe either is the best use of available materials as an adhesive that is available at this point in time. I've found these disagreements on a number of threads, and firmly believe that if a wing is on a flat base the means of holding it there does not matter- if you can, the vacuum bag is most assuredly the easiest and time honored current method, but good old weight will work if ya gots ta. With all of the knowledge of the people building these, I would think that a plan A as well as a plan B would both be viable to the guy who is just getting involved and does not have the luxury of a precision bench and a vac set up. A flat garage floor is regularly used in these pages, seems to work great. Whether it is a ton or a couple of hundred pounds of pavers, weight holds things flat while the cure is happening, that is all. If I'm wrong in any of these assumptions, please correct me......once again these principles are what I have read on these information exchanges, and I am capable of misunderstanding. Really like to do it over coffee, but any response either way is appreciated. Yer most humble exchanger, Randy

HighPlains

My Feedback: (1)

Are they really flat?

I've seen my share of destruction testing. 3M 465 Acrylic Tape held the skins to the cores best of all, but it didn't matter after the test. Epoxy shears the little beads of foam about as well.

daven

My Feedback: (1)

In many cases, garage floors are not flat. Otherwise, I agree with everything else in your post.

I've had good luck with weight versus vacumn, and epoxy vs. gorilla glue.

It all works.

dhal22

i have tested both and found that the poly had expanded further into the foam than the epoxy. plus no mixing with poly and more importantly no incorrect mixing. i hate soft epoxy.

Kevin Matney

My Feedback: (1)

Try Skin It Epoxy [link=http://matneymodels.com/accy.html]Skin It Epoxy[/link]

dhal22

i like the forgiving comment on the epoxy kevin. i hate soft set epoxy.

sahartman21

So how do you apply Gorilla Glue?

I am familiar with using a squeegee with epoxy. I use two 1 ounce Dixie cups of glue.

daven

My Feedback: (1)

I've found it goes down thinner and spreads easier if you warm up the bottle first by soaking it in a bucket of hot water for a while before using.

I use a squirt bottle and mist the foam cores with water, but not the balsa. In a drier area I would probably mist both.

drizzle the glue on the sheeting and scrape down to a very thin, nearly dry surface. If your adding any CF under the sheet, apply that to the balsa, and then add a little more glue on top.

attach the sheeting to the foam and toss into the bag. If you want, you do not need to edge glue your balsa sheets if you are using multiple widths. Just tape them good at the seam and the gorilla glue will penetrate and attach the sheets while drying.

I've used both methods, both work, some prefer poly, others epoxy. With either, put down some newspaper and wear gloves, both can be messy.