Silver solder wire / rod size

[Steve RowbothamParticipant @steverowbotham77083]

I've just got to fabricating the crankshaft on my Stuart 10V and need to buy some Silver soldering bits as have never done before. I'm not sure what size wire / rod to purchase for this task that will also have wider utility for future use – 0.5, 1.0, or 1.5mm2? Advice welcomed please before I order.

[Steve RowbothamParticipant @steverowbotham77083]

[duncan webster 1Participant @duncanwebster1]

Doesn't answer your question, but I used loctite, much easier, no distortion, no machining afterwards.

[Thor 🇳🇴Participant @thor]

Hi Steve,

I have fabricated crankshafts by silver soldering (brazing), I make the parts slightly oversize so after brazing I can clean up any distortion. I usually use 1.5mm rod since that is readily available where I live but when I find 1mm rod that is what I buy. Good luck.

Thor

[Speedy Builder5Participant @speedybuilder5]

Think of silver solder as a commodity in the workshop. It will be used for more things than your crankshaft once you have some. If you have not used silver solder before, PRACTICE on some similar joints that you can chuck away afterwards.

1) You need PLENTY of heat. Most problems arise from the joint not coming up to temperature quickly enough.

2) For a crankshaft joint, I would use the HT5 flux as it has an extended life at the brazing temperature.

3) Decide what temperature silver solder you need, I would select the lower temperature one as it will need less heat. I would choose the 630 – 650 deg C type 455.

Search this site for tips on silver soldering on this site, have a look on the net eg CupAlloys

Good luck and PRACTICE before you ruin your hard work.

Bob

[JasonBModerator @jasonb]

Like Thor 1.5mm2 does me for all my fabrications including crankshafts. HT5 flux almost all the time too.

[CirclipParticipant @circlip]

With a larger diameter you can always beat it thinner if required.

Regards Ian.

[Steve RowbothamParticipant @steverowbotham77083]

Thanks all for your most helpful responses, I will purchase 1.5mm2 rod and HT5 flux. My other questions regarding crankshaft fabrication were related to pinning, but all fully answered in a 2015 thread initiated by Ferrum – what a brilliant resource this forum is for a beginner.

[Steve RowbothamParticipant @steverowbotham77083]

PS thanks to Speedy Builder5 for the reference to CupAlloys, much better than any web site I had found on this topic.

[Paul LousickParticipant @paullousick59116]

Not all silver solder is the same and contains different percentage of silver. More silver = more expensive. I use 15% silver solder for plumbing and general fabrication applications and 45% silver solder for boilers and valves, etc.

Solder with a lower silver content has a higher tensile strength and higher melting point. Solder with a higher silver content has a lower tensile strength and lower melting point but can give a stronger joint because it flows better into the joint. (better capillary action). Solders with different melting points are handy when assembling components made up of multiple parts that have to be soldered separately in stages.

[IanTParticipant @iant]

Much the same as others, I use 45% Silver, 1.5mm rod for general work. This is good for feeding alloy into the joint and also for cutting off small 'pallets' for placement. I'm afraid I've never found it that easy to beat it flat, so don't try these days. It is also quite stiff, so is somewhat awkward to form small diameter rings with.

Instead I have some 55%, 0.7mm silver wire that is much easier to form for smaller work – e.g. small rings. It gives very tidy joints on smaller work, as you don't tend to get as much surplus alloy around the joint. It also needs slightly less heat to flow well.

Regards,

IanT

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