braising

[mcstu]

Can someone outline the briase process. I have a stick of flux covered silver solder that I want to try. Would braise be good on cast iron? I need to fix a vise clamp base.

THanks

STU

[mcstu]

apethy

Whats wrong, 40 people read this and not one of them knows how to braise?

[dseman]

Hey Stu,
Sorry about no one responding. I'm no pro at O/A or brazing--though I 've done some in the past. Far better than I trying to describe to you the process and answer any further questions this may start, let me steer you to the big companies in this arena:

https://www.handyharmancanada.com/TheBrazingBook/bbook.htm

This gives a good explanation of the process as well as specifics on their fillers. You weren't real clear in your post as to what exactly the filler you have is. Is it a silver solder or truly a flux-covered high silver brazing alloy? Any names would be helpful here. Basically the difference between soldering, brazing, and welding are the following:
Soldering is a low temp melting point filler metal which relies upon capillary action for its strength. Brazing is next up in terms of strength, which melts at a higher temperature, but still relies upon capillary action (overlapping surfaces with small gaps between). Welding involves actually melting and fusing the base metals together, usually with the addition of filler metal. This is rough definitions, but will help with your reading of the handyharman website. Another good site is

https://www.jwharris.com/welref/techguide

select cast iron and then brazing to get some further info.
Do you have access to an O/A torch, or just a propane/mapp torch? This will definitely alter which process and filler metals can be used.

Check out the sites and then get back to us with more specifics on what you've got going.

-dseman

[Jerry]

I would think that a better fix would be to stick it with nyrod arc rod. If you do so bevel broken edges and heat to between 400-700. Weld with small passes and peen the weld area a little after each pass. When done welding let item cool slowly, cover with old leather gloves or drop part into sand or whatever just try to cool slowly.

I have done some brazing also, just not on cast-iron. But in the brazing application, clean material and clamp broken pieces together. In order for braze to flow you will need to reach a heat of about 1200 and above. I would heat casting till it just started to become dull red, but meantime keeping rod on joint so as to let it flow when the temp hits the right amount.
When rod starts to melt push rod into cracked area for it will take a good bit of rod to fill broken area.
If you use a bare rod or wire you will need to flux the surfaces that you will be brazing for the wire will flow to where the flux is and where heat is directed.

Good luck

[Jerry]

Hey stu,
All of the folks on this site have various degrees of welding knowledge to draw on. One thing in common that we all have and like yourself is an interest in learning.

So if 40 people looked then most likely 40 people were intereted in your question. Stu in time you will see that there are many, very smart welding professionals who come and go on this board and they will gladly help whenever they can.

Anyhow welcome aboard and good luck bud.

[Stu Bass]

braising

Hey Guys: I see there is some other guys with the same names out here . Maybe we can seperate them a little? Noticed that on the ornementiron link to. How about I be Stu-169? You be? Thanks Stu-169

[mcstu]

sorry

Sorry for the harsh follow up guys, the info passed on was excellent.

I want to get better with my o/a system and try new things is all.

Good site/good people

[SMPARTS18]

braising cast iron

MCSTU

I'VE DONE ALOT BRASING OF CAST IRON, AND WHAT WORKS
WELL FOR ME IS A GENERAL PURPOSE BRONZE FLUX COATED
ROD. I'VE USED THIS ROD FOR OVER THIRTY YEARS, ON VISE'S
PORTABLE CEMENT MIXER YOKES, CULTIPACTORS, TRACTOR
EXHAUST MANIFOLDS ETC. I'VE EVEN USE THIS TO REPAIR THINGS
THAT OTHER WELDER'S HAVE USED THIER NICKEL BASED RODS ON
HOPE THIS HELPS YOU OUT.

SMPARTS18

[Franz]

OK I guess it's time for the Old Fart to jump in here and straighten the place up a bit.
First, "brazing" doesn't have a **** thing to do with brass, Brazing is officially defined by the temperature range it happens in, or at least it was years back when I learned. Now bein old I've forgotten the exact temps, but lets just say it happens between the top end of soldering, and the minimum temp the parent metal being brazed will melt at.
Brass, like solder & Silver solder is also limited in the gap it will fill on a proper fitup. I said GAP, and I do know you can pile brass up on something, but that is different from filling a gap on a line system.
Brass and silver also have a higher remelt temperature than initial melt temperature.
Brazing can also be done on Aluminum, but it requires hellatious clenliness conditions. The stuff they sell at demonstrations at farm shows, where you can "weld" aluminum with a propane torch is actually brazing.
Brazing is advantageous in that you can braze different metals together, such as steel to copper or stainless, without too much difficulty.
Brazing is also a very misused process, in that a lot of jobs get brazed when they could easily be welded and yield better performence. Just watch the performers at any chain of muffler shops.
Brass rods come in a wide range of melt heats too, some coated and some bare.
The downside, brass tends to be oversold to unknowing people who go make a halfassed repair, and cover it up with a coat of paint.
Can cast iron be brazed, absolutely, but it's going to cost a fortune in heat to do the job, and the repair is only as good as the man who made it. Now I know I'm gonna get flamed for this, but in 2003, unless the repair needs to sustain heat post repair, use an epoxy. Sad to say, but JB Weld is usually a better repair in terms of strength than brass, and is a lot easier to put on cast iron.
Another thing about cast iron, when working an older part, it's almost impossible to know the makeup of the iron, so making a repair weld or braze is much more difficult. Epoxy doesn't care what the content of the parent metal is.
Hint here, when you have to do any process on an old casting it will likely be contaminated with oils. After getting as much oil off by washing, bury the cast in Kitty Litter and bake it for 24 hours at over 300 degrees to draw the oils out of the cast. DO NOT DO THIS IN YOUR WIFE'S OVEN!
Now, like I said, I'm an old fart, so what the **** was the original question?

[Guest]

There's a mess of different silver brazing rods...the melt at different temperatures, and require close fit up to be effective. Silver braze is not the way to fix cast iron....if you must braze, use a brass or bronze rod and the proper flux.

BTW all of the previous info is good...they just danced around your question....sometimes so much knowledge is confusing.

As Jerry said the best fix would be to weld it with ni-rod.