Fantastic, it's great to see your metalworking going from strength to strength! That looks like a textbook result, sigh of relief! The next one(!) will be easier... Spot on- the faster you can bring the work up to temperature without overheating, the better. It gives the flux the best chance to do its job. A long period of sitting at 'nearly hot enough' may exhaust the usefulness of flux before the filler material has a chance to flow. Was that done with a big propane torch?
@IRM Nice work Ronan! I’ve more usually encountered pinholes having developed in burners, mostly in the brazing of joints, but never a split like this, with a smaller potential crack in a neighbouring tube. I use a silbraze rod with a lower silver content than I’d use for repairs to components that don’t get as hot as a burner tube and the high melting point of the silbraze justifies two blowtorches … One, this Optimus kerosene blowtorch to get the whole of the burner up to red heat … … and this MAPP-gas torch to intensify the heat at the repair, sufficient to get the silbraze to flow. Sorted, jet nipple re-installed.
@IRM Impressive result for what I'd call a smaller torch on propane, I would have thought you were running the Rothenberger on MAPP for that job.
The saga continues… I fired things up today, it’s improved, but still burns a bit yellow: Whilst the burner now passes the dunk test I think there are a couple of outstanding problems. One might be the jet and its fitting, which looks a little lose. The stove arrived with a washer under the jet which might have been a mitigating measure. The picture above is a different jet, without washer but with a little copper grease on the jet threads. I could see some slight bubbling under the jet but things settled down after a couple of minutes. Prior to using the copper grease fuel would gradually seep and soak the legs of the jet as it cooled. I am now assuming that game from the jet fitting, but may be wrong. The other problem may still be the top of the burner. There is some dampness underneath: This may be the crack in the alloy I originally identified or it may be more subtle. Are there any common failure modes that might fit either of the symptoms above? -R
Thanks @kerophile l’ve tried this with my little primus lighter but as yet have no conclusive results. Looking back at pictures I’m wondering if there is a fundamental problem with the burner: Might there be a fracture running through the centre of the burner? -R
As snwcmpr hinted, dye penetrant might be your friend here... it may show up faults, even on a cold burner...
@IRM Can you confirm Blackdog’s suspicion that you fuelled your blowtorch with propane (blue cylinder) and not MAPP-Pro (yellow cylinder)? If that’s so, and given your comment about how long it took to get the burner hot enough to melt the silver solder, I’m concerned adhesion may have been patchy, leaving pinhole(s) unfilled. John
@presscall - yes I used propane rather than MAPP. The second try went a lot faster than the first. I’ve not seen any evidence of leaks on the top of the burner, but the underside dampness around the spigot could be a symptom. I’ll be looking closer over the next few days. There was limited daylight today to do much. @Blackdog - not knowing anything about DPI than a quick google, where would I start? Might filling and pressurising tank with meths and perhaps a dusting of icing sugar on the burner be a quick hack in lieu of splashing out on a DPI kit? Btw, thank you both - and @snwcmpr for your assessments of my efforts -R
It's hard to tell from the photos, but the second attempt looks right, you've managed to get enough heat in for the filler to flow before exhausting the flux despite being on the limit of what the torch can successfully do. MAPP or a bigger propane/paraffin torch would be more relaible. You could try meths/icing sugar, don't blame me if the results aren't edible! Worth a shot, if nothing shows up you could consider a DPI kit but you're looking at £35-odd for something you may never need again, and which may not help on a cold burner. My penetrant kit is at a friend's place the other end of the country, it gets used so seldom. Adding some filler to that burner tube/chamber join you were suspicious of would be a good plan., at least you could then rule that out.
I put about 100ml of meths in the tank this morning, pressurised it and dusted it with icing sugar. After a few hours of sitting there (unlit) there was nothing to show for it. So I cleaned it up (to avoid caramelised burner) and fired it up briefly on meths. As it cooled it was much clearer where fuel was leaking from than it was with paraffin: For good measure the burner got another dusting (top and bottom) and was left to sit for about 45 mins: There was no sign of leakage anywhere else. So I get to fire up the torch again. I presume the safest course of action is to aim to over-coat all the existing joins, not just the half that currently leaks? Is there anything in particular I should be thinking of before / as I do so? Any particular techniques to cover an area rather than create a join? I’m thinking the medium filler I used around the spigot or Silver-flo 302 with a slightly lower (but overlapping) melting range are what’s needed. -R
