[BC] Irons for silver soldering copper strap

[Cowboy]

On Tuesday 16 October 2007 09:07 pm, Bruce Doerle wrote:
>  Curt,
>  
>  I have a great deal respect for you but I differ on one of your points 
>  here. 

 It's still a partially free country.
 You can be wrong if you wanna be.
 :-)

>   Now I differ with you on 
>  using flux as we used flux to prep the strap and the stranded cable.  
>  Without the flux, it was impossible to make a secure bond between the 
>  components and solder would not flow into the stranded cable.

 Perhaps, as Lamar suggests, you simply had the wrong rod.
 Then, too, there is no substitute for experience.

 More than once, I've had to show a "professional welder" how to make a
 joint. Kinda sad.
 OTOH, I did learn from my best friend Scott, whom I've literally watched
 him MIG weld Reynolds Wrap, just to prove he could.

 More than once, it's been necessary to tin both sides before a bond
 could be made, especially silver soldering to heavy steel.
 Of course then, you're soldering to the tinning, not to the base metal.

>  We were using  
>  Mapp gas too. 

 I might suggest inadequate heat.
 Just because the solder melts doesn't mean there's enough heat
 for the surface reaction to take place on the base metal.
 This is generally where most guys fail when attempting to bond
 strap to copper clad steel ground rods. You pretty much have to
 heat to a dull purple almost-a-glow, but not more.
 MAPP gas in a turbo-torch is a wonderful tool, but not for everything. 

>  We also felt confident that the heat dissipation on the  
>  strap would prevent joint failure from the lightning surges.

 The instantaneous heat of a direct strike can go as high as 60K Kelvin.
 There's not much on the planet that will withstand that for long.
 ( it's actually that heat that causes thunder, or the audible portion of any arc. )
 Fortunately, the duty cycle is quite short. The balance of the strike
 will cool greatly, to around 6K Kelvin.

>   I took some sample copper cuts home with 
>  me and tried some different approaches; only the fluxed connections were a 
>  solid bond.  The solder penetrated the stranded cable thoroughly and bonded 
>  nicely to the strap.  

 Still sounds like the wrong rod.  Could have been inadequate heat, or both.


-- 
Cowboy