Silver Solder

[John Bateson]

It occured to me in a rare waking moment that the usual problem of bit falling off complex assemblies during soldering - in spite of heat sinks which always seem to have a habit of falling off - could be partially overcome by using differnt grades of solder.
i.e. assemble the main coupling rods with silver solder and then solder the pins which connect them using normal solder.

Does anybody do this? Is there a lower melt point than silver solder that might be a better alternative?

John

[nigelcliffe]

Silver solders melt at really high temperatures (high for most model makers). There is a fair chance of oxidising the metal, and altering its ductility. It can be done at home with a blow-torch, the metal must be free of all contamination, and the appropriate fluxes used.


Normal soft solders melt at a variety of temperatures. Lead based ones range from around 140C, through 188C to 225C (all approx). This is done with differences in the alloy composition. Carrs, amongst many others, sell ranges of solders which melt at different temperatures. Traditional lead-tin (60/40) electrical and plumbing solder melts at 188C.

For your specific problem, I'd suggest soldering the rods with one step higher soft solder, then drop the temperature grade of the solder for the pins.

Heat sink methods include damp tissues. Temperature control can be helped by using a large wattage iron with temperature control, or possibly a RSU.

- Nigel

[grovenor-2685]

Its worth a look at the C&L site, http://www.finescale.org.uk/show_page.php?pid=101 Brian has a couple of useful data sheets to download and does sell a "step solder" kit with a number of different grades included so you can try this out.

You should not need to get into Silver soldering for anything on a 4mm loco. I have only used it once, see http://www.norgrove.me.uk/pointops.htm
Regards

[DavidM]

Martin Finney used to recommend using silver solder for assembly of his inside motion kits. It was used to attach the cranks / eccentrics to the axle, so that the axle could subsequently be removed between the crank webs using a carborundum slitting disk in a mini drill - the heat generated might presumably melt a conventional solder joint. Additionally, a stronger join results at a point of potential weakness. I have only used this method of assembly on one occasion - sucessfully, I'm happy to say. You have to be careful during subsequent wheel fitting/quartering though - the phosphor bronze cranks can easily be deformed as they seem to lose their strength!

David Murrell