Anyone good at BRAZING? --> brass screw to a steel conduit box???

[USAeng]

We tried brazing between the head of two little 8-32 brass screw and the metal conduit box... the customer wants it to be permanent/tamperproof and requested brazing....

unfortunately we dont have experience brazing and when we tried it looked like crap...

We are trying to use this bronzish lincoln electric brazing rod that comes with a flux coating that you can get a lowes.... its about 1/8" dia.... could be a few years old too

Is this rod crap? or too big? we are also using this little oxy-aceteline torch setup which uses the little mini canisters you can get a lowes...

would be be better trying a different method of fixing the screws to the box? you cant tack weld brass to steel enough to make it "permanent" could you?

 

[USAeng]

one solution we just found was using a silver brazing rod... seems to work much better... must have a lower melting point... any other suggestions?

 

[tomwalz]

If it is strong but just looks bad try braze stop maybe from Nicobraze.

Our web site has an awful lot of brazing info on it.

We use High silver alloys in the 49% to 56% for high strength and lower temperatures.

I have been brazing 30 years and doing failure analysis for maybe 20 years. I'm just not sure where to start with this question.

Feel free to call.

tom

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[moltenmetal]

Presume the "metal conduit box" is steel. If it's galvanized, suspect you'll have more success by removing the zinc first!

As you observed, you need a silver braze that melts a lot lower than your brass screws do. Those braze rods from Lowes you tried are intended primarily for repairs to steel parts, and are higher melting.

 

[USAeng]

nice... thanks a lot... I will definately be thinking more about the melting points of what I'm trying to have brazed in the future as I'm picking out the rod...

 

[ornerynorsk]

1/8 inch rod is waaaaaay too large for 8-32 screws.

 

[MikeMet]

Also, you have to have a very close fit between the head and the box. Too large a gap and the braze metal will simply flow through and slough.

 

[tomwalz]

Check the melting temp of Zinc then consider that it fumes before it melts.

Zinc is in high Silver braze alloys as a temperature suppressant among other things. By the time you hit the Liquidus and achieved a proper flow you have lsot a lot of Zinc to fuming. The reflow temp is maybe 50 to 100F higher due to Zinc loss.

What about epoxy?

Tom

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

Good engineering starts with a Grainger Catalog.

 

[Mr168]

I'd solder it, or if you have to braze it, TIG braze it using an Everdur (silicon bronze) rod.

 

[Tmoose]

Would they accept a pop rivet?

Seems like cleaning, prep, brazing/soldering, cleaning, restoring the conduit box finish would be mighty labor intensive, and might relax the screw's clamping force to boot.

 

[Ron]

I agree with MR168...just solder it. It sounds like your necessary temperatures are too high.

 

[Sparweb]

Why are you trying to weld/braze at all? Why can't you buy or make a 8-32 stud whose head can be pressed or upset against a hole or a boss in the steel box wall?

In general, when you get to the point of using a process you know noting at all about, seriously consider how to accomplish the same task with tools and techniques you do know.

Steven Fahey, CET