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Sharpness test
- Thread starter DrHenley
- Start date
- Joined
- Jun 29, 1999
- Messages
- 9,733
Sharp is when you just wave it over the tomato and it obediently falls into even slices in terror.
Second, sharp is when you don't notice you've cut yourself until you see the blood.
Second, sharp is when you don't notice you've cut yourself until you see the blood.
Well hell, all of the knives I make can do that! That usuba in the two videos can push cut a green onion just from the weight of the knife, and it's a very light blade.sharp is when you can push cut the tomato
I'll have to make a video...
D
DrHenley
: Different yes, cheating no.
My tomato slicing test was done years before your own test, and it was also done with a ceramic knife instead of a steel one.
Also the tomato half & the grape half are resting on a thin layer of their own fluids, which makes it very easy to push them away instead of slicing through them.
This is very visible in the second clip when i make the apparent mistake of trying to cut a thicker slice, then the half tomato gets pushed away.
Slicing with one hand and trying to capture it with a camera in the other hand was not easy
So far i just never tried to slice a whole tomato the way you did, but i am quite sure that the Takamura R2 in the grape video could have done it.
The ceramic knife might have been even sharper, but also a bit thicker behind the edge, so i have my doubts about that one.
Now i do have a few custom Sabol Brothers gyuto's lying around that i still have to do some testing with, and buying some tomatoes is already on my list.
If i manage to shoot some reasonable footage it will be posted in this thread.
My tomato slicing test was done years before your own test, and it was also done with a ceramic knife instead of a steel one.
Also the tomato half & the grape half are resting on a thin layer of their own fluids, which makes it very easy to push them away instead of slicing through them.
This is very visible in the second clip when i make the apparent mistake of trying to cut a thicker slice, then the half tomato gets pushed away.
Slicing with one hand and trying to capture it with a camera in the other hand was not easy
So far i just never tried to slice a whole tomato the way you did, but i am quite sure that the Takamura R2 in the grape video could have done it.
The ceramic knife might have been even sharper, but also a bit thicker behind the edge, so i have my doubts about that one.
Now i do have a few custom Sabol Brothers gyuto's lying around that i still have to do some testing with, and buying some tomatoes is already on my list.
If i manage to shoot some reasonable footage it will be posted in this thread.
I was just kidding. Forgot to put a smiley face...
I've done it both ways, with a halved tomato and with a whole tomato and actually it didn't make that much difference.
BTW, that usuba is made from a bimetal industrial hacksaw blade that has a strip of tungsten carbide at the edge. Getting a refined edge is a bear since stropping doesn't really do anything. Bevel grind with a 15° single bevel, 20° micro bevel and 5° microbevel on the flat side. @10° it's insanely sharp but with practically zero edge stability. Plus it's damn near impossible to get a refined edge at 10° inclusive. Stropping just rolls the edge over to the other side.
I've done it both ways, with a halved tomato and with a whole tomato and actually it didn't make that much difference.
BTW, that usuba is made from a bimetal industrial hacksaw blade that has a strip of tungsten carbide at the edge. Getting a refined edge is a bear since stropping doesn't really do anything. Bevel grind with a 15° single bevel, 20° micro bevel and 5° microbevel on the flat side. @10° it's insanely sharp but with practically zero edge stability. Plus it's damn near impossible to get a refined edge at 10° inclusive. Stropping just rolls the edge over to the other side.
Many moons ago i did make a few choppers out of whole bimetal industrial (machine) hacksaw blades which used strips of HSS steel for the teeth (my brother still owns one), but i never saw them with tungsten carbide strips.
Also made a few knives out of full hard M2 high speed steel machine hacksaw blade @ 65-66, like this one:
Did you sharpen the tungsten carbide in your knife with CBN and/or diamond or with other abrasives ?
Also made a few knives out of full hard M2 high speed steel machine hacksaw blade @ 65-66, like this one:
Did you sharpen the tungsten carbide in your knife with CBN and/or diamond or with other abrasives ?
