Grinding different steel types on one belt?

T

Th232

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Oct 16, 2006
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Ok, been talking with a friend about me getting a belt grinder, and he asked about contamination when grinding different types of steel:

cause I know if you brush stainless steel with a head that's been used on ordinary steel it causes microparticles of nromal steel to imbed, and causes the whole thing to rust
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True or false?
 
I have seen a stainless steel tank end up full of holes because it was rolled on a roller with rust on it from a steel job . I am a aircraft metal worker and it is frowned on if you use the same belt to grind Aluminium and steel.
 
True, to a point, If I use a wire wheel or grinder disk on carbon steel then on stainless the stainless will develope surface rust on it. I have seen this myself repeatedly in pipe and boat fittings. I would think that the effects of this on a fine belt would be minimual and you should also be hitting your belt with a cleaning rubber. I would think that it would also be more difficult to cause once the steel is hardened and you are doing your final sanding and polishing.

Aluminium is especially bad because it is soft and the steel would really penetrate
 
I don't think it's going to kill your knife, to be honest. This is especailly true if you hand sand after. The bits are on the surface. Even grinding just 440C on a belt can leave loose bits on the surface that cause rust, one way to avoid that is to do an acid dunk after grinding.
 
Yes it's true. Any process , machining, grinding ,bead blasting etc can leave carbon steel particles on the stainless which will rust and the rusting may continue into the stainless. ...The 'dipping in acid ' is exactly what the " passivation" treatment for stainless steel is . It removes carbon steel particles and increases the protective chromium oxide layer.
 
I've never seen this question before and it's a good one.
I could see where grinding carbon steel and then switching to stainless might be a problem but not the other way around. I know that I grind mild steel for patterns all the time and then grind stainless blades using the same belt and have never seen an issue with it. These are in coarse grits. I'd imagine in finer grits near a finish, it might be more of an issue. Hogging out stuff maybe not so much.
 
There are problems, and then there are problems.
Grinding copper and then carbon steel on the same belt is asking for problems, as is grinding aluminum and then titanium, oir graphite and then titanium.
Carbon and stainless?
I don't know and, anyway, the final polishing should be made on a brand new belt to avoid excessive heating anyway.
BTW: there is no such thing as "stainless" steel. There are steels more or less resistant to oxidation but, given the right condition, any steel will rust.
Stainless just won't rust so easily, or so severely and deeply.
I've ground carbon and stainless on the same belt, and left the knives sitting on a shelf for two months in my shop, which always have one or two open doors and at least a couple of windows, and lots of humidity. Neither did rust. Why? Because I covered them with protective oil. I had my CRKT M16 rust after using it for eating Pizza because I left some tomato traces on the blade.
If you take care of your knife, it won't rust. If you neglect it, it will rust no matter what. So I wouldn't worry about anything like microparticles embedded in steel...
Just care for your knives as proper.
My experiencce in 20 years of knife using is that those who get rust on their knives DESERVE it.
It's that simple.
 
Interesting question... I'm surprised I havent seen this coming up sooner considering knifemakers regular use of stainless and non stainless steel. It is an issue which I never used to believe until I saw it first hand. It extends even to using S/S wire brushes on stainless steel workpieces to avoid particles imbedding from the bristles.

Lang
 
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