Do your doublers slide...?

Epoxying doublers to fuselage sides has always given me fits. No matter how I weight'em down or clamp'em or vise'em, they slide out of position. So I tried something today and it worked. I carefully aligned the doubler over the fuse (just like Steve says to do in the directions), then drilled three 1/8th holes through both. Applied the epoxy, aligned once again, then pushed 1/8th hardwood dowels through the holes. (On a profile, you could do both doublers and the fuse at the same time). I cut the ends off flush with a zona saw and weighted everything down with no fear of the darn things sliding out of position. Probably not that big a deal, but I like it! best regards, dale g

Sounds to me like you are using too much epoxy. You really do not need much glue on the surfaces to get good adheasion. What I do is have a wooden trowl. It is a piece of 1/4" plywood about 6"x4" with about 1/32" deep notches cut in it about 1/4" apart. I spread the epoxy on like you are undoubtably doing and then scrape the surface removing most of the glue. You will be leaving ribs of glue on the surface and just wetting the rest. You can now weight the piece down and let dry. I would recommend putting the glue on the plywood doubler and then scraping 90 degrees to the thrust line. There is less soaking in that way.

I scrape it all off with a couple of playing cards, Matt. Maybe gremlins get into my basement and move things around? I have left a lot of epoxy on the Carrier planes and they did have a tendency to move when pressure applied with a c-clamp, but it's really a bother when I leave something to cure overnite and it's dried out of position next morning. This does work. Thanks, dale g

>Epoxying doublers to fuselage sides has always given me
>fits. No matter how I weight'em down or clamp'em or vise'em,
>they slide out of position. So I tried something today and
>it worked. I carefully aligned the doubler over the fuse
>(just like Steve says to do in the directions), then drilled
>three 1/8th holes through both. Applied the epoxy, aligned
>once again, then pushed 1/8th hardwood dowels through the
>holes. (On a profile, you could do both doublers and the
>fuse at the same time). I cut the ends off flush with a zona
>saw and weighted everything down with no fear of the darn
>things sliding out of position. Probably not that big a
>deal, but I like it! best regards, dale g

I glue the doubler material on BEFORE I cut out the fuse sides. The alignment is not critical at all if you do that.

You might try an old furniture makers trick: place a few grains of sand on each end of the part after you spread out the adhesive. It generally gives enough bite to prevent sliding. And it's cheap!

I have had this problem. A lot. I found that placing a sheet of carbon veil between the pieces seems to help.

>You might try an old furniture makers trick: place a few
>grains of sand on each end of the part after you spread out
>the adhesive. It generally gives enough bite to prevent
>sliding. And it's cheap!
>
>Dave
>LA_Flyer

I like the furniture makers trick I will try this next time.

I built one airplane by clamping the doublers in place first then using Thin CA glue to glue them on. It soaked up 1/2 bottle of CA glue but that is probably much lighter weight than a tablespoon of epoxy glue. That was 3 years ago and the double still seems to be glued on tight.

I wonder if UHP could pre-glue the doublers and then have Kyle laser cut it? Go too far with this and you know what it could lead up to...It took me only three tries this time to get two LG wires bent, so I'm on a roll. Best regards, dale g

I use the same procedure as Brett when I can get away with it.
When alignment is critical, I drill and pin the doubler(s) with short lengths of toothpick.
Derek Moran

Hi Brett Well, I do exactly as you do, which is fine if we are scratch building. If one is building from one of these great lazer cut kits which sounds like what Dale is doing, then the alignment of the doublers becomes very critical and some method must be used to insure that the parts do not slip. I bet you had that figured out!! Cheers, Roy D

Hi Dale,
A drop of CA in a couple places will stop the sliding. Doesn't take much, just a tack.
Bill <><

I've used the drop of CA, but I like the dowel idea.

>I've used the drop of CA, but I like the dowel idea.
>
>Jim

Toothpicks do work a treat for this. Can't remember where I read it, but I've used it several times now, always with excellent results.

Tim

>Epoxying doublers to fuselage sides has always given me
>fits. No matter how I weight'em down or clamp'em or vise'em,
>they slide out of position. So I tried something today and
>it worked. I carefully aligned the doubler over the fuse
>(just like Steve says to do in the directions), then drilled
>three 1/8th holes through both. Applied the epoxy, aligned
>once again, then pushed 1/8th hardwood dowels through the
>holes. (On a profile, you could do both doublers and the
>fuse at the same time). I cut the ends off flush with a zona
>saw and weighted everything down with no fear of the darn
>things sliding out of position. Probably not that big a
>deal, but I like it! best regards, dale g

That is what I do, but I use bigger dowels (3/8)and try to line them up with existing hardpoints like the LG mount or the tank mount. I cut them off after the glue sets up.

Skip the epoxy glue all together and use Pro Bond or Gorilla glue,
I really have found that it is a great glue. If it can hold the landing gear blocks in my 45 pound RC Corsair, it should have no problems with the fuselage doublers or any other part of the plane.
Epoxy is just plain thick. This can be applied very thin, and it does expand when it cures. Try it you will like it.

Dale,
There's plenty of good advice above but I wonder if you are keying both your surfaces correctly?
If you cross hatch the ply with a piece of sharp hacksaw blade (or similar) and cross hatch the balsa with your modelling saw you'll end up with two furry surfaces which will soak up a surprising amount of epoxy and should not creep when clamped (or weighted) together.
This way (because of all the minute hills and hollows) the area being glued is effectively much greater than un-keyed surfaces and will be a much stronger bond.
Cheers, Tim

>Epoxying doublers to fuselage sides has always given me
>fits. No matter how I weight'em down or clamp'em or vise'em,
>they slide out of position.

Try thin CA around the edges in several places. This will secure the doubler for weighting.

I also recommend PU glue over epoxy for laminating. I bought some Gorilla glue as replacement for my Titebond PU glue. It seems to be slightly thicker, but works the same and is available at Home Depot.

What works as well as the grains of sand, is a just a pinch of sawdust (which is usually abundant...). I use hardwood sawdust from a saw rather than balsa dust from sanding.

I think I first read about that trick from the tips section of a MAN from the 60's.

I also key with dowels (or similar) a lot, and as mentioned, try to double their use by placing them strategically and using them as mounting or anti-crush points for tanks, gear, whatever.

Aliphetic resins (yellow glue) are famous for creep during setup as well.

Wishing everyone a happy and safe Thanksgiving,

Tools

I do the same as Brett, and have done the Cya tacking too. However, when the doublers are already cut out I've used the plastic capped straight pins to locate the doublers and placed the weights between them. These pins are sold by Campbell's Custom Kits and are hard steel and of a very small diameter. They are extremely sharp and with the large plastic head they are easy to push through even 1/8 birch ply with only your thumb. I like this better then the dowels or tooth picks because the pin hole virtually disappears after sanding, but I've had dowels read through the finish after several months.

What I do is apply the glue, locate the doubler, then shoot it with staples, in about 4 places, then weigh it down. After it is set, pull the staples out and fill the holes.

Dale,
We need pictures!!!!

Thanks
Paul

Good idea, Paul. Next plane you and the boys build, take some pictures of the doublers being pinned and post'em here! I'm kinda' leaning toward the stapler idea, myself. You all have a great Holiday, matter of fact, while I'm at it- a great Holiday to EVERYBODY who picks up the handle! dg