Motor oil on grinder plates????

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ronbo
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Motor oil on grinder plates????

Post by ronbo » Sun May 16, 2021 15:21

Hi Everyone,
Thanks again for all the invaluable advice you freely share!

This is REALLY odd. I came across a deal on a used, lower end electric grinder on a local neighbors social media forum. It looked alot like the Kitchener #12, 0.5HP grinder I currently use (purchased from Northern Tool in the US). Nothing fancy, but basically the same and the price was $20 for the entire unit (base, hopper, augur, blade, and 3 grinding plates). I figured that for $20 its worth it just for the parts should I need them at some point. And best case I could maybe run both machines in parallel to do a coarse with one and then immediately fine grind with the other. What could go wrong???

So when I get the thing home I give it a complete and thorough cleaning inside and out, of course. I soak all the metal parts in super hot soapy (Dawn brand grease cutting dish soap) for 30 minutes and then scrub every nook and cranny. This includes the three grinder plates. My process for drying all my plates is to wipe well with paper towel and then heat them over low heat directly above the gas stove burner for 30-45 seconds. This has always worked well at ensuring they are bone dry with no moisture remaining.

Well, the plates from this used grinder did something really weird. After washing and drying I put them on the stove for the customary quick heat drying technique. After 30 seconds on the heat they started to smoke and a brown oil beaded up on the surfaces. It smelled like motor oil and looked like motor oil. So, my conclusion was they must have never been used before and that this was some machine oil left over from manufacturing. I just need to wash them again and better this time. At least thats what I thought. The second time on the stove all three plates did the exact them thing. They exuded industrial-like oil as if it were coming right out of the dry metal. My guess is that this is oil that is impregnated deep into the surface irregularities of the metal from some aspect of manufacturing. Some research revealed that and old process for hardening steel used something called oil quenching where the red-hot metal is submerged in used motor oil. Another is a blackening technique for rust prevention with uses motor oil. Its similar to how I season a cast iron skillet by coating with oil and baking.

Does anyone have any ideas on how I can get the oil off these plates? I cant use them with this industrial like oil on them. I know its not a vegetable oil, guarenteed. Perhaps theres a better solvent that's food safe? I tried denatured alcohol and again soaked them in 2:1 Dawn: water, but neither did any good.

I considered just throwing them out and using my existing #12 plates from my other grinder but thats when I realized another oddity from my "used grinder deal". These plates have tabs, rather than notches for fitting into the augur housing. So, my existing plates arent compatible. Rats!

Im including some pictures of one of the plates with the oil bubbling up on the surface after the heat/drying on the stove. Any ideas you might have would be very welcome.

https://postimg.cc/gallery/jfKxkB6
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Bob K
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Re: Motor oil on grinder plates????

Post by Bob K » Sun May 16, 2021 18:23

Fact is oil cant impregnate steel as it is not porous. It has to be a surface coating. I would try burning it off with a torch or on an outdoor grill.
ronbo
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Re: Motor oil on grinder plates????

Post by ronbo » Sun May 16, 2021 20:52

I agree, Bob, that it must be on the surface. But it surely doesnt appear to be. I would think that a film so thin as to not be visible couldnt produce so much pooled oil. Yet, it is. I like your idea of burning the impurities off with a torch. Im not a metalurgist and only know the very basics of metal working. Do you think its likely that using propane torch could ruin the hardness of the metal?
Thx Ronbo
Indaswamp
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Re: Motor oil on grinder plates????

Post by Indaswamp » Mon May 17, 2021 04:59

I would not heat over 350*F as that may affect the temper on the steel...
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