Dale, I'm not sure what you mean when you say "can do equally well with silver or brass". If you mean both can hold a frame together for a long time than sure. However, silver brazing rod (not to be confused with lower temperature silver soldering) melts are around 1200 degrees Fahrenheit, brass around 1600. That extra 400 degrees isn't doing the tubes any good. In addition extra heat is more likely to take a frame out of alignment - one of the great challenges in making a frame as good as possible. And one more consideration is if a frame needs to be repaired, a silver brazed joint is much easier and less damaging to take apart.
The reason companies use brass is because it's much cheaper. Just a couple of weeks ago I went to get a supply of silver for my framebuilding class and paid almost $25 per once (a typical amount for one frame). Another advantage of brass is that it can fill gaps better. This is more important on the more imprecisely made stamped and welded lugs commonly used before investment cast ones became popular. They can still be silver brazed but it does take more care (which means added cost) to get the fit right. Silver wants to have only a few thousandths of an inch clearance.
Right after the bike boom of 1970 (when America finally discovered the "ten speed bike" - which is still the common definition of a bike with turned down handlebars) when American framebuilders got back from their learning experiences in Europe, doing silver brazing was a means to promote a difference between us and the established European competition. We were the lesser guys that had yet to gain reputations that sell frames so we had to point out what we did better. It was a marketing strategy but that doesn't mean it didn't have validity. We learned brazing with brass in Europe but switched to silver when making our own stuff in the States.
Now, when I have the skill and ability to choose any brazing or welding method I want, I'm going to choose silver because it's superior. There are side issues of fillet brazing and 853 tubing but the overall advantages of silver are clear. If I really want to take advantage of reducing costs I tig (Tungsten Inert Gas) weld a frame together.
As to Edwards point, it is easier to clean up a joint when it is silver brazed. The flux melts off with hot water more easily and under a sandblasters gun, it disappears more rapidly. (although if you have a sandblaster it doesn't make as much difference).
Doug Fattic Niles, Michigan USA
Norris Lockley wrote:
<< If the fillet is added at the time of building the lug, there must be a possibility of some of the fillets being melted under the torch flame when the tubes are brazed into the lugs, unless of course the frame's joints are silver-soldered to avoid melting any of the fillets. >>
Dear Norris:
I would guess that you hit on it, that Mark will now silver braze those built up lugs.
"Over here" almost every frame maker uses silver for lugs and attachments. Just one element in our higher price structure.
Plus, bike boom writers in cycling magazines and marketing by the likes of Schwinn (Paramount) and more famous individual builders hammered away at silver being so superior and that brass "damaged frames by over heating", yada yada...
It was to the point that it became hard for "pro" bike shops to sell frames that were not "silver brazed" ? Of course the reality was different; Paramounts had such a low percentage silver that it was insignificant (look at those big fat fillets on bridges!) And all those euro frames that the flock worship (Masi, Colnago, etc) used brass. Somehow this was overlooked...
As we know, a skillful, highly experienced frame builder, with that light touch and intimate knowledge of the materials, can do equally well with silver or brass.
?
Archive-URL:
http://search.bikelist.org/
Dale, I am certainly NOT an expert on frame building techniques, however, I have always been under the impression that silver "soldering" allowed for cooler temperatures and thus less overheating of tubes. That, however, is not the point of this post. The heating issue aside, in my research on the U.S. frame builder Dick Power I found that the American builders of the 1930's and 40's, especially Drysdale and probably Pop Brennan, all used brass. Dick Power switched to using silver sometime in the very late 40's or, more likely, around 1951. He did so in spite of the fact that silver was considerably more expensive in that you could buy brass by the pound very cheaply because it resulted in less clean up of the finished frame. It was easier to remove excess silver brazing material than is was to remove brass. Now, Dick was not artiste by any means, and his frames show it. But I wonder if this was, in general, one of the reasons that silver became the material of choice over brass. And, did it in fact make for an easier clean up? Edward Albert Chappaqau, NY, USA
Dale Brown
cycles de ORO, Inc.
1410 Mill Street
Greensboro, North Carolina 27408 USA
336.274.5959
http://www.cyclesdeoro.com
http://www.classicrendezvous.com