[BC] Irons for silver soldering copper strap

[Cowboy]

On Tuesday 16 October 2007 08:48 am, Mike McCarthy wrote:
>  There's a reason we work reasonably well with each other....we're on the 
>  same page. Though I never had any luck with MAPP and strap...

 ;)

>  I do have a Turbotorch kit. But don't use it much for that reason. .

 Works fairly well on .032 strap, and it's possible, but slow, on .064 strap.
 There are two tricks.
 1. The copper must be very, very clean.
 2. No flux !

 Flux is to prevent heat oxidation, by gassing and displacing oxygen.
 A turbo-torch burns stoichiometric, so there is no residual oxygen in
 the flame, so flux serves no purpose, and may contaminate the surface
 before the bond can be made.
 Clean, is key.

 A turbo torch ( generic ) is ideal for radial work, though the bloom of
 the flame is a bit large for expanded metal ground screen, so tends
 to burn the screen before the braze flows.

 My preference for oxy-acetelene is better control.
 Much more heat, or less, in a much smaller area, but does require
 some experience handling a torch.
 For expanded metal screen, I'll always go with the oxy-acetelene
 for just that reason.

On Tuesday 16 October 2007 08:54 am, Mike McCarthy wrote:
>    How may times do you check the joints after a major 
>  local strike?
>  
>  I always fold one strap over the other in a T or angled connection, then 
>  tighten and flow the fold. 

 I never make a folded mechanical bond !!
 The reason is that should the solder joint fail, I *want* it to open up, visibly.
 It's the same reason experienced riggers always install bolts up, with the nuts
 to the top. Should a nut back off, the bolt falls out, and you can see it.
 A bolt with no nut is a failed bond every bit as much as no bolt at all !

 The downside is that the joint has failed completely, so a second strike before
 you can get there to fix it becomes more likely to cause "issues."
 My theory is that the re-flowed bad joint from the first strike is already polarized,
 crystallized, what-have-you, enough for me to consider it failed anyway, and no
 better than unsoldered copper with nothing more than weight contact.

 As always, once discussed, if it's YOUR site, I'll do it your way.

-- 
Cowboy