Another unusual sharpening method.

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If my geometry is right, that suggests to me that the very edge of the blade won't be a straight line, but instead a segment of a circle. A rather large circle (radius equal to the long wooden support), but still slightly curved.

Interestingly, I'm struggling to thing of a scenario where that would present a problem - if the chisel is doing a through cut, then it doesn't matter; for fine paring by hand, it's not going to impact; and if one was cutting a blind mortice - then a little gap at the bottom isn't a problem (indeed, often recommended, to allow for glue squeeze out). For something like half blind dovetail (which I don't think are a common joint in the Japanese tradition), then any slight curve in the base would be eliminated when paring to the line.

And for a plane blade - that's pretty much an ideal shape.

The more I think about it, the more there seems to be to commend it; however odd it may seem. Anyone think of a scenario where the gentle curve would present a problem?
 
sdjp":frptzxpc said:
If my geometry is right, that suggests to me that the very edge of the blade won't be a straight line, but instead a segment of a circle. A rather large circle (radius equal to the long wooden support), but still slightly curved.

I don't think so; regardless of the circular motion, the blade is presented to a flat abrasive at a constant angle, so the edge will be straight if the blade is flat.

It might help if you consider (as a thought experiment) spinning a faceted cone on a giant abrasive sheet.

On a related note, it's quite good fun convincing yourself that an Edge Pro jig generates a constant bevel, if used on a (unrealistically) straight bladed knife held in a fixed position.

BugBear
 
Hello,

James Krenov sharpened his blades with a side to side motion, and a little arc, though freehand. He taught his students to do the same, and I still occasionally use the technique. It is essentially the same as the video, though I didn't think anyone would invent a jig to do it! It is quite effective on thick irons with a hollow grind. It definitely produces a flat honed edge, if the stone is flat, of course. Perhaps I could hinge my elbow to a convenient wall and self jig.

Mike
 
bugbear":37i5o2s9 said:
regardless of the circular motion, the blade is presented to a flat abrasive at a constant angle, so the edge will be straight if the blade is flat.

Indeed; my error. Looks like I forgot to allow for the free pivoting on the vertical axis there; although observing it stays flat should have been the clue!
 
Here is an approximate translation of the text under the video clip:

If your desired chisel becomes unable to cut for creating a mortice when using hammers you cannot call it an acceptable blade. By using a jig in order to set the angle, a good sharpness can be achieved. When recalling the way to use it as written in the manual: “If you humbly receive good sharpness by using this whetstone the cutting quality will be perfect. This slightly wrong-feeling method may be different, but it is kind of ingenious.” You can achieve a sharpness that would surprise professionals. Sharpening the back of the single-edged blade is important.
 
I took to doing it this way (side to side) purely because of comfort - I have a Narex honing guide and I use the scary sharp method with wet n dry on glass and even thought the guide has rollers I found that using it on course papers used to grate my teeth, so I just started to rub it side to side on the glass at the side, which made it easier to hold the jig with one hand (almost like an oversized pen) and the blade tip with the other.

I also found when I got to the 5k grit paper that going side to side gave me a much shinier mirror edge compared to back & fore, I guess because the faint scratch lines are in parallel with the edge.

Just be sure your fingers don't slip because side to side is a lovely slicing motion for the blade tip!
 
I haven't used a jig to sharpen a chisel or plane iron in quite a while.
Freehand sharpening is a skill that can be mastered. If I did it, anyone can.
The other day I touched up a plane iron and in one minute, 32 seconds I was back to work (yes, I timed it).

I just don't believe it is *that* critical to have the bevel a specific angle.
 
rwe2156":36hy37bl said:
I haven't used a jig to sharpen a chisel or plane iron in quite a while.
Freehand sharpening is a skill that can be mastered. If I did it, anyone can.
The other day I touched up a plane iron and in one minute, 32 seconds I was back to work (yes, I timed it).

I just don't believe it is *that* critical to have the bevel a specific angle.


I don't always use the jig, only for "resetting" the primary angle - I would suspect that like myself once a person has gotten used to the blade angle used, touch ups are done freehand; as you imply, far too much faff for a few strokes.
 
Completely barking. See the size of that registration surface? An arthritic chipmonk with parkinsons could freehand that first attempt
 
dunbarhamlin":208mallz said:
Completely barking. See the size of that registration surface? An arthritic chipmonk with parkinsons could freehand that first attempt

Very funny, and how true!
 
I do my out-cannel gouge sideways, stone in the usual position and the gouge pointing left and right, I find it easier to keep a constant angle so the bevel ends up flat.
 

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