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Want to start silver brazing. What are the choices?

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
The supply store keeps the bundles of silver solder in the back room due to it's high price. A plastic container of rod is about $80 each. Is there any particular variety that is better/worse. I'm thinking about joining stainless 316. If it was not so thin then a weld would do. Anyway, I have a bunch of Mapp gas cylinders and thought about getting into it as a alternative to welding.

Is any acid based flux good enough?

How do I know if the heat is being applied correctly.

I have a butane torch and was wondering if it can be used to join small parts with silver solder. Such as insert nuts or little studs to a thin sheet.

https://www.amazon.com/Blazer-GB4001-Stingray-Butane-Torch/dp/B01M0EZKSY

(just a diversion from breaking out the Miller stuff and hoping I have a good day)
 
Like 4-40, 6-32 nuts. Stuff that a tig torch would blow through. Not that I have ever experienced this before. :willy_nilly:

What are you trying to do? Attach a 4-40 nut to a piece of sheet? How thin is the sheet? Too thin to tap? Have you considered a plate nut or nut-sert rivnut?

Regardless of the answers to the above, STAY AWAY from anything that comes in rod form your “ supplier” . Quality silver “solder”Comes in wire, sheet, paste and pre-forms. Stuff sold as rod is usually for hvac or “repair” work and could be almost anything.
 
For something small like that, I’d suggest you Sorce from a jewelry equipment shop such as Rio Grand Albuquerque. Go for “easy” silver solder, and black “handy flux” for steel. I’d probably chose a air acetylene plumbers rig aka Prest-o-lite or Smith.
 
less is more, the tighter the fit the better, do not think-do . all the people I know who are good at silver solder practice that. some are really good. Agree rio is best bet for solder, for steel I like "medium" because it is more forgiving about going over temp. hard melts last, followed by medium, then easy, then extra easy, then that rod stuff of unknown mix and gooey bits from welding stores. which case just braze with bronze or brass. brazing rod is sold by pound, solder is by ounce. good thing is less really is more.
 
What are you trying to do? Attach a 4-40 nut to a piece of sheet? How thin is the sheet? Too thin to tap? Have you considered a plate nut or nut-sert rivnut?

Regardless of the answers to the above, STAY AWAY from anything that comes in rod form your “ supplier” . Quality silver “solder”Comes in wire, sheet, paste and pre-forms. Stuff sold as rod is usually for hvac or “repair” work and could be almost anything.

The place I was considering buying the silver is a industrial supply for pipes and fittings. I'm going to see exactly what they are selling. I just have seen the blue plastic boxes that the silver comes in. Not sure but I suspect that silver is in rod form, either round or square.

If by wire it means that it comes wound on a spool like tin solder, then I will ask about that.
 
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My experience with "rod" braze alloy is that it is silver-phosphorous alloys for refrigeration. These are only used on copper. The phosphorous is the flux and prevents contamination with separately applied fluxes.

Tom
 
I checked the supply warehouse. The rectangular silver rod and spooled silver wire are only for copper.
https://www.riogrande.com/product/silver-wire-solder-22-ga/101707gp needs flux unlike the phos-silver rods the welding stores have. A good bit more heat too.
the smith/presto lite plumper's torch is the standard; many pros have moved to the smith micro oxy/acetylene torch. You can use same tanks and regulators as you likely already have. https://www.riogrande.com/product/basic-smith-little-torch-all-fuels-system-with-five-tips/500057
 
get something like easyflo 45 and the right flux for it - welding store or online. It will work well on steel, stainless, any copper alloy etc. Take care with jewelers supply places, they have different terminology for SS. You want what you correctly called silver brazing solder with something around 50% silver - if it doesn't have a silver percentage somewhere around that, its not what you want (i.e. you don't want the 5% silver bearing solder)

My personal strong preference is 1/16" dia wire - you can clip little piece and lay them in the flux resulting in super neat joints with no excess blobs of solder. How to SS has been covered over and over...its not difficult, clean, right flux, don't burn the flux etc. A bit of searching and reading would really help a beginner at it. Propane/air is plenty hot enough for small parts...but for larger thermal masses O/A is common, but has to be used indirectly to avoid burning the flux
 
I personally am not a big fan of "easyflo 45". it has a lot of zinc and boils if overheated, causing porosity. also, the solder melts close to the working range of the black flux, so I wouldn't use it with that. I'll use it on brass, or when 4 "steps" are needed. also, get cadmium free solder.
 
Thanks for inputs.

I wanted to silver solder some round press-in nuts. The ones with serrated teeth on the diameter. Getting about a 50% success rate with pressing them in a panel and having them stay in place. I even tried asking politely "please stay".
 








 
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