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20th January 2019, 20:21 | #1 |
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Silver soldering?
Anyone here give me some advice on technique and links to what solder is good? I've been given a kit to build a static steam engine, but it'll require me to do some silver soldering which I've never done before. I was going to get some scraps to practice on before trying to solder the kit together.
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20th January 2019, 21:01 | #2 |
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For model making type soldering don't use the electrical solder which has flux in it. Go to a decent model supply shop, one that stocks soldering supplies and get separate solder and flux. Practising on scrap stuff first is essential. there are books on metal model making as well. Have a read at this.
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20th January 2019, 21:10 | #3 | |
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20th January 2019, 22:27 | #4 |
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Surely silver soldering is a completely different animal to 'ordinary' soldering done with a soldering iron. I'm sure the temperatures are much higher requiring a flame (blow-lamp in the old days).
I'm going to have to get into this myself soon as have to solder up a mesh grill for an older Rover before it goes for plating, where ordinary solder is not normally strong enough and also risks melting if the temprature gets too high during the polishing. I'm guessing there will be plenty of advice and videos on the web, has bikerdude looked there yet? |
20th January 2019, 22:45 | #5 |
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Hell no! Some kits are all white metal, at the very least detail parts are white metal. Use that kind of heat the white metal (basically a soft alloy) would end up in a puddle!
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20th January 2019, 23:05 | #6 |
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Bikerdude is building a 'static steam engine' which I take to mean a working stationary steam engine, probably gas fired. The boiler for which has to be silver soldered to stand the temperature and pressure.
White metal is commonly used for small scale model railway steam engine kits (electric powered of course) and it does melt at low temperatures, less than boiling water. Special low temperature solder is available for assembling these. Last edited by p2roverman; 20th January 2019 at 23:07.. Reason: word missing |
20th January 2019, 23:16 | #7 |
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Ah, that's potentially a different ball game. I took it to mean a non working steam loco if you get my drift. The material in a scale loco varies depending on the quality, higher end ones use brass sheet with white metal for small detail parts only.
I'm not sure if I'd want to build a live steam static model for my first go at soldering, quite possibly lose the conservatory! |
20th January 2019, 23:55 | #8 | |
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Agreed. Wills, Ks, Finney, Brassmasters. all waiting for the time to assemble them (and coaches and wagons), but the Rovers get most of my time! |
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21st January 2019, 00:02 | #9 |
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For a while I had a brief flirtation with US brass models, they are something else. Imported several from the States, mainly Union Pacific Gas Turbines. Not cheap to start with but hold their value to the extent that they featured in the Wall Street Journal! If you've never seen them have a look at Overland Models.
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21st January 2019, 15:03 | #10 |
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Silver soldering does require considerably more heat than can be obtained by a soldering iron. The temperatures required will vary with the silver content in the product and will range from about 720 degrees C down to about 595 degrees C. The higher the silver content the lower the temp but also the higher the cost.
Usually an oxy acetylene torch and gas bottles will be required, A blow torch of the gas cassette type will be hard pushed to reach the higher temps and the flame is dirtier (more carbon) so this can also cause a poor joint when using the products these torches will provide enough heat for. Cleanliness is absolutely Godliness when soldering, so the joint must be mechanically clean with nothing at all contaminating the joint area. If there is any major contamination it will not work. If there is slight contamination a poor joint will be had and will not be gas or water tight and is likely to fail under stress. Use a separate flux and make it into a paste, or a flux coated rod, these are fine, but after the joint is completed make sure you remove all traces of the flux residue. It is corrosive and will destroy any paint finishes and can eventually corrode through. When soldering use the lowest temperature possible to melt the solder. Do not get the metal too hot and it should never be red hot. This will boil off some of the materials in the solder and effect the joint strength and integrity. Use the flux as a guide. If you have used paste let it dry before you attempt the soldering then as you gently apply the heat look for the flux going liquid. This is the indicator to start applying the rod. A flux coated rod can help determine the temp is correct as this will start to melt off the rod before the rod melts. Let the flux spread into the joint and then apply the rod as it melts. Use as little solder as possible and let it flow into and along the joint using the flame to control this. Do not put loads of it into the joint like you would when welding. Soldering works by a process known as surface alloying, the parent metal doesn't and should never melt and any excess solder in the joint does nothing to add to the joint strength, just wastes money and it is expensive stuff. I hope this helps, I worked for many years for a manufacturer of welding materials and equipment and part of my job was going into all types of industries helping them with welding and soldering those things they found difficult, from maintenance sheds to nuclear and petrochemical fabricators. Getting people to solder correctly was one off the trickiest because most problems were caused by incorrect technique. They got the materials too hot and put far to much solder into the joint. They tried generally to weld with a solder or brazing rod because they were never taught the correct way. Once they mastered it there problems ended and then it was just getting the right product for the job which was always easier. |
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