Author Topic: Brazing issue  (Read 240 times)

Offline iosens

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Brazing issue
« on: December 02, 2017, 10:45:41 PM »
Hi
I could not find a forum about "working techniques", but this one qualifies a a failure I guess.

Trying to braze for the first time (actually second time with same results). On youtube it looks so easy and the solder flows so easy.  (see Keith Appleton)

I am using Safety-Silv 45 and Otay H-20 flux (and a MAPP torch). I am suspecting that these don't like each other but cannot find any documentation.


What happens is that the flux starts to get fluidy as it should but the rod will not melt yet. Then brown. At the point when the solder starts to get soft, the flux seems to get int a charcoal state and the solder never really starts to flow and get sucked in by capillary effects as all the instructions claim.
.
Metal has been perfectly cleaned

Tried steel, then brass, same effect ( see picture).


Offline Dave Otto

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Re: Brazing issue
« Reply #1 on: December 02, 2017, 10:54:14 PM »
It appears that this flux is for soft solder, you will need obtain some proper flux.

Dave

Online crueby

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Re: Brazing issue
« Reply #2 on: December 02, 2017, 10:59:39 PM »
Try and find some silver solder flux, like the Harris Stay-Silv white flux, or Tenacity 5 flux. Those are meant for the much higher temperatures (1200F range) than the soft solder fluxes (300-500F range). Do some searching on this forum, there have been a lot of threads that talked about silver solder techniques, not sure if there is one just for that.

Offline 10KPete

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Re: Brazing issue
« Reply #3 on: December 02, 2017, 11:00:15 PM »
Yep, that's flux for soft solder.

Pete
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SB 10K lathe, Benchmaster mill. And stuff.

Offline Gas_mantle

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Re: Brazing issue
« Reply #4 on: December 02, 2017, 11:52:24 PM »
I'm not sure where you are but here in the UK I use Easyflo 55. I'm new to silver soldering but so far I've been pleased with the results on copper, brass and steel using Mapp gas.

Offline iosens

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Re: Brazing issue
« Reply #5 on: December 03, 2017, 02:01:25 PM »
Thank you very much, that does explain it.... :facepalm:
I see now: up to 700 degrees.