Need some dimension help on a deba

Sando

Sando

Knife Maker
Joined
Jul 4, 2002
Messages
1,148
Heading to MN for our family reunion, which always involves filleting a ton of bass. This year instead of a narrow, thin western fillet knife, I want to try a wide, thick Japanese deba.

The more research I do on debas, the more puzzling it becomes. These heavy beasts are usually 7mm/0.275" thick at the handle and then distal taper to some unknown thickness just back from the tip. And they are single beveled without any or much of an edge bevel. So ....

If the blade is 0.250" thick and the bevel is 0.75" wide, then the edge angle at the base is 19.5 degrees. That sounds reasonable, as that part of the blade is for chopping bones.

If the blade distal tapers to .050 and the bevel is a consistent 0.75" wide, then the edge angle is ~4 degrees. That's way too thin for an edge!

So does this sound correct (I've never actually used a deba, so I don't know)?

- 0.250" thick, tapering to 0.130" with a 0.75" wide bevel. That way the edge is ~20 degrees at the base and ~10 degrees at the tip.

Question 2:

- Would it be a sin to make it a double bevel?

I can't seem to get the hang of using a single bevel knife. Of course, the bevel would be half as wide to keep the same edge geometry.
 
Have you looked at the chefknivestogo website? They have videos for some of the deba knives they sell, e.g., the 180mm DOI blue #2 or Sakai white #2. I have not watched the deba videos, but their videos typically give you a good idea of the blade geometry, including measurements for the distal taper.
 
7 mm is really thick even for large debas. I think most regular size (18cm) are around 5mm tapering to about 3mm.

The first knife I ever made was in a knife making course (ground by the course teacher), a 5 mm deba with double bevel in n690. I used it this April to filet a 60 kg tuna including cutting off the head, tail floss and cutting through belly bones.

Check out the western deba by Tojiro. Its basically a chef knife with a bit rounder tip, heavier spine (4mm if I remeber right) and a slight convex grind. There is a good video on it from pro chefs on YT showing off the knife (not a marketing gag).

What kind of bass are we taking about here?
 
FredyCro said:
7 mm is really thick even for large debas. I think most regular size (18cm) are around 5mm tapering to about 3mm.

The first knife I ever made was in a knife making course (ground by the course teacher), a 5 mm deba with double bevel in n690. I used it this April to filet a 60 kg tuna including cutting off the head, tail floss and cutting through belly bones.

Check out the western deba by Tojiro. Its basically a chef knife with a bit rounder tip, heavier spine (4mm if I remeber right) and a slight convex grind. There is a good video on it from pro chefs on YT showing off the knife (not a marketing gag).

What kind of bass are we taking about here?
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Hmmm, I thought 7mm was too much. However, most of the knives I found at japanesechefsknife.com were that size. Dude if you did a 60kg tuna with a 5mm.... well that's just too cool.

The western Tojiro looks more narrow too. Hmmm.... I think I'll stick with the more traditional shape and handle (but still double bevel).

BTW - Large mouth, most in the 1.5 to 2.5lb range. Of course there's the rare walleye for treats.

H Hubert S. Thanks, I found this video:
That Deba is over 7mm at the spine but, there is a bevel towards the edge. In other words, it's not 7mm where the edge bevel starts. Plus there's the hollow grind on the back. So that's gonna reduce weight too. The reviewer also mentions there's very little distal taper! That changes my dimensions quite a bit.

fitzo fitzo hahaha - Yeah, I'll be bringing the 20 year old fillet knife I made too. The kids usually fight over who gets to use it.
 
Sando said:
Hmmm, I thought 7mm was too much. However, most of the knives I found at japanesechefsknife.com were that size. Dude if you did a 60kg tuna with a 5mm.... well that's just too cool.

The western Tojiro looks more narrow too. Hmmm.... I think I'll stick with the more traditional shape and handle (but still double bevel).

BTW - Large mouth, most in the 1.5 to 2.5lb range. Of course there's the rare walleye for treats.

H Hubert S. Thanks, I found this video:
That Deba is over 7mm at the spine but, there is a bevel towards the edge. In other words, it's not 7mm where the edge bevel starts. Plus there's the hollow grind on the back. So that's gonna reduce weight too. The reviewer also mentions there's very little distal taper! That changes my dimensions quite a bit.

fitzo fitzo hahaha - Yeah, I'll be bringing the 20 year old fillet knife I made too. The kids usually fight over who gets to use it.
Click to expand...

