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How to square a knife spine with a Ken Onion Work Sharp?

E

Evolute

Joined
Mar 19, 2001
Messages
4,765
I just received my Scrapyard MS-221 knife. My initial impressions are positive. That said, I want it to have a sharply squared spine over most of the spine length (i.e., past where my thumb might rest on it), so that it will work well as a spokeshave for scraping feathers of tinder from wood, and so that it will throw good sparks from a ferrocerium rod. It came with smoothly chamfered edges that will not work well for throwing sparks nor shaving wood. So, I want to sharpen the spine myself.

I have very little in terms of experience or tools. i do have a Ken Onion edition Work Sharp knife sharpener. Would this be good for making the knife spine squarely sharp? Should I use a rougher belt or a smoother belt to sand it down? Should I press the knife parallel to the length of the grinding belt, or perpendicular to the length of the grinding belt? Should I press hard or softly? I welcome suggestions and comments, before I proceed. Thank you for any help you can provide.

P.S. This knife is going to be a user, so (though pretty knives are nice), I'm not too concerned about keeping it pristine or pretty.
 
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W

Working Edge

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Dec 14, 2020
Messages
74
That particular type of power tool (belt grinder with no backing platen,) will not give your knife the sharp corners you are wanting on the spine.
Grinding along the length of the spine with a scythe stone and/or a file will produce your sharp corners.
Hope this helps..!
Mark
 
WhitleyStu

WhitleyStu

Keep'em scary sharp!!!
Knifemaker / Craftsman / Service Provider
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Dec 8, 2006
Messages
787
I've lowered a lot of knife spines to blend the spine to the belly when repairing broken tips. To do a proper job you need a 2x72 with a platen, as Working Edge suggested. A grinder with a horizontal option would be optimal.
 
E

Evolute

Joined
Mar 19, 2001
Messages
4,765
Thank you, both.

I don't think I have anything suitable for the job, then. Perhaps I can walk into a machine shop and ask a machinist to sharply square the spine for me, for a few bucks.
 
fishface5

fishface5

Joined
Feb 3, 2001
Messages
7,071
You can use the worksharp with the low grit belts to get you part of the way there, then finish with sandpaper, but it will take some work.
Use the worksharp with a LIGHT touch to grind the domed part flattish. If the press into the belt it will just give you a rounded top. The result will be ugly but then you put sandpaper on a flat surface and carefully rub the spine against it at 90 degrees, progressing up in grits once you have it flat. Then once nice and even I would Give it a patina to help protect against rust.
 
Obsessed with Edges

Obsessed with Edges

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Apr 12, 2009
Messages
12,047
Depending on the steel type, it could be easy to do with a simple coarse stone of SiC or AlOx, or possibly even a mill bastard file, which works well on simpler steels like 1095 & low-alloy stainless (like 420HC). If the steel is receptive to it, the file especially would leave the edges of the spine very crisp, or even sharp - watch out for very sharp burrs, in using it. In using the stone or file, clamp the blade into a vise and run the stone/file in one direction only along the length of the spine to keep everything as stable as possible (avoids further rounding or blunting of the spine's edges). No back/forth with the file - just linear passes from heel to tip, to keep everything under control.

If the steel is much more wear-resistant with a lot of hard carbides, a coarse SiC stone would likely be better for that.
 
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Rat Finkenstein

Rat Finkenstein

Gold Member
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May 18, 2005
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22,673
blade grinder attachment for the ken onion would work, has a flat platen

edit : also sharpens better
 
E

Evolute

Joined
Mar 19, 2001
Messages
4,765
Quick follow-up:

I took my knife to a machine shop and asked them whether they'd do this. They said yes. I asked how much it would cost. They said their minimum charge for any work was $37.50. I walked away, figuring that we're literally talking about 10 seconds of work, and that I could buy a tool and do the job myself for less than that. (To be clear, I'm not complaining about the price. I understand that a machine shop has to charge as necessary to stay in business; I'm just explaining why I chose not to pay for this.)

Immediately after that, it occurred to me that if the problem with the Ken Onion Work Sharp for this job was that the belts had flex, which could round the edges of the spine—then this shouldn't be a problem if I try to sharply square the spine at the spot where the belt goes directly over the wheel of the Work Sharp, since that area is rigid. So, I went home and tried it myself. It did indeed only take about ten seconds, barely removing any metal—and now I have a nicely sharp spine that throws fantastic sparks from a ferrocerium rod and works splendidly as a spoke shave for shaving "feathers" off of wood to use as tinder. I'm very pleased with the results, and now feel like I have a very functional outdoor knife.

Thank you, again, to everyone who helped me.
 
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