Welding Tips and Tricks

Morning Folks

I am trying to repair an old flat belt pulley but it's giving me fits. Had reasonable success repairing cast on several other occasions. I have tried TIG (DC and then AC) as well as oxy/acetylene to try to work this stuff but the cast just beads up and rolls off like water off a freshly waxed car. Doesn't matter if the part is 60 degrees or 600. Tried nickel and stainless filler with the TIG and brazing rod with the gas torch but the cast just won't behave.

I had another busted pulley that looks like it was from the same machine and was able to get a decent puddle and bead on that.
Anybody got any suggestions?

You'll probably have to braze that. There are processes for cast that work 'ok', but for the most part, it'll require a preheat, then braze, then slow cool. You might be able to tig-braze it with silicon bronze or aluminum bronze, but I've not done that on cast to offer advice on how that works. I've done lots of Si Br, just not on cast.

I have welded a lot case parts cars and truck manly the motors with cracks some farm equipment and found that aluminum bronze A2 works the best clean the metal and put a chamfer on it and Tig weld it ACHF or DCSP using a 2% Thoriated tungsten.

I guess that's where I'm going wrong is I shouldn't be melting the cast at all.

Yeah, brazing without melting the cast is the safe bet, that being said, I've welded a little bit of cast successfully myself, and my advice is to clean the HELL out of it, soak it in simple green overnight, then soak it in citric acid and scrub it down to bright shiny metal, then repeat both processes again if needed. Once you've got it as clean as you can, if you're actually going to weld it, you really kind of have to let the garbage boil out by blasting it with heat then adding in clean filler, I've had the best luck with ER312 and ER309l

Might have to bump up to high silver brazing. 45% or higher.

sbaker56 wrote: ↑Mon Nov 15, 2021 6:34 pm Yeah, brazing without melting the cast is the safe bet, that being said, I've welded a little bit of cast successfully myself, and my advice is to clean the HELL out of it, soak it in simple green overnight, then soak it in citric acid and scrub it down to bright shiny metal, then repeat both processes again if needed. Once you've got it as clean as you can, if you're actually going to weld it, you really kind of have to let the garbage boil out by blasting it with heat then adding in clean filler, I've had the best luck with ER312 and ER309l

I've had decent luck stick welding cast with nickel and even stainless rod. Probable the flux helped with any "garbage". Actually welded another part of this same machine with stainless and it has held for several years.

When I tried the nickel rod on this part it turned into a total mess. Bummer too, that rod was expensive!

Poland308 wrote: ↑Mon Nov 15, 2021 11:28 pm Might have to bump up to high silver brazing. 45% or higher.

How do think silver would compare to aluminum bronze for strength? This 20" wheel will turn at around 7000ft/min rim speed. You can bet I will be a good distance away and out of the plane of rotation when I spin it up the first time!

Strength of Aluminum Bronze
Form Rod
Tensile (ksi) 60-120
Tensile (MPa) 410-810
Yield (ksi) 30-75
Yield (MPa) 240-520
Hardness 29-98

https://www.harrisproductsgroup.com/en/ ... azing.aspx

Check out Harris. You can compare specs. There tech support is usually worth a call to find specialty stuff not listed on the web site.

I poured over Harris' site and found lots of info but nothing on strength. Did find a couple other high silver products on the interwebs that claim 85-120 ksi, so that seems pretty comparable.

Got some aluminum bronze headed my way; local shop didn't stock it. When that comes in I'll give it a go and post the results. If it goes bad maybe I'll try the silver. Even if I never use the pulley again, I like the challenge of trying to fix it.

Ive messed with both ZiBr and AlBr. the AlBr was wanting AC tigging. I only put it on the surface just to try it and see the diff between the two. Make sure the surface is CLEAN. Show us pics of your results. I also ran into an older gent who was repairing cast iron with (oxy/acet) some cast rod and a flux...he let me have some that I never used,,,,he had much more seat time than I have and made that look so dog gone easy.

Use AlBr with AC on cast iron. The AC gives you cleaning action, just like it does on Aluminum. That cleaning action helps the AlBr wet onto the surface, instead of wanting to bead up.
Jody did a video on the subject. I tried it about 2 years ago to repair a table saw. It worked like a champ.

Well today I finally got a chance to try the AlBr filler. Got to admit my tail is between my legs. After grinding it doesn't look quite so bad, but before grinding it was hideous. Couldn't get the filler to wet in. It wanted to bead up something fierce. I was on AC, advanced square wave, with 10% cleaning at first and then bumped up to 20% with no noticeable change. Had the max amperage set to 150 and experimented all over the range with the pedal. Part was preheated to around 400.

I tried to pull the puddle (more like pile) out onto the cast with the arc and by dragging it out with the rod out but the filler just sucked up and made the "pile" taller. Will put some pictures up soon. You'll see where I tried to get the arc out onto the cast and it beaded up too.

VA-Sawyer, how much cleaning did you use?

Here are the pictures

The very first photos showed some of the run off balls. It would be interesting to break a couple of them off and see if they're magnetic. You might have some weird alloy going on than hinders the repair.

Lots of pulleys are a cross between sintered and cast. Often very low grade with lots of impurities. That’s why there cheap to replace there designed to be a disposable wear part.

Poland308 wrote: ↑Sat Dec 04, 2021 6:36 pm Lots of pulleys are a cross between sintered and cast. Often very low grade with lots of impurities. That’s why there cheap to replace there designed to be a disposable wear part.

If you know of a cheap source I'd love to hear it. I'm finding prices of around $800. Maybe I'm cheap! Been haunting ebay and Craigslist hoping to find a suitable used one.

Coldman wrote: ↑Sat Dec 04, 2021 5:11 pm The very first photos showed some of the run off balls. It would be interesting to break a couple of them off and see if they're magnetic. You might have some weird alloy going on than hinders the repair.

I was intrigued by this so I knocked off a couple BBs and they are quite magnetic.

Well that's one thing off the list

Looks like pre heat is vital. Remember with tig brazing, you only want to melt the filler, not the casting.

How much preheat would you suggest? It was at 400 as measured with my IR gun. Not melting the cast was the goal but as I added heat and played around trying to get the AlBr to wet in, some got melted. I definitely worked my way up in amperage from not enough to too much and nothing seemed to work. Maybe I'll give it another go with more cleaning. VA-Sawyer seemed to think that was helpful to get the filler to wet in.

400 should be ok. Try putting the arc directly on the filler, not the casting.

Looks like Lovejoy still makes new ones. Check out a bearing distributor in your area they should be able to find you a new one

https://www.directindustry.com/prod/lov ... 77989.html

https://www.amazon.com/Lovejoy-Variable ... R7A5E?th=1

Sorry for the delay, I was down in Florida for a few days.
I believe that I was up around 30-35% cleaning, on the Balance. That is where I tend to run the Balance when welding on questionable materials.
I also use a Carbide burr to gouge out along the crack lines. This makes a smoother surface that cleans up better after the cooking pass.
Make a cleaning pass along the weld lines with just the torch, to cook out impurities, then brush it again with a stainless wire brush.

There appears to be a surface coating of some kind in the photos. I would have taken it down to shiney metal before welding.