TIG success... and failure...

It's been an interesting few days at my shop. Had a bracket to repair (cracked) that I was told was steel that they had cleaned up... turns out it was stainless, welded up nice with ER70 till I saw the back side AAAAACCKKKK. Ground it all back out and hit it with some 309l, came out nice in the end.

Had a starter come in, day of troubleshooting and a long story short later, the contacts the solenoid bridges when triggered were worn to a point it wouldn't make reliable contact. Needs to be done by Tues to leave for bike week (it's on a Boss Hoss, so a compact 350 starter). Welded the worn one up with some 14ga Romex as filler, pulsed it with the pedal hard, since it was only .095 thick, it wanted to blow out really easily. Got that done, re-shaped and saved the nice lady a couple hundred for a replacement starter.

So now with a few odd ones done, I decided to make a special fitting to allow a petcock to fit into the end of a hose, basically welding an extra end onto the fitting to make the threads twice as long. Beveled the edge a little, cleaned the hell out of it, got out some silicon bronze and set down to work. Well, it wouldn't puddle, finally did a little, brought the rod in once it started and it beaded up and sat on one side of the weld, then it acted like a glob of silver solder, flattened and wetted out entirely, then sparked and flashed in a big pop, sizzled a second and set. What the hell?

Pot metal...or magnesium.

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Originally Posted by performance

Pot metal...or magnesium.

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In BRASS fittings? They were brass, looked like it, cut like it, etc.

Brass with a lot of zinc? S/F....Ken M

A lot of brass is not TIG friendly at all. There are a ton of different alloys, too. You have to really keep the heat down because of the zinc. I usually use DC, but Jody advises AC. I can't say his looked all that good, but I will try it some day. It's one of the few places where I try to keep the heat on the filler, and then wash it onto the base metal with just enough heat to get it to flow. Also take your time and let the part heat up, or preheat it. You don't want one spot really hot while right next to it is cool. Some alloys are porous and if they have soaked up oil or solvents, good luck! The best thing is to just let that stuff bake out if it will. If you need things to be leak free then you have your work cut out. There are also some fluxes that can help clean things up. Also you can braze it up for strength, then solder to seal any pinholes. For something like a petcock or hose fittings I usually just make socket joints and solder that stuff.

I once had a big job fixing a container of broken cast brass statues that were imported from India. Total crap brass and I think they just dug a hole in the ground to cast them in, as there was every kind of impurity imaginable. And of course to top it off the repairs needed to be invisible at least from the outside. Fortunately they all had an forced aged patina with liver of sulfur or something like it. It took me a long time to get a handle on welding that stuff. But once I got the technique down it really didn't take that long and the customer was thrilled with how they came out.