My First Brazing Attempt

Posted: November 13, 2011 in Uncategorized

So here are the results of my first brazing attempt – but before you see it I want to give you some background.  I’ve never brazed before in my life.  I took a TIG welding course at the local technical college about ten years ago but have never TIG’d since then.  I did work at a trailer manufacturer for a few weeks MIG welding right after I had finished the TIG course but my back couldn’t take moving the trailer parts around all day so that was short lived.  Armed with merely the knowledge gleaned from the frame building book and some internet instruction I turned to.

Quite a learning experience.  First off I couldn’t find any thin walled tubing locally so I ended up getting some 1″ OD mild steel that was almost 3mm thick – over twice as thick as the tubing I would eventually be using but I had to start somewhere.  After mitering and cleaning the tubing I fluxed everything up with Radnor Stay-Silv (white) erring on the side of too much.  Then getting the stupid little MAPP torch lit became an exercise in frustration but I finally figured it out.  I followed the instructions that came with the torch as to how to adjust the flame and what it should look like for what I wanted to do and I was sure the flame was too low but I proceeded.  Since I was doing a fillet braze instead of lugs I used the Safety-Silv 45 brazing rod instead of the S-S 56.  I had the mitered tube in the vice so that the other tube could balance on top of the miter.  After doing a little “tack” braze I switched the tubing around so that the non-mitered tube was in the vice and the mitered one was facing up.

The first thing that caused concern was that the flux immediately got covered in black soot when I applied the flame but I proceeded undaunted.  The flux was interesting in that I had invisioned it melting and getting really runny but with hindsight it’s pretty amazing stuff.  It never got runnier than honey and after having the heat on it long enough it starting acting as the book described – it got clear and then slightly greenish yellow.  At first I was a little apprehensive about having the torch so close but knowing that the tubing needed to start glowing (and that it was twice as thick as it should be) and that the flux started acting as described I pressed on – I was even able to move the flux around with the brazing rod just as the book described.  The rod finally started melting and at first it was clinging to only one of the tubes but by applying heat to the other tube I got it to flow over to it.  I’m not sure if this is the correct proceedure but I basically put the torch where I wanted the silver to flow to.   Since the set up was in a vice and I wasn’t sure how fast the tubing gets out of the proper heat range I decided not to use the pliers to turn the tube around so I could get at the other side of  the joint.  It was a little awkward but I was able to lean over and get the back side. 

When I was satisfied that I had a decent fittet all the way around the tubing I turned off the torch and went to Mc Donald’s to grab a burger while eveything cooled off.  Then I cleaned everything off and dressed the fillet up a little.  See the results below:

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