Silver solder for custom bike frames?

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Just wondering why silver solder - as opposed to, say, bronze brazing rod - is used for joining tubular frame pieces (socket joints) in expensive custom bicycle frames.  Can someone tell me why this is preferred?
Reply:Silver solder like regular tin/led solder will migrate or suck into the joint but is stronger. Brazing is like putty and will only lie on the outside and is hard to get a clean look. Another advantage is silver solder comes in strips and can be inserted into the bore or wrapped around the tube and put together. Then after the bike is put together and aligned all they need to do is heat the joints or place in an oven at the proper temp. No real "Welding Skill Involved"Mike
Reply:don't know. I want want my frame welded.Tough as nails and damn near as smart
Reply:Originally Posted by MachinereaperSilver solder like regular tin/led solder will migrate or suck into the joint but is stronger. Brazing is like putty and will only lie on the outside and is hard to get a clean look. Another advantage is silver solder comes in strips and can be inserted into the bore or wrapped around the tube and put together. Then after the bike is put together and aligned all they need to do is heat the joints or place in an oven at the proper temp. No real "Welding Skill Involved"Mike
Reply:Does the silver solder flow at a lower temp?
Reply:Brazing does have some capallary action but requires more heat depending on the alloy. Silver soldering is actually considered brazing. Sorry I did not clarify
Reply:Originally Posted by flatbustedbrokeDoes the silver solder flow at a lower temp?
Reply:So depending on the alloy could that make a difference?
Reply:Originally Posted by flatbustedbrokeSo depending on the alloy could that make a difference?
Reply:Guess what I should have posted was     With the use of alloys(chrome molly) in bike frames wouldn't the lower heat needed for silver solder be an asset?
Reply:Originally Posted by flatbustedbrokeGuess what I should have posted was     With the use of alloys(chrome molly) in bike frames wouldn't the lower heat needed for silver solder be an asset?
Reply:AFAIK silver solder first started being used with Reynolds 753 tubing which is the 'heat treated' version of 531 (both are a manganese moly alloy). While 531 was typically brazed (lugged cappilary joints or fillet brazed/bronze welded) the temperatures involved would destroy the properties of 753. Because 753 was so temperature sensitive Reynolds would only sell this tubing to builders after completion of a test couponGiven the cost of silver solder many builders only use it when they have to but as high end lugged road frames have an 'artwork' factor to them, silver solder can be good marketing. Many of the alloys used for tubing these days are designed to be welded or brazed so issues like those with 753 don't really exist any more, stainless fittings (dropouts etc) are becoming more popular though...Some more on the subject... http://desperadocycles.com/The_Lowdown_On_Tubing/About_Steel_Tubing_page4.htm
Reply:From my understanding  - and I'm not a pro -  brazed joints made with bronze rod are stronger than silver-soldered ("hard" solder).  Is that right?But I take it that a good hard-soldered socket-type joint in a bike frame can be very strong (or at least, strong enough for the task).Anybody care to discuss strength of hard-soldered joints?
Reply:Just to be clear, are you talking about the brazed-lug style construction method? If so then both silver and copper based alloys have been used for years with that process. Brazed-lug is one of the oldest methods of joining thin wall tubing for structures, it pre-dates fusion welding. In the early years of the teens, people were having trouble fusion welding some of the "new" high strength steels due to what would be later learned was poorly controlled sulphur levels. However brazing worked well, so they seemed to use that process on motorcycles, bicycles, and aircraft to about 1918-1920 until the issues with the metals were resolved for fusion welding. Bicycle companies seemed to carry this method on for many years after, along with fillet brazing ( schwinn ), perhaps just as tradition or ease of production assembly in jigs. Its light, proven, and very traditional and professional. In fact it actually allows a slightly lighter frame over fusion welding, as the requirements for wall thickness decrease due to lower specific loading it the areas of conection. It shows up quite a bit in modern car construction, however its more stampings brazed together rather than tube. 45% silver brazing alloy is a common choice.
Reply:Originally Posted by makoman1860Just to be clear, are you talking about the brazed-lug style construction method?
Reply:And still curious to learn: anyone know the strength of silver-soldered joints, as compared with say brass/bronze brazing or welding?
Reply:I would say that with a bicycle frame's sweat soldered tube and socket joints, braze and silver would show no difference in strength. Without checking, it seems like the yield of both solders is in the 30,000 PSI range. That number might include the Denrep 50% safety factor.My gut says that for a joint without any other mechanical connection, braze would be superior to silver.Good LuckLast edited by denrep; 07-15-2009 at 11:25 AM.
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Reply:Originally Posted by denrepI would say that with a bicycle frame's sweat soldered tube and socket joints, braze and silver would show no difference in strength. Without checking, it seems like the yield of both solders is in the 30,000 PSI range. That number might include the Denrep 50% safety factor.My gut says that for a joint without any other mechanical connection, braze would be superior to silver.Good Luck