The Shop > Metal Stuff
First time brass brazing
chipenter:
Wilkinsons sell refletive fire bricks for the back and sides of an open fire .
vtsteam:
5% silver is not what you want for this.
grg12:
--- Quote from: surfdabbler on April 04, 2016, 07:02:49 AM ---- My brass is not getting glowing hot at all. I was taking it just far enough to melt the brazing rod,
--- End quote ---
That sounds a bit suspicious. Are you really sure you got brazing rod and not some tin/silver "eco" soldering alloy?
Wysłane z mojego GT-N7100 przy użyciu Tapatalka
vtsteam:
5% silver IS mostly tin.
It used to be here in the U.S. at least, that "silver solder" was actually silver braze with a very high percentage of silver (65%-95%). With the advent of lead reduction, yes, now sellers seem to advertise tin solder with any percentage silver in it as "silver solder".
It isn't silver solder. It's tin solder, with a tiny amount of silver in it. It has little more strength than ordinary plumbing solder, melts at near their temps (roughly 475-500 F). True silver solder (braze) melts at much higher temps (800F+) and has far better mechanical properties -- it is used commercially to braze carbide tips on saws, join bandsaw blades, etc.
surfdabbler:
Had some time to try again on the weekend, and it worked much better this time. I used the original flux (with a good stir to make sure nothing important was settled out. Drilled a location hole in the 'head' of the bolt, and also ground the end of the rod to roughly match the shape of the hole. I brushed in a drop of flux to the hole and to the end of the brass rod, and cut off a small piece of brazing rod and threw it into the hole from the start (you can see it in the first photo). I also managed to find some 15% silver rod at bunnings, so I used that instead of the 5% silver. From there, I heated the whole think in a small crucible.
Last time it was taking several minutes to heat up, but this time it was much quicker. I think using the crucible really helped to reduce heat loss, and cutting off a piece of the flux was a huge improvement, compared with trying to bring the rod in with my third hand. It meant that I could hold the brass rod in place with one hand, and hold the torch with the other hand. After about 15-20 seconds, it was up to temp, the rod melted, and pow, beautiful joint! I made a few crooked bolts on the first try, but a quick reheat allowed me to move them straight again.
Thanks for all the help and recommendations, and a special big thanks to awemawson for the photos of the whole procedure and great tips! You guys rock!
:nrocks:
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