Diamond mostly. I was able to wear them down a bit with carborundum and Akansas stones, polish them more like it, LOL. It took many hours to put an edge on it, and I wore out several diamond stones and an angle grinder grinding disc. Belt sander was no use. I used the angle grinder to flatten the teeth, and by the time they were flat the disc was worn down smooth and wouldn't cut very well and although I tried for a while to use it to put a bevel on the edge, I finally gave up because I wasn't getting anywhere. A 200 grit diamond stone cut it pretty well though.
I got these hacksaw blades from my next door neighbor decades ago. I have looked online and I can't find any like them now. All the bimetal blades have tool steel teeth now. I still have two more...
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A 120 grit Chinese diamond file would probably work well to put an initial edge on that tungsten carbide strip.
These files are quite cheap, yet have a surprisingly long life span.
Bought mine on the bay, and i'm thinking about buying a few more in different grits.
The red plastic handles are useless though, much too small and also made from inferior plastic.
I threw it away and use my diamond file without a handle.
These files are quite cheap, yet have a surprisingly long life span.
Bought mine on the bay, and i'm thinking about buying a few more in different grits.
The red plastic handles are useless though, much too small and also made from inferior plastic.
I threw it away and use my diamond file without a handle.
a very good sharpness test is cutting tomato (skin) at 100% perpendicular angle and without pressure whatsoever.
slicing through a tomato at an angle other than 90degree AND with slicing motion AND with some pressure isn't too challenging.
try 90.0degree, no pressure, only ⅛th of an inch slicing motion! if your edge doesn't cut the tomato skin under this condition triplet, go back to your stones and try apexing again!
this test result is even more revealing and impressive than the flashlight\apex\reflection trick. it gives the final PASS.
slicing through a tomato at an angle other than 90degree AND with slicing motion AND with some pressure isn't too challenging.
try 90.0degree, no pressure, only ⅛th of an inch slicing motion! if your edge doesn't cut the tomato skin under this condition triplet, go back to your stones and try apexing again!
this test result is even more revealing and impressive than the flashlight\apex\reflection trick. it gives the final PASS.
I doht have a video of the tomato-perpendicular-cutting because my edges aren't that sharp (but ex-factory they were!).
anyway D DrHenley can you confirm/admit that cutting tomato skin at 0° with respect to its normal is truly challenging? Maybe you have a semi-sharp EDC knife lying around to test the angle factor.
(but ex-factory they were!).anyway D DrHenley can you confirm/admit that cutting tomato skin at 0° with respect to its normal is truly challenging? Maybe you have a semi-sharp EDC knife lying around to test the angle factor.
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Not really following you kreisler. Try again on the video and this time cut the tomato so I'll know what you are talking about.
Meanwhile here is a video I did for a review of the Pioneer Woman Cowboy Rustic Chef's Knife (Wusthof Classic clone) where I slice a tomato using just the weight of the knife. Is this what you mean by "zero pressure"? There has to be something making the knife move (like gravity) which will then exert pressure on the tomato. This knife is only half as sharp as the usuba in my previous video.
Meanwhile here is a video I did for a review of the Pioneer Woman Cowboy Rustic Chef's Knife (Wusthof Classic clone) where I slice a tomato using just the weight of the knife. Is this what you mean by "zero pressure"? There has to be something making the knife move (like gravity) which will then exert pressure on the tomato. This knife is only half as sharp as the usuba in my previous video.
Yes your clip demonstrates (more or less) what i meant with "90°" angle, and i can tell that the knife is scary sharp. Kitchen knives are easier to get scary sharp. I don't question at all your sharpening skills and results, don't worry. Am just saying that cutting a tomato at an angle is easier for a knife edge to do. you can see this 'phenomenon' at 03:31-03:33 where the guy tries to cut at 90°; a scary sharp edge would have passed this short test.
- Joined
- Oct 30, 2010
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- 2,109
I like the grape drop. That is just KOOL!
Because the supermarket only carries tomatoes, not CATRA machines.
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