chip deba sharpening advice

[kodo1]

how do i approach fixing chip single bevel deba
do i need need to rotate between Uraoshi side and Shinogi Surface to the edge?

[Altadan]

Could you attach a photo?

I'm inclined to say that most of your work need be on the blade face, and less so on the ura - but not neglected. but I might be wrong*.


* It will lead to an uneven height between spine and edge - from the ura's perspective, but I don't know that's necessarily bad.

[kodo1]

here are some pic

[Horizonson]

Maybe my eyes are just not what they used to be; but (to me) it looks like severe rolling of the edge, more so, than chipping.

How soft/hard is the steel temper?

Someone tell me I'm crazy and need glasses!

[kodo1]

there are some micro chips and some roll parts. guess i need to work on my fish filleting techniques and sharping single edge.
but i did use it on four 30lb white sea bass in 2 weeks those bones where a bit tough, might have to get a cheap German beater knife to cut threw those bones next time.

[ken123]

A more advanced approach is to put a less acutevedge near the heel to use for going through bones and a more acute edge near the tip to filet the fish. Takes a bit of practice. You want one continuous curve over the bkade length. Near the heel you can also focus more in the edge than the whole blade road, even going to a more convex grind.

Spend a minimum amount of time on the back of the blade - just enough to deburr and leave a scratch free finish . You want to minimize metal loss on the back, preserving the depth of the hollow grind.

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Ken

[kodo1]

thanks for the tip.

[ChefKnivesToGo]

I just did one of these and I wish I had taken a video of it.

Basically just grind it out on the right side, as Ken said, you want to grind that front bevel until you remove the chips. I usually start on the flat side to raise a little burr and then flip it over and grind until it’s acceptable. Then flip it back over to debur. Try to avoid doing a big microbevel on it. The tendency is to raise the angle up to get at the chip and then you’re left with a a knife that won’t cut as well as it should.

Show us again after you’ve worked on it a bit!

[ken123]

I just did one of these and I wish I had taken a video of it.

Basically just grind it out on the right side, as Ken said, you want to grind that front bevel until you remove the chips. I usually start on the flat side to raise a little burr and then flip it over and grind until it’s acceptable. Then flip it back over to debur. Try to avoid doing a big microbevel on it. The tendency is to raise the angle up to get at the chip and then you’re left with a a knife that won’t cut as well as it should.

Show us again after you’ve worked on it a bit!

Just to emphasize Mark's posting a bit more I also avoid unnecessary microbevels . These tend to increase the total included angle of the edge, unnecessarily dulling the blade. This is a particular problem with yanagis and usubas which can get dull to the point of being near useless. You wind up with a sharp edge suitable for a poor quality steel. Even hamaguri grinds are unsuccessful.

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Ken

[Jason B.]

I'm not a big fan of grinding the blade road to remove chips, you can really distort the geometry that way. Instead, hold the blade 90 degrees to the stone and cut into the stone like slicing bread. This will remove any and all edge damage and give you a fresh line to work from. It's the same for any chipped blade really... You don't want to go straight to sharpening the bevels before removing damage because you can end up with an uneven curve to the edge.

As mentioned you should go to the backside first once the edge damage has been removed. You need to reset the grind on the backside before going to the blade road. This is critical.

Now on to the blade road, hold up on the hard steel and avoid to soft cladding for the majority of the grinding. Once the edge is getting close to Apex microbevel with a 1k stone, just a few strokes as you don't want to distort the bevel too much. Now if the microbevel is thicker than a pencil line then you need to go back to the blade road for more thinning. FYI, you should set your microbevel around 45 degrees.

It's been single bevels repair craziness for the past two months, did 5 this week. Let me know if you need more details.

[ChefKnivesToGo]

Jason, do you use a belt sander on Deba knives ever?

[Jason B.]

Jason, do you use a belt sander on Deba knives ever?

Yes, but only if the chips are too big to remove with a stone or if the blade road needs a regrind. Sometimes if the edge is thick after removing the damage I will grind just the hard metal avoiding the soft iron and upper section of the blade road. This is simply a time saver when going to the stones as the hard edge steel can take a long time to grind down by hand.

[ken123]

Well as with most things, there's more than one approach to this.

Breadknifing an edge can be a useful technique for dealing with significant irregularities both for single and double bevel knives. Harrelson Stanley has some videos on this. It can even be useful for straight razors too. Where you divide between breadknifing and a more normal repair is an exercise in judgement.

For more extreme repairs, I do use a 2x72" belt grinder, running at a slow variable speed. The wider belt width gives you more control grinding between the soft and hard steels of a single bevel knife. Hand pressure is critical with either a grinder or waterstone. It is important to apply pressure close to the edge against the harder steel. Applying too much pressure higher up is almost a sure bet to mess up the shinogi line. DON'T do that!

I try to maintain or even create a flat blade road with no microbevel at the same angle as the original. If you go more acute you can run into a more 'chippy edge' and here you can go to a hamaguri grind. Determining this angle is also a matter of taste and experience based on your (or your customer's) perceived usage. I find that rather than going to a 45 degree microbevel that either a moderate or no increase in bevel angle (either a flat or convex grind) will suffice- just a couple of degrees.

These angles will vary with the steel and tempering process. So for instance if you are doing an Usuba with a lower quality steel, it is easy to go to too acute of an edge. You can go to a more obtuse angle, but you reach a point where you either have a chippy edge or an edge that wont cut well enough for the more challenging techniques that you might use an usuba for.

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Ken

[kodo1]

took too long on stone for me to fix, when to knife shop where they had spinning stone and grinder.

[ken123]

Could you show us a picture of the work they did?

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Ken

[kodo1]