Decarb W/O Surface Grinder

colu41

colu41

Joined
Dec 24, 2014
Messages
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How do you guys "decarb" or grind the scale/pitting from stainless, without a surface grinder? I have a mini mill but, surfacing milling entire blades isn't really an option. I do it on a small wheel on my grinder. It works, and I've been doing that since I've started using stainless, but it just seems to have too much inconsistency sometimes, and takes a LOT of hand work to fix it. The magnet trick on a flat platen I've never tried, but I'm guessing wouldn't work well with stainless as most are only slightly magnetic. Any tips, tricks, to get more consistent results?
 
Poor man's surface grinder aka magnet and flat platen.
 
Just to clarify, "decarb" (decarburization) is something that generally happens during heat treat when some of the carbon is reduced or burned off. If I understand, you're just asking about mill scale removal?

If you like, you can "pickle" the steel, or place it in some vinegar overnight. If you want to speed the process, you can heat the vinegar.

The magnet/platen trick also works well. If the steel isn't magnetic enough, just use some double stick tape, or a couple dots of super glue. The key is to keep the blade cool though, so that the glue doesn't separate, and if you can stick a short pin in your handle to help keep the downward pressure from shearing the glue joint, that will help too.
 
Like Drew said I think it's mill scale. I also do the poor mans surface grinder minus the magnet!
 
I guess I just say "decarb" because that's how Aldo has it listed on his site :rolleyes:
And for the vinegar trick, that couldn't possibly fix the pitting with it?
Almost all of the CPM154 & S35 I've had consistent pitting. To where I'd have to grind/sand a few thousandths off of each side to smooth everything out.

I'll try it out though. I'll also have to reconfigured my magnet and make it a little easier.
 
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colu41 said:
I guess I just say "decarb" because that's how Aldo has it listed on his site :rolleyes:
And for the vinegar trick, that couldn't possibly fix the pitting with it?
Almost all of the CPM154 & S35 I've got had consistent pitting. To where I'd have to grind/sand a few thousandths off of each side to smooth everything out.

I'll try it out though. I'll also have to reconfigured my magnet and make it a little easier.
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It won't do anything for pitting, but it will help loosen and break up the scale, which wears your belt out much quicker and takes longer to grind.
 
If it's not too deep and the steel is soft you could probably whack it off with a fly cutter on the mini mill.


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Mill or forge scale can be harder than second semester calculus. Borax reinforced scale from making damascus is the worst!!!!! :D
 
You can clean it off with a medium loose scotch brite wheel, then hand polish.

If you want to use the platen then use some masking tape and make handles on the opposite side. I did this before my surface grinder.
 
Colu41, Who told you that stainless steel is only slightly magnetic. I grind CPM 154, ATS-34, 440-C, and 154 CM stainless and I can assure you that a welding magnet will grab it so hard that you have to twist the blade off to remove it. Use a magnet and your flat platen or even better first use a magnet and a disc grinder and then the flat platen. This block has eight 1/2 x1/2 round rare earth magnets sunk in it and is covered by a thin piece of steel but you can use a common welding magnet that is about 4 inches on a side and they are cheap at Harbor Freight, or you can buy a magnet from Texas Knife Supply (very strong) . I have all three but a welding magnet with a piece of masking tape on it to protect your blade from scratches is fine. I have done literally hundreds of knives this way. Larry

xhWuaklm.jpg
 
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LARRYZ10 said:
Colu41, Who told you that stainless steel is only slightly magnetic. I grind CPM 154, ATS-34, 440-C, and 154 CM stainless and I can assure you that a welding magnet will grab it so hard that you have to twist the blade off to remove it. Use a magnet and your flat platen or even better first use a magnet and a disc grinder and then the flat platen. This block has eight 1/2 x1/2 round rare earth magnets sunk in it and is covered by a thin piece of steel but you can use a common welding magnet that is about 4 inches on a side and they are cheap at Harbor Freight, or you can buy a magnet from Texas Knife Supply (very strong) . I have all three but a welding magnet with a piece of masking tape on it to protect your blade from scratches is fine. I have done literally hundreds of knives this way. Larry

xhWuaklm.jpg
Click to expand...

Thanks Larry, I have a large magnet but, maybe I'm just not using it right. I'd look for a welding magnet and see if I can't make a jig similar to yours.
 
Colu41, You might want to go to the Texas Knife supply website and look up item # MAG2 a 5 inch magnet for $19.95. Put some tape on it to protect your blade. This is the strongest magnet I have found and it is what I use now. Run your belt or disc pretty slow and take it easy but the blade will probably not move on this strong magnet. It is hard to remove the blade to turn it over. Larry
 
Cpm154 does seem to have a good bit of scale on it. I have just started using some Aebl and it is very clean.
 
FWIW, I've made my own "mag handles" by sandwiching 2 to 3 neodymium button magnets between two pieces of flat stock. The stock can be shaped basically to whatever you want for a handle.
 
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