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Shop Sharpening

Posted by Sandy 
Shop Sharpening
October 26, 2015 08:42PM
I've been pretty good at chisel knife and plane blade sharpening for a long time. As long as it was high speed steel and not stainless. Shape it on a fine grinding wheel and then spend twenty minutes over an oil stone. Finish up with another ten minutes over an Arkansas stone. Eventually you can shave with it.

But I've never had much luck sharpening stainless steel kitchen knives that way.

Internet comes to the rescue. Saw this on youtube. Make or buy an 8" wheel made with 3/4" inch MDF board. Put it on a high speed grinding wheel. Rub some fine polishing wax onto it while it spins. That stuff comes in sticks at the hardware store, in various grit grades.

Now use the edge of the spinning MDF wheel as if it was a grinding wheel. You can make cheap stainless steel kitchen knives sharp as a stropped razor. Lickedy split. The edge gets so sharp you can cut loose paper with it. Works just as well for carbon steel too (chisel and plane blades). But it's ten times faster than rubbing over an oil stone.

You can buy MDF wheels at Amazon for about $15 bucks with shipping. I made mine using techniques similar to the following. I did end up a bit whop sided so I trued it up by spinning it on the grinder while slowly raising a file up to meet the wheel, with one end of the file firmly planted on the bench and the other end in my two hands. Once dead round to the center hole it's ready to go.

==> https://www.youtube.com/watch?v=UBZ2WwG2LQw <== video

....although I must say! The video above and the photo below are fine in most respects but both DO show sharpening blades with the edge facing into and onto the top edge of the spinning wheel. Fine as long as yo don't f%$k up and tip the blade too much, at which point it might dig into the wheel and the then fly out of your hand. Perhaps point first into a dumb ass's chest.

I use the bottom of the wheel where it's impossible for the blade edge to dig. Works just fine. You can get to a shaving quality edge remarkably quickly. You do have to wipe the edge 2 or 3 strokes over a fine stone as a last step, to remove any burr. But boy do I get a sharp edge. For badly nicked chisels that have cut through a nail you might have to start on the other side of the grinder, with a fine grit stone wheel, and then finish up on the MDF poliser wheel. But even that proceeds quickly compared to sharpening stones.






Re: Shop Sharpening
October 29, 2015 02:28PM
A big thanks for this post.

For years I have never been able to get that top quality edge on anything made of stainless. Like you say I never had trouble with carbon steel, I just never noticed the difference before. Using chisel guides etc getting an edge on tools worked fine and my tools aren't stainless. Carbide always gets sent out. But I have never been able to get that edge on a stainless steel knife. I have several diamond stones and 1 fine Aransas stone. I always assumed it was my lack of skill at keeping the angle correct in the process. It never occurred to me that it might be the material it's self.

The video was good. It would never have occurred to me to use a wheel of MDF. One of the guys at my old shop had a glass plate grinder which did a great jog on tools using diamond paste. I never tried it on a knife.

"THE WHEEL MUST ALWAYS ROTATE AWAY FROM THE BLADE"

Good point.
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