Japanese Markingknife how to "bend" bevel ?

[Philipp Jaindl]

Greetings,

I just recieved a Japanese Markingknife today, and I'm prettty new to Japanese tools as a whole, hoping someone can help me.

Standard procedure i removed the varnish of it and gave it a couple swipes on the DMT to check the back for flat, most of it is Flat except for the part that matters about the last 2mm on one corner and about 4mm on the other the theres a slight bend that raises that corner up quite a bit.

I have read Toshio Odates book and he does mention to tap it with a hammer over a corner of a hardwood block to bend it down, i tried that but didnt have muhc success. So I'm hoping one of you can help me on how to bend it down or what to do, I'd rather not grind it back that far and i dont wanna lap the back that aggressively either.

Are there any other options or what can i do? It wasnt expensive enough to bother sending it back.

[Stanley Covington]

Greetings,

I just recieved a Japanese Markingknife today, and I'm prettty new to Japanese tools as a whole, hoping someone can help me.

Standard procedure i removed the varnish of it and gave it a couple swipes on the DMT to check the back for flat, most of it is Flat except for the part that matters about the last 2mm on one corner and about 4mm on the other the theres a slight bend that raises that corner up quite a bit.

I have read Toshio Odates book and he does mention to tap it with a hammer over a corner of a hardwood block to bend it down, i tried that but didnt have muhc success. So I'm hoping one of you can help me on how to bend it down or what to do, I'd rather not grind it back that far and i dont wanna lap the back that aggressively either.

Are there any other options or what can i do? It wasnt expensive enough to bother sending it back.

Help me understand. By "last 2mm on one corner" do you mean the point is curved/bent away from the flat? by "4mm on the other" do you mean obtuse corner opposite the point (aka "heel") is likewise bent away from the blade's flat?

[Philipp Jaindl]

Yes when i place it flat on the stone the last part of the blade is raised up away from it, one corner more then the other .
Heres a picture that hopefully clarifies
https://imgur.com/a/uM0SA

[Rob Luter]

Yes when i place it flat on the stone the last part of the blade is raised up away from it, one corner more then the other .
Heres a picture that hopefully clarifies
https://imgur.com/a/uM0SA

If I'm seeing the photo correctly, the side shown doesn't need to be flat as the edges are beveled. You need to flatten the opposite side.

[Stanley Covington]

Yes when i place it flat on the stone the last part of the blade is raised up away from it, one corner more then the other .
Heres a picture that hopefully clarifies
https://imgur.com/a/uM0SA

Philipp:

Thanks for the pic. I understand now.

There are four ways to solve the problem:

1. Grind down the ura (flat) until the cutting edge is planar. It doesn't look like it would take much grinding on a kanaban or diamond plate to make things right. Since this is not an expensive blade, and just a marking knife, it would not be tragic;

2. Leave the blade as-is, and use it. You would need to lift the blade when sharpening the ura to contact the stone, and, you would need to hold the knife at a bit of an angle when using it. Not ideal, but it will work. Over multiple sharpenings, I expect the ura would wear to the point that all would be planar and hunky dory.

3. Put the tip (last 13mm) of the blade in a wooden-jawed vise, and carefully bend the blade's cutting edge towards the ura. Just a tiny bit will do the job. You will be surprised at how much the blade can bend without cracking. BUT, there is some risk of cracking it, so don't overdo it;

4. Tap the blade's ura out, just as if it is a plane blade. If No. 3 bothers you, this will definitely work, and with little risk, assuming of course you can use a hammer with some accuracy.

Stan

[Philipp Jaindl]

Philipp:

Thanks for the pic. I understand now.

There are four ways to solve the problem:

1. Grind down the ura (flat) until the cutting edge is planar. It doesn't look like it would take much grinding on a kanaban or diamond plate to make things right. Since this is not an expensive blade, and just a marking knife, it would not be tragic;

2. Leave the blade as-is, and use it. You would need to lift the blade when sharpening the ura to contact the stone, and, you would need to hold the knife at a bit of an angle when using it. Not ideal, but it will work. Over multiple sharpenings, I expect the ura would wear to the point that all would be planar and hunky dory.

3. Put the tip (last 13mm) of the blade in a wooden-jawed vise, and carefully bend the blade's cutting edge towards the ura. Just a tiny bit will do the job. You will be surprised at how much the blade can bend without cracking. BUT, there is some risk of cracking it, so don't overdo it;

4. Tap the blade's ura out, just as if it is a plane blade. If No. 3 bothers you, this will definitely work, and with little risk, assuming of course you can use a hammer with some accuracy.

Stan

Thanks Stan, i tried the Hammer method again and it worked this time seems i didnt let enough protrude from the block the first time. Managed to sharpen it up and waiting to use it tomorrow, though i still need to get another sharpening stone to really polish it out my DMT 8000 doesnt polish anywhere near as well as id like.

[Rob Luter]

If I'm seeing the photo correctly, the side shown doesn't need to be flat as the edges are beveled. You need to flatten the opposite side.

Duh...unless I'm seeing a hollow :o

[Philipp Jaindl]

Duh...unless I'm seeing a hollow :o

That is indeed the hollow, but i can see why you thought otherwise.