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Author Topic: Ironing glue joints  (Read 1327 times)

Offline Bootlegger

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Ironing glue joints
« on: December 09, 2018, 04:19:41 PM »

  Some years ago I read where you could iron two sheets of balsa in lamanition and they would stay together.
  Can some one remind exactly how this is done?  Thanks
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Offline Dan McEntee

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Re: Ironing glue joints
« Reply #1 on: December 09, 2018, 06:01:18 PM »
  You need to apply glue first to one sheet, then let it dry. When joining the two pieces is when the iron is applied. I tried this with several airplanes on D-tube wings going back to my R/C sailplane days. Once you get to the point where you are ready to apply the leading edge sheeting, you apply glue,( usually aliphatic resin or carpenters wood glue,) to the ribs, spar and leading edge, and let it dry. Set the sheeting in place along the spar making sure it's even, then tack it in a couple of places with the hot iron. I think I just used a monokote iron. then run the iron along the spar slowly to set it in place. Then start with wrapping the sheeting along  the ribs down to the leading edge. This part goes a bit easier if you preshape the wood a bit first. When you get to the leading edge, finish that off. Then sand as required. I never had a problem with a wing done this way. BUT!!! It only works on the first try. If something doesn't go correctly, you have some work to do to fix it. I don't know how it would work on a large area sheet lamination, as far as warping goes.
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Offline Tim Wescott

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Re: Ironing glue joints
« Reply #2 on: December 09, 2018, 07:19:42 PM »
Note that it must be a heat-activated glue, and the temperature at which it activates needs to be well below the temperature at which the wood will scorch.  So not epoxy, CA or (I'm pretty sure) Ambroid.  Aliphatic resin (including carpenter's glue) is the only one that I know of that works, but my experience with this stuff is not broad.
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Offline EddyR

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Re: Ironing glue joints
« Reply #3 on: December 10, 2018, 07:12:22 AM »
I also did leading edge sheeting that method many years ago. Also laminated wing tips.
Ed
Locust NC 40 miles from the Huntersville field

Offline john e. holliday

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Re: Ironing glue joints
« Reply #4 on: December 10, 2018, 09:27:27 AM »
Did it with Elmer's White Glue several times.   As stated if it didn't stick first time you are out of luck.  Max thickness on sheet balsa was 1/16.  Don't try it on foam. H^^
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Offline FLOYD CARTER

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Re: Ironing glue joints
« Reply #5 on: December 10, 2018, 11:14:30 AM »
From my experience, any time you apply heat to balsa, it warps. Is this what you want?
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Offline Bootlegger

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Re: Ironing glue joints
« Reply #6 on: December 10, 2018, 01:15:35 PM »

  Floyd, this is to bond them together more quickly  than waiting for them glue together when just lamaninting  them..
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Offline Bootlegger

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Re: Ironing glue joints
« Reply #7 on: December 11, 2018, 06:46:16 AM »

   Fellowa I sure do appreciate all the help, look forward to trying this method..
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Offline john e. holliday

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Re: Ironing glue joints
« Reply #8 on: December 11, 2018, 01:36:02 PM »
I would never do this for laminations. D>K
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Offline Steve Helmick

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Re: Ironing glue joints
« Reply #9 on: December 11, 2018, 02:46:35 PM »
Seems like a good use for epoxy. However, with thicker pieces, or even thin pieces where you want a flat result of maybe 3 or more lams, consider stacking the lams (aliphatic glued on both sides, pre-dried) between two metal plates, and bake them in the oven at low heat. Ours goes down to 170 degrees, which should be more than adequate.

This might be a good way to laminate multiple layers of balsa or even plywood. Most ovens wouldn't be big enough for a bigger profile fuselage, but a Ringmaster Jr. or Jr. Flite Streak should fit. Don't forget the metal plates need to be thick, flat, and heavy. And I have no idea how long it would take for the heat to soak into the stack, so that'd take some experimentation. A meat thermometer might be useful...or not. There are some high-tech devices out there for grilling, BBQ and smokers...Blueteeth and all that stuff.  ;) Steve
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Offline EddyR

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Re: Ironing glue joints
« Reply #10 on: December 12, 2018, 09:11:50 AM »
One thing I remember is it is important that both surfaces touch. It will not do gaps.
I built two Nobles that way. The leading edge was the hardest part. it was fast and no pins needed.
Ed
Locust NC 40 miles from the Huntersville field

Offline L0U CRANE

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Re: Ironing glue joints
« Reply #11 on: December 15, 2018, 01:21:36 AM »
It's been many years since I first mentioned a technique I've used with aliphatic resin glues - like Elmer's (yellow) Carpenters' glue.

The key principle involved is that aliphatics resolve slowly to their full bonded strength. Heat accelerates most chemical reactions. Heating an aliphatic-bonded joint line does two things: it 'boils off' any remaining water (solvent) slowing the chemical reaction, AND it accelerates that reaction.

The prep process has been described well already, but I'd add that joint lines need not be full-cure dried, only "dry to the touch."

Say, for LE sheeting...The structure MUST be jigged solidly into the final desired alignment! Once the glue seam is triggered  to final strength it will take replacement or major surgery to remove a warp!

A Monokote-type  iron is a natural for this, and sheet balsa up to 3/32" can be bonded. The residual water will hiss of as it kicks, even if the joint line seems very dried - for say up to a half hour after 'wetting' with  a thin line of full strength or up to 50/50 water thinned aliphatic.

You WILL hear a slight hiss as it kicks. Then (seems to me, anyway) it is bonded as well as a week's waiting would make it.

I have not tried flat sheet laminations, and doubt they would work as well. The heat needed to 'trigger' the bond would most likely warp the sheet surfaces.

Several models done this way. They stayed 'true' and withstood come pretty challenging "landings."
\BEST\LOU


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