Used Japanese Chisel Supper Sharp But With U Shaped Edge

[Christopher Glanton]

I just got this off Ebay. It’s really sharp, but has a slight U shaped cutting edge to it..maybe about 1/32”. I use Shapton Glass Stones from 500-16,000 grit. Should I use this as is (for bow ties and dovetails) or take it back to a flat edge and re sharpen it?

Thanks
Chris

[William Fretwell]

Make the back flat and re-sharpen. I use a stereoscope to look at edges, my Japanese chisels have a superb edge even under 90 x magnification. No ridges, no striations, no irregularities, just an amazing edge.

[Luke Dupont]

You mean the bevel side is ground more near the edges, making the profile a U shape?

There are certain flat chisels (not gouges, but similar to gouges) with intentional curvature. Could it be one of those?

If you think it's just a grinding mistake by the previous owner or just want to use it as a regular flat, square chisel anyway, go ahead and make it square.

If it's not that pronounced and doesn't bother you in sharpening or actual use, leave it as is. No need to conform to some geometric perfection. I'm a little anarchistic and add an almost imperceptible amount of curvature at the back of the bevels on my Japanese chisels so that I don't get "stiction" that occurs on a fine stone when a large face is perfectly flat. Most people probably sharpen this way anyway unintentionally. Anyway, that's a different topic, but I'm just using it to illustrate why geometric perfection isn't always even a desirable thing, and it's up to you.

Other craftsmen may tell you you're doing it wrong. That's okay, because they're doing it all wrong too. Have an open mind, try different things, and let experience be your guide. All sorts of questions are best answered this way!

FYI, even among professional Japanese craftsmen, there are some quite unorthodox approaches that I've seen to all sorts of things regarding sharpening and tool setup.

[Christopher Glanton]

Thank you William and Luke. Really appreciate the help.




You mean the bevel side is ground more near the edges, making the profile a U shape?

There are certain flat chisels (not gouges, but similar to gouges) with intentional curvature. Could it be one of those?

If you think it's just a grinding mistake by the previous owner or just want to use it as a regular flat, square chisel anyway, go ahead and make it square.

If it's not that pronounced and doesn't bother you in sharpening or actual use, leave it as is. No need to conform to some geometric perfection. I'm a little anarchistic and add an almost imperceptible amount of curvature at the back of the bevels on my Japanese chisels so that I don't get "stiction" that occurs on a fine stone when a large face is perfectly flat. Most people probably sharpen this way anyway unintentionally. Anyway, that's a different topic, but I'm just using it to illustrate why geometric perfection isn't always even a desirable thing, and it's up to you.

Other craftsmen may tell you you're doing it wrong. That's okay, because they're doing it all wrong too. Have an open mind, try different things, and let experience be your guide. All sorts of questions are best answered this way!

FYI, even among professional Japanese craftsmen, there are some quite unorthodox approaches that I've seen to all sorts of things regarding sharpening and tool setup.

[Mark Gibney]

I can't imagine it makes any difference in 99% of applications.
I'd use it until you need to resharpen.

[Cameron Wood]

I can think of four possible configurations:

- regular chisel with a curved edge, like a scrub plane
- regular chisel with a rounded bevel
- gouge (maru-nomi) convex
- gouge concave

Not sure which is being discussed here.

[Jim Koepke]

Most of my chisels and gouges have been purchased used. Some came with some strange edge arrangements. Some gouges were sharpened with indentations in the edge. In use they made what looked like molding shapes. Those may have been for coping inside corners.

One of my chisels came with a rounded shape:

493009

Since there were already a few 1" chisels in the shop there was no hurry to give it a straight bevel.

Eventually it occurred to me it was good for making a stop cut followed by a gouge to make the finger catch for sliding lids or other things:

493010

This is on a set of winding sticks that are held together by dovetails. The finger catches not only help to take them apart, it is a clue to which way they slide.

There may be a reason for the way your chisel was sharpened. Then again, it may have been done by a lack of attention to details.

jtk

[Luke Dupont]

I can think of four possible configurations:

- regular chisel with a curved edge, like a scrub plane
- regular chisel with a rounded bevel
- gouge (maru-nomi) convex
- gouge concave

Not sure which is being discussed here.

My assumption was this one:
- regular chisel with a curved edge, like a scrub plane
But I wasn't / still am not so sure myself.

[Rob Luter]

I'm still at a loss as to what the edge looks like. Lots of speculation but no confirmation.

OP - Can you post a photo?

[lowell holmes]

Lowes or Home depot can provide a diamond hone,

https://search.yahoo.com/yhs/search?hspart=reb&hsimp=yhs-ext_onelaunch&p=lowws%20diamond%20hone&type=0_1001_101_2462_102_220916&guccounter=1