- posted
3 years ago
Crud in the puddle
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- posted
3 years ago
How about a coated burr? Maybe ZrN or diamond. Do they even make coated burrs?
Maybe add an air blast to keep chips out of the cut area. It helps with machine cutting. Why not with manual cutting.
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- posted
3 years ago
The real problem with things like gearcases is they are virtually saturated with oil. Surface degreasing helps - I know guys who have an old dishwasher dedicated to cleaning parts before welding - and "cooking" helps too. AKA Thermal Degreasing.Boil it in a vat of water with automatic dishwasher detergent (or even Dawn). Baking a part at
300F for a couple hours is pretty effective at driving out the oily remnants of contaminants. (an old oven for shop use is pretty handy too - works for tempering steel too)The disadvantage is you need to totally dissassemble whatever it is you are repairing - but to do it "right" that should be standard procedure anyway - - -
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- posted
3 years ago
The casting halves are bolted together for alignment . The guts are on my bench . I don't think this is a case of oil contamination as much as just a lot of dirt ground into the metal . I've been using a 3/32" lanthanated and a #8 gas lens cup , I'm going to try a 1/8" thoriated with a #6 cup when I get back on it . I'm getting too much spread on the arc , running at 120Hz with 35% cleaning . The area where this broke is heavily webbed and all little tight spaces to weld in . And I ain't the greatest TIG weldor in the world .
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- posted
3 years ago
Did you not grind away the surface to clean metal before welding? If you did then I doubt it is just dirt ground in. Castings are often porous and will soak up hydrocarbons and salts. This will cause all sorts of black crud to boil out. And hydrogen will dissolve into the molten aluminum only to come out of solution as porosity as the puddle cools. You could try baking the casting, even with a torch, to try to drive out absorbed contaminants. I really doubt you will have any better luck with the thoriated tungsten. In fact it will probably be worse. You may see the tungsten start to split at the end. If I was doing this job I would turn the cleaning balance to 50%. At least for the first few passes. I know, that's tough on the tungsten. Makes it ball up. But I learned using sine wave machines where I could not change the balance and where the tungsten balled up and I welded lots of aluminum castings successfully. Eric