Now I have to learn soldering...

Ô desperation...

After failing repeatedly to make a neat practice-job with scrap metal, I thought "all-right, man up, maybe it's easier with brass, mild steel and leftovers of solder on the parts...". So I made a bit of space in my tiny living-room and dived head-first into the adult side of the swimming-pool.

I prepared the job carefully, I won't go in too much detail right now about that. First attempt was kind of a painstaking success. Then I decided I could improve over it. Second attempt saw the leg come off completely... Me being an average Frenchman, the neighborhood echoed with a pretty angry "Merde !!".
I took a lot of time to prepare again, it was more difficult to hold the loose leg in position. Third attempt looked like a real success. I undid all the wires and tested the solidity of the thing once it was cold... I just ripped the leg off. Big "Merde" again heard in the street.
Fourth attempt with the stove upside-down was an utter failure.
Fifth attempt looks like a success, the leg is slightly squint but it's good enough, and everything is very messy, when I think that I had so well shined the brass two weeks ago I feel like Sisyphus.



There's a few droplets from a weld I overheated in spite of my precautions. I pressure-tested the stove with water and it seemed OK. I flushed it with meths and tried to run it on paraffin again.

But now I've got an unexpected problem. There's a poor pressure build-up, and I have flames appear just below the spirit-cup. The packer is just a few weeks old and was working perfectly before the soldering session. Moreover, with the old packer, pressure was OK and I just had a bit of smoke above the spirit-cup. So now I don't really understand what's happening.

I'll give it a rest for today, now I've got to cope with an angry girlfriend coming back from work, and that's what I'll have called my day off for this week

That was the noob story of the day. Thanks all

Mathias

 

Mathias, at least you've got it on there, and sounds as though you need a couple of Georges washers.

When soldering different thickness pieces together, you have to apply heat to the thicker piece mainly.
In this case the leg, I would let a little heat play over the tank, but it would probably get all the heat it needs with conduction from th touching leg.

Hope this makes sense.

 

Hi Gordon. It totally makes sense, it is what I had thought as well. I tried to "pre-heat" the leg around the weld too, but it wasn't enough. And with my blowtorch I'm not accurate enough to heat the leg only. Forging makes the blacksmith, and I'm not there yet

As for the washer :

- what may have happened ? This washer was nearly new, and worked perfectly just before ?

- the old washer, weeks ago, showed a minor leak above the spirit-cup that resulted in smoke and then an occasional very small rogue flame popping up. The new washer after the soldering has a massive leak that shows with a constant flame below the spirit-cup. How's that possible ? Don't you think it could be something else that went wrong ?

 

Trying to solder components on a tank with a blowtorch is asking for trouble. The best way is to use a copper soldering bit. It will get lots of heat to a localised spot without heating up the whole job.
Either a gas-fired soldering iron which will stay hot or a pair of old-fashioned copper irons in a blowlamp/stove flame is the way to go.
The heat from a propane or other single fuel, self-aerating torch is very difficult to control with any accuracy as you have discovered. If you have oxy/acetylene or oxy/propane you should get away with it.
Wet rags which boil at 100 deg. C will slow the process down but if you stop heating at 100 degrees C the solder will not reach melting point(450 deg. C ish depending on the solder).
Sorry if I sound pedantic but I do this sort of thing for a living.

 

for the future try making sure that the flux that you use does not spread to parts of the stove you do not want to solder as this will ensure the solder in those parts will melt, just clean it off with a damp rag (I assume you are using a plumbing gel flux) also make sure that the solder you are using is for water pipes and not gas as this is a lower temperature solder and it will solder quicker, as the previous post shows, try heating the steel up first, you can always hold it in place using bailing wire or failing that copper electric wire although be careful that you dont melt this during soldering, failing all that, try brazing it !

 

Hi Karto,

I've gone through this path before also. Some of my gained insights:

1. To attach a leg, I hold the stove (on its side) in a vise by one of the other legs, so that the leg to be attached lays horizontal, on top of the tank.

2. I put some wet rags on the tank to absorb the heat flow, about 5 cm away from the solder area. (This is a soldering job, not a weld.)

3. I hold the leg to be attached in "vice grip" pliers, so that I can easily manipulate it into the precise location. I apply paste flux to both the leg and the tank. I use common electricians flux.

4. After setting the hot leg in place, I carefully cool it with another wet rag, before letting go from the pliers.

5. Any surplus solder is easily removed with a steel wire-brush in my electric drill.

As to the leak in the riser tube:

1. The "smoke" coming out is vaporised kerosene, highly flammable.

2. If I do not have a suitable heat resistant washer, I improvise with asbestos-graphite packing cord, of the type normally used for packing around the valve shaft of gasoline stoves. Two turns around the tube normally provide perfect seal.

If you still cannot control the leak, try posting some photos.

Best,

Yonadav

 

I would advise against cooling solder too quickly with wet rags. This tends to cause rapid contraction which may weaken the soldered join. If you can't wait, blow on it.

If you intend to braze or silver-solder you MUST remove EVERY trace of lead-based solder before you start as the lead will eat its way through brass (and many other metals) at silver-soldering temperature.

 

Thanks to all for the input. Zincman there's nothing pedantic in sharing best practice, cheers ! I had seen this kind of metal rods heated in a fire in a tiny very "rural" workshop in Morocco, but I thought they were only doing that because they were tight on money.

Yonadav, I do not know the type of cord you're talking about, never came across that. I just made the connection REALLY tight and it seems to work so far.

Now there's only one very last thing that bothers me : I used to trust that stove, but now that I've overheated the solder on the bottom of the tank and these three little droplets have appeared, I do not really know anymore to what extent it is safe to pressurize and let run hot. Is there any way to visually judge the reliability of that bit ?

 

No!
Given time it will/might develop a small crack, but not to worry!
As a kero burner it will not catch fire just drip like a SR71 on the runway.

Heat lightly to vaporise the kero, wait and then use electronics solder with flux to seal the "suspious" place. No worries mate, just learn and become a jedi master of stoves

 

Karto,

This is the graphite cord that I use to seal around valve shafts etc:

http://shop.maidstone-engineering.co.uk/?mod=product&cat_id=3&product_id=73

Yonadav