Soldering piano wire for UC legs

[Eifion Herbert]

Putting together some 8swg undercariage legs for my latest project, and the little electric soldering iron I use for electronic bits isn't cutting the mustard for the size of the joint I'm making. I notice butane torches are availabe for much less money than higher wattage soldering irons. Question is, will using something like this on the UC legs do something to the metal and make it brittle, or will I be OK if I'm careful? I don't really want to spend out on a bigger soldering iron that I'll hardly ever use.

[kc]

It is well worth reading Steve's advice on soldering U/C on his "Dave Hurrell BE2 "build blog here on Modelflying.............a masterclass on construction and very interesting comments on butane gas for silver soldering. In particular the use of breeze blocks to form a hearth to retain heat.

I recently bought a cheap 60 watt iron after reading comments that older irons are lower temperature than that needed for leadfree solder. But you can still get lead solder from places like The Component Shop. So indoors I use the electric iron or outdoors a tiny butane torch which refills from cigarette lighter fuel.

[SDF]

You could solder it with the butane torch but it would be very difficult to ensure the wire is not over heated and its temper lost. The wire won't go brittle it will go soft. Personally I would spend a little more on an electric iron they are not really that expensive.

[Malcolm Fisher]

A small butane torch can be OK for soldering piano wire. The most important part is getting the wire scrupulously clean and then keeping fingers away from where the solder is to run. For these items I use Baker's Fluid flux for preference or the sort of flux used by plumbers for soldered pipe joints. All flux residue must be washed off when the joint is finished.

In a recent article in RCM&E, Brian Winch stated that it is impossible to get a good silder joint when using a flame. I haven't had any difficulty and have been doing it for years. It was standard practice when "wiping" joints in lead pipes.

If you only heat enough to get the soft solder to melt, you won't do any damage to the temper of the piano wire. Temperatures high enough for silver soldering will make the wire soft and it can't be retempered after that process.

HTH, Malcolm

[Joe Beavis]

Just in passing - the smaller size of brulle torch sold in kitchen shops is brilliant for little soldering and brazing jobs, even though it is no good for brulleing (I don't know how to do accents). For that we use the full blow lamp!

JB

[crispin church]

i got that torch its not good

[Steve Hargreaves - Moderator]

Agree with the others....with a small gas torch its is very easy to overheat the job & then the solder will not work properly OR you'll destroy the temper of the wire. It can be done but its a bit tricky.

You can get a pretty large iron 60-70watts quite cheaply these days & these are more controllable.

I agree with Joe too the little "Cooks Torches" are great for modelling use. You can even weld aluminium with them!!!

[Joe Beavis]

Crispin,

Was the torch defective - it might be useful to know , so that others can avoid it - or did you just not like the method?

JB

[Eifion Herbert]

I've ordered the torch, I'll post back when it arrives and I've seen how it does. Very intersing read on the BE2 build blog. But now I'm wondering, if the temperatures for silver soldering will remove the temper from piano wire, where would we use it? The main bits that we solder are UC legs, or various other fixings that are meant to take some amount of strain, so you wouldn't want them soft. I will be wrapping my UC legs in coper wire stripped from some old electrical flex, and soft soldering.

Edited By Eifion Herbert on 08/05/2013 07:26:33

[Greybeard]

The electric soldering iron, about 60w, is the best tool for the best tool for this job. It is quite difficult to correctly tin the piano wire with a gas lamp as i know from experience. Take into account the fire risk and running out of gas mid-job and the decision becomes an easy one.

[John Miller 4]

Eifion

You are quite right the temperature needed to silver solder will indeed draw the temper from piano wire. It will effectivley become mild steel in the area where you have silver soldered, and of course this is where it will bend if strained (heavy landing etc). As has been stated, bind with copper wire (tinned florists wire is good) and soft solder.