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Carbon spars plus balsa wing ribs- best adhesive?


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Cyno will glue to any wood in a flash and you will never be able to break the glue joint so make sure it's definitely in the right place because a second later you won't move it, if you are gluing in say a dowel to take a screw into a carbon tube you need to get it into the tuber real quick and in one smoot motion, the bond is so strong I wouldn't even consider using anything else, if you can glue a couple of spare bits together first and you will see what I mean.

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That would do it, Mick Reeves recommends this to stick his epoxy glass skins. And once stuck, you can use them as a wood chopper. The thin cyano would also be good if well fitted. A tight hole, cuts deeper than removed material, would do the job.

 

as in position it, wick the glue in. Phillip is right, get it in position, glue it. Not the other way round. 

Edited by Don Fry
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If the spar and ribs are a snug fit (and in my experience most of the engineered German kits are very precise), then slide everything in place, pin everything down over the (plastic-covered) plan in their exact positions, then zap each joint in turn with thin CA, which will wick right through.

 

A mistake with CA can always be rectified later with CA de-bonder, but this won't be likely if you follow the above sequence.

 

I almost never use medium CA these days, and only use epoxy for high-strength areas (e.g. wing-root joiner tubes or ballast tubes) where gap-filling extra strength is needed.

 

PS - just seen your reply as I was typing mine - go for it!  What's the model by the way?

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Chris, that looks ideal for the job!  There is in fact a downloadable English version of the instructions from their website:

 

http://hoellein.com/Anleitung/gruener-cnc/Introduction-E.pdf

 

I've got a slightly smaller 2.54m FXj bought second-hand.  It has barely been flown, but I need to recover it (the builder used Oratex which is unnecessarily heavy for a thermal model!) and convert to electric-launch with a Hacker A10-7L.

 

Enjoy the build!

 

Jon

 

Edited by Jonathan M
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I have an Introduction kit that I hope to have ready for next spring/summer & have been following a couple of build threads in RCG. One piece of advice that seems a good idea to me is to cyano several turns of kevlar thread around the spars close to each last rib to reinforce the tube ends against splitting.  

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Good point John.  The servo tray in the nose of my Auri DLG came loose early on after a particularly hard landing because I'd omitted to degrease that area inside the carbon fuselage.  With the old CA cleaned off and the whole area roughened slightly, and an extra shoulder of epoxy after CA'ing the tray back in place, it is now fit for... future pilot-error!

 

BUT I wouldn't worry overly about your spar/rib joints.  Yes degrease the carbon tube before sliding it in, but that'll be more than enough.

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