Hello - Does anyone have a fancy way to remove rust from parts for welding? Building a small rocket foundry for melting aluminum. It sat around for a bit, now I need to remove rust before I continue.
You’ve got a few options really, depending on the size of the pieces, how clean you want them, and what welding process you want to use.
If you’re not going to treat the metal so it’s going to get rusty again pretty quickly I’d probably just clean back about an inch either way of the welding area and call it good enough. If you want the parts shiny clean then of course go for the whole thing.
The Vapor Hone is a pretty fast way to clean the parts of rust in a minimal dimensionally affecting way, providing you can lift them into the cabinet and it’s currently in service. It wasn’t looking terribly healthy last time I’m up the space.
The tried and true method most welders use is a “flap disc” on a grinder. 36 grit sandpaper discs are great, and if you pay for the good ones really really fast at removing the top layer of metal and the rust with it.
Chemical methods work well for parts that are complicated geometries, but I wouldn’t waste them on your rings if it were my money.
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Thank you, Malcolm. Basically I want them to get clean and stay clean. I’m not as much into elbow grease as I used to be, so a chemical method would be preferred. I’ll look into the Vapor Hone. Thank you for your input.
Liz
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Evapo-Rust tends to be the go-to, I do believe though I’m sure there are others…
https://www.amazon.com/Evapo-Rust-Original-contains-non-toxic-biodegradable/dp/B00M0TLQ66/
Liz,
cleaning the furnace parts may be a futile exercise. If the shell gets up to a couple of hundred degrees it will rapidly rust. You can insulate the shell so that it doesn’t
but it is expensive and you will have an unusable, small bore. Coating the shell with anything will last for 1 firing. Attached see my 27 year old furnace with a worn out kaowool liner. Left it outside in the weather 24/7. Still melts an A12 crucible of Aluminum, bronze or cast iron.
You should plan on using A12 crucibles, otherwise your fuel costs and down time waiting for the melt will become tiresome. I gave my entire set up to my buddy including an 11 ft coke fired cupola and a newer A12 propane fired furnace when I moved to Texas but I would be delighted to help you avoid many of the mistakes that I made and point you in the direction of credible resources. I was just a hobbyist, not in the trade.
Best,
Jim
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Jim - I would love to consult with you on this. It’s just a side project… one of many I’ve had cooking on the back burner for a while, but I’m wanting to move forward and bring some of my ideas into fruition. I purchased 2600 F firebrick to line the innards of my furnace plus some insulated fire blanket. Hadn’t considered yet what type of crucible… just don’t want to start a thermal problem for local fire enforcement. The rust is kind of an aesthetic consideration. Some folks like it, some don’t. I’m of the latter ilk. Prefer kind of a nice patina… maybe blueing?
Liz
I believe that bluing would burn right off at smelting temps. For that matter, browning might also burn off. Although, you might be able to reapply that with each smelting. If you go for browning, do that now, as the heated oil just locks in your rust layer. In fact, you might want a little more rust to get a good browning.
And old-time blacksmith technique is to coat it with paraffin and heat red hot. The paraffin burns to carbon but fills the metal pores. Not rust proof, but pretty good.