I've done a couple of yo deba (double bevel/western deba) but in traditional profile, they are awesome to process fish with. A little slower than a traditional flexible fillet knife but increadibly clean cuts/fillets.

The single bevels do cut a little cleaner/easier with the more acute kireha but way more prone to chipping.

I've attempted one single bevel deba which was a fairly spectacular failier. They are a very complex grind.
 
Thanks N Nick-D . That's good to know. I'm surprised it's a little slower that a flexible fillet knife ... the youtube videos make it looks so easy! But that's probably more to do with being a professional than anything.

I found a bar of 0.219" MagnaCut and a 0.250" CPM-154. I'm sure both will work, just have to decide which.
 
Sando said:
Thanks N Nick-D . That's good to know. I'm surprised it's a little slower that a flexible fillet knife ... the youtube videos make it looks so easy! But that's probably more to do with being a professional than anything.

I found a bar of 0.219" MagnaCut and a 0.250" CPM-154. I'm sure both will work, just have to decide which.
Click to expand...
Yeah, as usual exceptions and caveats apply. For small to medium sized fish and your average filleter it will be similar speed. However once you are really proficient a flexible fillet knife is faster as you can work entirely from one side. With a deba general you work from both sides of the fish, so more cuts.

That said I do all my filleting with my various deba now as they are so easy to get clean fillets unless I have a big bin of fish to fillet then the old flexo comes out.

I spear and fillet a lot of large (15kg plus) kingfish (hamachi) and find the deba to be as fast if not faster on this size of fish.

Yo deba are also super usefull for hard use kitchen knife tasks as well so great to have in the quiver anyway.
 
Nick-D said:
Yeah, as usual exceptions and caveats apply. For small to medium sized fish and your average filleter it will be similar speed. However once you are really proficient a flexible fillet knife is faster as you can work entirely from one side. With a deba general you work from both sides of the fish, so more cuts.

That said I do all my filleting with my various deba now as they are so easy to get clean fillets unless I have a big bin of fish to fillet then the old flexo comes out.

I spear and fillet a lot of large (15kg plus) kingfish (hamachi) and find the deba to be as fast if not faster on this size of fish.

Yo deba are also super usefull for hard use kitchen knife tasks as well so great to have in the quiver anyway.
Click to expand...
How thick are your yo deba at the spine? I've looked at a few online and they seem to be a good bit thinner (~4mm) than the traditional ones (~7mm).
 
I think the western deba, or a yo deba is a good idea.

Every time I see a youtube video of someone making any kind of single bevel Japanese knife they take the short cut, and completely leave off the ura, and just keep the back side of the knife flat. Which might not be that big of a deal when cutting and slicing, though it will stick more.

The real problem with that comes when it's time to sharpen the blade. Not having that hollow there, means a lot more steel Is going to have to be grinded away. Not fun. If you've ever had to flatten, sharpen, and polish the back of a western chisel, it takes a lot more effort than a japanese chisel with a nice hollow on the back. Same deal for a kitchen knife, except I would imagine even worse.

My point is, if you don't plan to put an ura on the back. Definitely go with a double bevel design.
 
Thanks N Nick-D & H Hubert S. I took your advice. I decided to go with 5.3MM (0.210") for the spine (with MagnaCut).

My trouble now is coming up with dimensions I like for a double bevel. This is best I could come up with.
1657385388220.png

However, 0.170" before the edge is just way too thick, even if it is a scandi grind.

Blankblank Blankblank I guess I'll go traditional with a single bevel and, of course, the hollow ground back.

The blade is just about out of the tempering oven. Gonna have to decide quick.
 
Sando said:
Thanks N Nick-D & H Hubert S. I took your advice. I decided to go with 5.3MM (0.210") for the spine (with MagnaCut).

My trouble now is coming up with dimensions I like for a double bevel. This is best I could come up with.
View attachment 1865967

However, 0.170" before the edge is just way too thick, even if it is a scandi grind.

Blankblank Blankblank I guess I'll go traditional with a single bevel and, of course, the hollow ground back.

The blade is just about out of the tempering oven. Gonna have to decide quick.
Click to expand...
The yo deba I've been looking at appear to be mostly full-flat ground, many with a biased grind, e.g., 70/30. I saw one that appeared to be convex ground, but I haven't seen a double bevel like in your drawing.
 
