waagbuck

My Feedback: (1)

I'm in the process of soldering the cabanes and interplane struts on my 1/4 scale EAA Bipe (the Balsa USA kit). The cabanes and struts both extend through balsa into the structure of the plane. I'm using a torch to get enough heat to apply the solder, but I'm worried about the effects of the heat on the balsa and plywood structure. I don't imagine balsa would fare well when exposed to a blow torch (or even metal hot enough to melt silver bearing solder). The kit instructions say to use a heavy piece of paper to protect the wood, but that just doesn't seem like it would cut it. This wasn't really a problem for the landing gear because the solder joints are far enough away from the balsa that I could keep it separated.

I tried making a barrier out of an aluminum can, but that's a real pain, and I was wondering whether somebody might have a better way to do this. Any suggestions?

By the way, this is my first time soldering anything other than small electrical wires and an occasional clevis/pushrod connection. I tried various soldering irons and guns with various power ratings -- all without much luck. The little propane torch was the only thing that would heat the metal enough to melt the solder.

LSP972

My Feedback: (13)

I'm not familiar with the construction of that model, but the only sure way to protect the balsa is to fabricate a jig and solder the fittings away from the model. Dunno if you have that option; if not, sorry, I don't know what to tell you.

Deadeye

How about covering the area with plastic, and using a wet rag?

papermache

My Feedback: (35)

waagbuck,
I had a similar problem on my BUSA Nieuport 28. I used a torch on the cabanes, but they had a jig set up for that and I wasn't too worried about burning it up. The interplane struts had to be soldered in place. I ended up using a piece of thin gasketing material I got from work instead of paper to protect the frame. I also used a soldering iron instead of a torch. Yes, it took FOREVER to heat up enough, but in the end I got a very good job out of it. Just go slow and take your time. Good luck and give me a call if you need some more help.

papermache

Mindwarp

The thick paper should protect from indirect heating on the balsa really well. It can also be lightly sprayed with water if you want to increase the effectiveness. If you're worried about head conduction through the cabanes into the balsa then you can clamp a large metal clamp or pair of pliers onto the cabane strut just before it enters the balsa; It'll act as a heat sink and, although won't prevent the heat from conducting down to the wood it will at least give you more time before it reaches the point at which you need to start worrying.

Cheers,
Neil.

RCKen

My Feedback: (9)

Mindwarp hit the nail right on the head. A metal clamp or a vise-grip pliers work great, clamp them as close to the fuselage as you can. This will act as a heat sink and keep the heat away from the wood. If you are worried about solder getting on the wood, get a small sponge, wet it, cut a slit in it and slip it over the wire to act as a shield for anything running down the wire.

Hope this helps.

waagbuck

My Feedback: (1)

These are great comments, and very quick! Thanks for the help. I think will try wetting the balsa and plywood and the paper barrier to see if that works. Perhaps I'll revisit the soldering iron.

The jig is a good idea, but I'm going to rule that out for now because I don't really have a practical way of creating a jig exactly to the dimensions I need. The wings are not in the same vertical or horizontal plane, and my ability to measure things in three dimensions is rudimentary at best.

The heat sink is a good idea too, but not very practical in this application because of the design. The wing attachment points consist of steel landing gear straps that are soldered to the interplane struts as they sit in position on the wing. If i attached a heat sink between the strut and the wing, the strap would be out of place and could not easily be soldered in the right place.

The instructions do suggest that you flip the plane over before trying to solder the joints on the top wing. I suppose this will help somewhat with controlling the heat -- because heat rises, less heat would flow down from the irorn or the torch to the structure when the wing is below the solder joint.

waagbuck

My Feedback: (1)

I finished all the soldering on the interplane struts without too much burned wood. I wet the balsa in the area where the heat would be applied, then installed a layer of paper between the solder joint and the wood, and wet that too. Seemed to work fine.