Re: [CR]Testing the strenght of braze material I did something like that years ago

(Example: Framebuilders:Dario Pegoretti)

To: Wornoutguy@aol.com
Date: Sat, 22 May 2004 09:14:11 -0400
Subject: Re: [CR]Testing the strenght of braze material I did something like that years ago
From: "Richard M Sachs" <richardsachs@juno.com>
cc: classicrendezvous@bikelist.org

thanks, sam. this resonates with me! e-RICHIE chester, ct

On Sat, 22 May 2004 09:06:39 EDT Wornoutguy@aol.com writes: I think I spoke of this once before so I might be repeating myself. In the past in auto body we used brass braze to hold the body of the vehicle together. This was abandoned in favor of welding once the body was made unibody and the metal was high strength steel. People contined to braze. I am not an engineer but I can tell you that one test doesn't tell it all. We once took a frame rack with 10 ton towers - we took three identical peices of 20 guage sheetmetal and made them the same with three overlap joints. One we soldered with lead, one we brazed with brass, one we welded. You would expect the lead to the be the weakest bond then the braze and lastly the steel. Well guess what folks in a pulling from end to end test they all held until the steel tore. The funny thing is that car joints (also bike joints) are not pulled from end to end they take small flexing over time. Think of a peice of a coat hanger it seems strong but if you flex it over and over it breaks into two peices so plastic works just as well for a coat hanger. A material or application needs to be tested how it is used. SO many factors to consider - type of steel, wall thickness - heat used to apply the bonding

material - angles of the steel involved amount of stress encountered at the joint. I still say 3M makes a panel bonding adhesive for structural members on cars it is made to take heat, cold, stress, bending they say it is as strong as a well - we could build lugged bikes with no welding

Sam DiBartolomeo
Riverside CA