Sando said:
Thanks N Nick-D & H Hubert S. I took your advice. I decided to go with 5.3MM (0.210") for the spine (with MagnaCut).

My trouble now is coming up with dimensions I like for a double bevel. This is best I could come up with.
View attachment 1865967

However, 0.170" before the edge is just way too thick, even if it is a scandi grind.

Blankblank Blankblank I guess I'll go traditional with a single bevel and, of course, the hollow ground back.

The blade is just about out of the tempering oven. Gonna have to decide quick.
Click to expand...
Yeah. If it's something as wear resistant as magnacut, that hollow with be extra important. Either way you go. Post some update pictures! I would love to see this thing.
 
Also. Just a suggestion. Kitchenknifeforums is my go to place for any information, or opinions on japanese kitchen knives. Lots of collectors, not as many makers as here. But a lot of people to give you references on the dimensions of the knives they own, and find to work well.

And keep in mind, I feel for the deba in particular it is very common for them to have quite a distal taper, and for the bevel to be more obtuse towards the heel, and transition to a more acute angle towards the tip, for hard chopping at the heel, and having the tip able to do fine cutting tasks.

Edit: also if you end up doing a double bevel look up takedas deba knives. They seem to be a good example of a normal sized deba, that is double beveled.
 
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Blankblank said:
Also. Just a suggestion. Kitchenknifeforums is my go to place for any information, or opinions on japanese kitchen knives. Lots of collectors, not as many makers as here. But a lot of people to give you references on the dimensions of the knives they own, and find to work well.

And keep in mind, I feel for the deba in particular it is very common for them to have quite a distal taper, and for the bevel to be more obtuse towards the heel, and transition to a more acute angle towards the tip, for hard chopping at the heel, and having the tip able to do fine cutting tasks.

Edit: also if you end up doing a double bevel look up takedas deba knives. They seem to be a good example of a normal sized deba, that is double beveled.
Click to expand...

Thanks for the website, very helpful to see traditional style with a double bevel. https://www.toshoknifearts.com/collections/takeda-deba

They are double beveled AND have a urasuki on one or both sides.

Hahahaha - Now I'm freaking out on all the options!

Here's a double bevel plan:

Keep 1/2" bevel down the length of the edge on both sides.

If the heel is 0.200" thick, then the bevel angle is 11 degrees (22 inclusive).

If I want 7 degrees (14 inclusive) near the tip, then it must distal taper down to 0.120" thick.
 
Sando said:
Thanks for the website, very helpful to see traditional style with a double bevel. https://www.toshoknifearts.com/collections/takeda-deba

They are double beveled AND have a urasuki on one or both sides.

Hahahaha - Now I'm freaking out on all the options!

Here's a double bevel plan:

Keep 1/2" bevel down the length of the edge on both sides.

If the heel is 0.200" thick, then the bevel angle is 11 degrees (22 inclusive).

If I want 7 degrees (14 inclusive) near the tip, then it must distal taper down to 0.120" thick.
Click to expand...
Seems good to me.
 
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Here is what I did in the course (ground by a very skillful teacher of the class and an awesome knifemaker Richard Kappeler).

Technique between fileting with deba and filet knife is completly different. With filet knife you are doing pull cuts and slicing off the bone, while with deba your are riding the bone but slicing through (push cut) anything that's on way, hard to describe. That's why I think that classic deba is superior (because it lays flat on the bone) but it needs more control and practice - don't led the YT vids fool you.

Anyway, everything above 2 kg you could try deba on as a novice, anything smaller I would go for a filet knife, or you risk leaving a lot of fish on the bone if you are not skilled enough.

If that happens and the fish is fresh, I would suggest you to try fish tartare. Scrape the rest meat from the bone with a spoon, mince it, add premium grade olive oil, salt and fresh pepper and the herb of you choice (IMHO either dill or thyme works best). Grill some white bread with butter and/or olive oil and dig in it.
 
Sando said:
FredyCro FredyCro Cool edge dimensions on that one. I understand what you're talking about. Yeah, I'm making too much knife for this small of fish. It'll be fun to see how it works out.
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I am going to leave this two links as the size of the fish might be appropriate, check the size of the knife, the difference in technique and the cleanliness of the cut.


 
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