Tag Archives: silver soldering

Dash to the North – the completion of the Silk Scott frame

I have a whiteboard in my workshop and it generally lists too many tasks that I am a reasonable amount of effort away from achieving. This last week however, I managed to get some significant ‘to do’s’ rubbed off the board.
The Silk Scott frame had been waiting at Alan Noakes’s workshop for me to come up with a plan for the final brazing solution. The lugs had been made to be brazed with a capillary fixing which really needed oxy-acetylene. I must admit that we hadn’t fixed the exact type of brazing material we were going to use and this was all part of the delay. I saw a clear weekend coming up and thought that this was my chance to push to get it finished. So the plan unfurled: first to get oxy/acetylene.
We’d had a plasma cutter at work that we’d bought from machine mart (please no comments). It was around £600 new and lasted a year and a day. The warranty department, were sympathetic but not quite to the point of being reasonable or useful, and I was told (after paying for the service) that it could be repaired for a sum of 500 and something pounds. I declined their kind offer. We’d only used it a handful of times to make register plates for woodburners and other bits and pieces. Normally around 3-4mm thick steel for a machine rated for 10mm. Anyway, since this incident I am resolved not to use them again and so was without any metal cutting equipment at work apart from grinders. So, I figured at £5 each per month for bottle hire, I could justify the oxy/acetylene. My Dad had an old portapak I could have and so I found myself at BOC sorting out an account last week.
I called Alan from the shop and enquired as to whether he’d got any prior arrangements for the weekend, and asked about rods. He didn’t and It didn’t seem that they had anything suitable, so I left with two bottles hoping that I could sort out the rest in the following few days.
I remembered a conversation with a man called Arthur Sosbe not long ago. Arthur, though now mostly retired, is a Leicester welder held in very high regard by my father. He is also a vintage motorcycle enthusiast and I believe used to race a velocette that used to lurk under a cloth in his workshop. I myself have known Arthur for many years and he has repaired many a Scott crankcase, as well as frost damaged barrels and many other fragile vintage parts.
Arthur had said that he’d naturally use silver solder, but when I quoted him a 0.010″ gap, he said that it was too wide and he suggested something else. I remembered this conversation and also that many lugged cycle frames used silver solder and I did a bit of research. A company called ‘Cupalloys’ came up as being suppliers of silver solder to model engineers, so I gave them a ring. I’d since confirmed the gap with Alan as being nearer 0.006″, which was within the capillary range for a 38% silver solder alloy which also apparently had the benefit of melting over a reasonably wide heat range, which gave scope to also create fillets.
I bought two packs of 5 rods, and at over £4 per rod, I hoped this was going to work.
So Friday came and later than I’d hoped, I packed the Moss crankcase destined for the Silk Scott into the van and I headed up country to Leicester to see Roger and to get the portapak and hoses/ regulators I needed to take up to Alan. I didn’t arrive until after 9pm but we gathered all the bits and pieces together, as well as a trophy I’d been awarded by the British Historic Racing club, the ‘Aotearoa Trophy’, gifted once to the club by a New Zealander. I believe it’s supposed to be the best performance of a 1930 and under bike. I won it last year also, and although it’s not that I actually won a race, it’s a beautiful shield with names going back many years.
We chatted, a lot, and eventually I got to bed around 1.30am.
So up and off to Alans, the offside front wheelbearing of my van starting to whine somewhat irritatingly.
I arrived at Alan’s somewhere after 10.30am and had thoughts that I might need to find a B & B for the night, as I didn’t know how fast the job would go with untested equipment and solder. I needn’t have worried because apart from Alan having to adapt some spacers to fit the crankcase, the whole process went very quickly.

Moss Scott crankcase fitted into frame - just to be sure!
Moss Scott crankcase fitted into frame – just to be sure!
we did take a few minutes to try to establish that the frame was straight prior to fixing it, and to that end I took a sight from the rear engine mounting to a straight edge laid over the bottom face of the head stock. This looked spot on, although pretty much every other tube in the middle looked like it was in a slightly different position. I realised that it was simply built this way from new and that as long as the main datum points were correct, the bits in had some ‘tolerance’. That of course is one of the joys of a low production handbuilt machine. Every one is truly different!
So onto the hot work and (making sure the detachable lugs all faced in the correct directions) using a propane torch and the oxy-acetylene, Alan soldered the new cradle assembly into the frame within a few short hours.
Alan at work 001
Alan at work 001

closer...
closer…

Nearly finished...
Nearly finished…
I was very grateful for the sandwiches made by Margaret for lunch and delighted with the way the frame came together.
with a thanks and farewell to Alan, after he’d showed me some detailed bits he’d made for Scott TT replica forks,
Scott TT replica fork crowns
Scott TT replica fork crowns
I shoveled my frame and the bits and pieces back into the van and headed back to Devon. A quick stop in at my dad’s to show him the results, but all in all a great result for the weekend.. and I was home on Saturday night.