Correcting a misaligned silver solder joint

[IRTParticipant @irt]

I have soldered a couple of pieces mild steel together, and they ended up with a small twist. About 1mm over 120mm.

It is the frame of Myfordboy's powered hacksaw.

I think this twist will result in the blade trying to move sideways about 0.5mm during the cut.

I would like to re-work it for my piece of mind.

My question is: Do I need to break the joint and clean back to base metal, or can I simply clean the surface, re-flux and re-heat – maybe adding more solder if required.

I am using easy-flo/silver-flo55.

Thanks.

[IRTParticipant @irt]

[SakuraParticipant @sakura]

Should be ok to clean, reflux and sweat together, adding a bit of solder if necessary. I've never had a problem doing this. When I join a handsaw blade I "tin" the two ends and just sweat together. If that holds, anything should.

[IRTParticipant @irt]

Hi Sakura.

Are you soft-soldering or silver soldering? I have not considered tinning silver solder before because of the cleanup that would be necessary.

[SakuraParticipant @sakura]

Silver soldering, using a Eutectic solder and powder flux. Never had any problems. Eutectic is probably not the same as J & M.

[duncan webster 1Participant @duncanwebster1]

Can't you just 'calibrate' it using a decent sized hammer and vice. Bend it remote from the joints

[IRTParticipant @irt]

That maybe an option.. 18 mm hex bar will need a bit of calibrating though.

I am keen to improve my silver soldering, so all practice is a good thing.

[Jeff DaymanParticipant @jeffdayman43397]

To re-calibrate heavy-ish bar, for twist, weld a 4 foot or 6 foot piece of heavier bar or channel or what-have-you perpendicular to the piece to be twisted, at its' end. Mount piece to be twisted in vise. Drink a pint of Guinness (for strength). Twist the heck out of your bar, teach it some manners until it is straight to the last micron. Cut "wrench" bar off. If you don't have a welder your local agricultural repair shop, millright, structural steel firm, blacksmith, farrier or car mechanic probably does.

[JasonBModerator @jasonb]

Just put some flux around any exposed solder and reheat, once solder is liquid adjust the position and then allow to cool

[duncan webster 1Participant @duncanwebster1]

If I'm understanding it, it's the downcomers that want bending, not the hex bar

You'll need to get it hotter to remelt than you did to silver solder it in the first place

[IRTParticipant @irt]

I had heard that it needs to get hotter the second time.

That is partly why I asked the question. I wondered if something changed that could effect the joint strength if remelted

I could reheat the bar and bend it I suppose, but I do think that I think resoldering would be the better option.

Thanks all who gave advice. I will sleep on it, and try to make the fix tomorrow.

[Tim StevensParticipant @timstevens64731]

The reason a made joint requires more heat to move it, is because when you solder a joint, you don't need to get the whole joint to melting point (of the solder). You can do one side, turn it over, and re-heat for the other side (etc). When you need to reposition, all the solder needs to be melted before it will move. Not necessarily hotter, just more consistently hot all through.

Cheers, Tim

[IRTParticipant @irt]

Re-fluxed, clamped and reheated. The part moved into alignment without issue.

The other end didn't fall of either.

Thanks again for all help.

[Author]

Posts