[CR]proper application of silver brazing material...

(Example: Framebuilding:Tubing)

Date: Wed, 12 Mar 2003 19:34:36 -0500
From: "HM & SS Sachs" <sachs@erols.com>
To: OROBOYZ@aol.com, Classicrendezvous <Classicrendezvous@bikelist.org>
Subject: [CR]proper application of silver brazing material...

The conversation about silver alloys used to join tubes for bike building has been interesting, but I haven't seen one point raised specifically: the silver-based and brass/bronze alloys have different optimum applications.

The silver alloys are extremely strong in shear loads (think pulling a tube out of a lug, or turning a tube in a lug), if the tolerances are within a rather narrow range. Too big a gap, and the strength falls off rapidly. In contrast, brass alloys, particularly with fillets, can carry loads from tube to tube. I'd love comment from the pros on this list, but I've always smiled when someone described as "100% silver brazed/soldered." Great for lugs, but seems to be a waste of money and a misapplication to use it for drop-outs. Besides, I find that the silver I have goes very quickly from solid to low-viscosity liquid that flows well into gaps. In contrast, the brass I use has a melting range across which it is easier to build up a bead or fill a gap. I do use silver for low-strength "stick-ons" such as water bottle bosses and cable stops. The reason there is that the tiddly bit is thermally "thicker" than the tube, using silver lessen the likelihood that an amateur like me will overheat the thin tube.

harvey sachs mcLean va.

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