BRYMSTON RR – EPISODE 12 – VEE have ways..
Back in episode 11 I detailed some mods I have made to jigs for producing the rail for the common crossing (the vee, frog etc) and blades for point work on The Brymston RR. The mods to the soldering jig were done because I mentioned that I intended to silver solder the Vees.
A number of comments here and on other fora were concerned that silver solder requires a higher temperature than the melting point of aluminium that the jigs are made of.
Many other things have got in the way of a practical test until today but whilst I couldn’t put my finger on the right techno babble to allay their concerns I thought they were worrying unnecessarily.
Today I silver soldered some vees without a problem and the reason it isn’t a problem and why my jigs aren’t a dribbly mess is down to mass. The jig is a bloody great big lump of aluminium which is a great heat sink. It holds the part of the rail to be soldered in clear air away from the aluminium. Added to that the heat source whilst intense is tiny.
I have now silver soldered a number of vees together and used two methods of heating. The early attempts clamped up the vee and I then added silver solder paste in to the vee. This left some surface contamination. Whilst they cleaned up nicely I wondered if it could be avoided. In this first video I have the rails clamped in place but first I applied silver solder paint to the inside faces.
Now for those worrying about the aluminium note that some liquid that is in the recess behind the joint doesn’t even get hot enough to boil away. Straight after soldering it looks a little charred but that all cleans off. From the jig the vee goes in a jar of pickle solution to clean it up, then rinsed in clean water and it cleans up to shiny metal.
Then I had an idea and wondered if resistance really was futile. Ok, so I only used that line so I could post a picture of 7 of 9. [I wonder if it occurred to The Borg that if they had all looked like 7 of 9 they’d have had a lot less bother assimilating half of the population].
What I was really wondering was if my resistance soldering unit would get the vee hot enough. Its a pretty small cross section and for soft soldering I never use it on full power anyway. Only one way to find out. Give it a go.
Well, that worked better than expected. Afterwards I noted that the very sharp end of the vee had opened slightly but I reckon either a clip or less pressure on the probes will sort that. That said there isn’t a lot to choose between fire or resistance methods for doing the vees. On other modelling projects the resistance method may be better because it only heats where your joint is as the flame is a bit wider.
Why silver solder. As you have seen it needs the bits to be red hot to solder. It will need that temperature to come undone so any amount of soft soldering I do to add other details isn’t going to cause this joint to come undone.
Onwards now to the rest of the turnout.
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