Crud in the puddle

boy-o-boy is that a mess . This part is the main casting that carries the tines and worm gear , and it's lots of fun to weld . I've been
welding a little then grinding all the crud out of the weld then welding again . Takes about 2 grindings and the 3rd time I weld it I finally get a fairly clean weld puddle . The biggest problem I'm having is keeping the carbide burr(s) I'm using from loading up with soft fresh weld material . I don't want to use any kind of lube on it to avoid causing even more problems with contamination so it makes for slow work grinding out the nasties . This project is not a cash job , he's going to do some backhoe work for me in exchange . Good thing he doesn't need it right now because it's slow going . Mostly because I'm getting interrupted by the bees - they keep swarming and I'm barely keeping up with getting equipment built to house the new colonies . Things are really poppin' down here in The Holler !
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Snag
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On 4/29/2020 6:54 AM, Terry Coombs wrote:

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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wrote:


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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On 4/29/2020 12:22 PM, Clare Snyder wrote:


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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wrote:



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
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