Brazing Paste

[cobra428]

Hi All,
I hate watching the TV show "How It's Made". To To many ideas. :idea: They where showing how fuel pumps where made (for cars). There was a bunch of tubing going through a plate. The "operator" applied a paste through a hypodermic to the joints. It then went into an oven and ....... the most beautiful brazed joints I ever saw.
What the hay is this stuff? Looks like it would work real good in this hobby. Some paste and a torch and .....fantastic.
Tony

 

[rake60]

It is a technological attempt to idiot proof brazing in a production
environment. It is great stuff!

Here's a manufacturers link: http://www.sra-solder.com/paste.htm

Rick

 

[Jasonb]

Several of the Model Engineering suppliers over here stock the silver solder paste. Its handy for small jobs but does have a shelf life and is quite expensive.

Jason

 

[RobWilson]

hi all
I make up brazing paste as i need it ,using a CLEAN fine file ,held over a sheet of paper, i file down a bit of silver solder then mix fillings with flux .
Regards Rob

 

[ozzie46]

hi all
I make up brazing paste as i need it ,using a CLEAN fine file ,held over a sheet of paper, i file down a bit of silver solder then mix fillings with flux .

Now that is a great idea! woohoo1 woohoo1 woohoo1 Just what I was looking for. This forum is great.

Ron

 

[cobra428]

RobW......Brilliant
Tony

 

[cobra428]

Several of the Model Engineering suppliers over here stock the silver solder paste. Its handy for small jobs but does have a shelf life and is quite expensive.

I use solder paste in my work with surface mount electronic components. Prototyping circuit boards. It had a months shelf life.......But we used it for years! Brazing "stuff" is different, but who knows.
Tony

 

[rake60]

Great tip Rob! Thm:

 

[RobWilson]

Thanks All ,
I forgot to say it works great for soldering TCT to Mild steel shanks .the under side of the TCT dose need a bit of a rough up before soldering.

Thanks again Rob

 

[CrewCab]

Top class tip Rob, .............. I think the hardest job would be finding a "clean" file :

CC

 

[RobWilson]

Try borrowing the wife's nail file CC :hDe: :big: :big:

Cheers Rob

 

[Babba]

I used work for a firm that refurbed turbine blades. A gauze would be spot welded to the aerofoil surface & a paste mix of powdered metal / god knows what would be painted onto the gauze in several layers.

The whole lot would then be fired in a huge vacuum furnace (about £2million's worth) to give a new (rough) surface which could be machined & blended back to the blades original dimensions.

A very, very £profitable business. We used to do a high pressure blade from RR's Trent engine which cost £8k new or £5k refurbed. I never saw any that flew but we had a steady stream of work from navy's & middle eastern power generators.

 

[Kermit]

Rob Wilson, sir;

I'm not trying to get all your secrets, but.. Could your reveal what your flux is made of exactly? If its a commercial brand or a home made mixture? I feel following your example and directions in this area to be wise move on my part.

Thanks for all the help you are providing
Kermit

 

[RobWilson]

Hi Kermit
I use a commercial silver solder flux paste or you can mix up a small amount of powder flux with water to a creamy paste and keep it in an air tight container ready for the next time you need it

Regards Rob

 

[Kermit]

Thanks Rob.

 

[Dunc]

Not truly brazing but the flux I used many years ago to solder gold alloys was, I believe, a paste made from borax (sodium borate) mixed with a little bit of water to make a paste. I have seen variants that used petroleum jelly (aka Vaseline) as the medium but I don't know whether the amount of borax was "as much as could be added" or a lesser amount.

To use, heat gently to drive off the water/Vaseline and then heat more intensely to melt the borax and perform the hard (gold) soldering operation. Upon cooling it leaves a glassy coating that can be chipped off.

Needless to say I have not tried silver soldering/bronze brazing using this mixture but it might be worth a try. Certainly readily available & I imagine cheap

 

[rickharris]

In my experience all brazing fluxes are some combination based on Borax

UK readers may find http://www.hindleys.com/catalogue/ a useful resource http://www.hindleys.com/catalog/product_info.php?products_id=7708 shows SIF bronz (it's pink I know not why) the flux I normally use unless I just go for straight borax for cheapness. http://www.hindleys.com/catalog/product_info.php?products_id=11157