Just wrapped up some testing on hollow ground chef knives vs. flat ground chef knives. interesting results . . . Peak power requirements for hollow ground knives are on shoulder entry as you stated. - Most evident on high density brittle foods like carrots. Peak power requirements for flat ground knives are just about 1/4" ( 6mm) prior to exit. Medium density foods like a the softer Irish/red/white potatoes & onions is where hollow ground blades can equal & sometimes even out perform thin flat ground knives by single digit percentages. Properly thinning a flat ground chef's knife can consume more than an hour even with a nice 2 x72 belt grinder & fresh belts. Thanks for all that you share... More test data has arrived in your e-mail.
Thanks man - this is fascinating!!! I will get back to the email as soon as I can - that data all checks out with my observations, but it's awesome to have some numbers. Thanks for all you do sir!
Yeah, I can understand that. I think you are right that the gains in BESS are not because of the grind. However, I think that human hand angle variance makes it difficult for me to maintain a steady angle for the many refining strokes needed to remove all damaged metal in a larger/thicker edge by hand and I usually under-do burr removal slightly or over-round the apex slightly. What this allowed me to do is minimize strokes on the stone and strops to maximize accuracy because the edge surface was only a few tenths of a millimeter wide, resulting in a better BESS score than I often get. It also helps that I micro-beveled at 15 dps rather than my usual 17 dps, and angle does help with BESS as long as full deburring has occurred. Hopefully that makes sense, but you make a valid observation. The edge surface would have to have a width smaller than the diameter of the BESS test line for the grind to have any ultimate effect on BESS score.
@@homeslicesharpening Great analysis. I take a lot of inspiration from your testing and incorporate it into my own tinkering. Keep doing what you're doing.
Vinny Nero (neroknives) has videos showing him doing this with his Spyderco Southard. Edit: ...apparently he privated all his videos. He had a few of my favorite videos; pulling nails with an s110v pm2, prying apart 2x4s with a sebenza and just great general knife theory. Im sure the 3 other people who have been in the hobby for 10+ years remember him.
Haha - I have been in the hobby since Murray Carter opened his shop for public viewing back in 2012! That's cool that he tried it as well, but bummer his videos are pulled now. Cheers!
Woohoo,, Inkosi here I come,, ha ha, I've "knocked off" the "shoulders" on nearly every secondary bevel, ffg blade, for years,, imho, it Improves the slicing capabilities a massive amount,, 👍🇬🇧
@@homeslicesharpening Yes, I was mostly kidding, lol,, my new Inkosi came with an extremely good edge, (Magnacut), so I'll wait a good while before summoning up the courage to change anything on it, ha ha, (it's just too beautiful,,) ps, we've a lot of furniture due today, and I've already put a good edge on my trusty Spyderco ukpk, so I can keep the Inkosi pristine, ha ha ha,, all the best from West Yorkshire, 🇬🇧
That looks rather nice with the mirrored bands. I can’t help but wonder how a CPM CruWear Yojimbo might behave with a similar treatment 🤔 (a knife I use a lot for tree grafting but little else because of it getting wedged in deeper cuts).
I love it! And the reprofiling only took you about an hour? It'd definitely be a lot longer on any full flat ground blades, like you said. I attempted something similar with a Böker Kwaiken 7 or 8 years ago, but because they're relatively thick both behind the edge and at the shoulder (and I didn't have quite the same sharpening materials at my disposal), I may have lost my patience and settled for a more obtuse (albeit still improved) geometry. If someone doesn't need the profile QUITE so keen, and wants to save a little time, one can always angle the blade so the shoulder just clears the stones but still removes a lot of material behind the edge. I've done this with a Buck 117 and Civivi Ortis. I can't say they're as hair whittling sharp as your Buck here, but there's a definite improvement.
Interesting! Yeah, if someone wanted to mimic this minus the modification of aesthetic and removal of grind shoulder you could just wrap the shoulder of the hollow grind in masking tape, and lay down the blade. Everything else would clear the stone's abrasives (not get scratched), and you could simply reprofile most of the edge to the angle between grind shoulder and apex (usually 2-5 degrees per side) and just leave a small micro-bevel.
@@homeslicesharpening There's gotta be some technique to it... the couple of times I've used masking tape during sharpening, I just end up chewing through the tape 😓
I'd reckon that convexing a full flat grind is analogous to flat-grinding a hollow in terms of only grinding the upper and lower shoulders of the main bevel, but matching the radius of the convex to the height of the blade is a lot trickier than just putting a concave blade on a flat stone.
We used to hollow grind our boning knives in the freezing works gabe. I have always wondered how the same knive would perform with your half / half coarse / fine edge.🤔🤔🤔 would love to see that video. Use just a cheap victory boning knife. They are german steel. Proberly the most respected brand at the moment.😝👊🔪🔪🔪💯💯💯
Interesting idea! So you would do a hand regrind to the NZ "Victory" brand boning knives to help with tasks? What is the freezing works? Thanks for the interesting comment man, always good to hear from you Jason.
The "rate of thickening" is what i always talked about with the 10dps (or even lower) transition bevel for FFG. Makes a drastic difference in cutting. And yes i also always flat the heights of a hollow grind, its the best combination of cutting performance and thinning time. Nice your going in the direction of efficient geometry testing, was waiting for it. 😉👍The time of a new era has come. 🫢 And as you can see, way easier to resharpen too, even reaching higher quality. The BESS numbers i mentioned should seem more realistic to you with this method, as you can easely reach them now. 😊 Testing video series idea: 1. How large does the 15dps microbevel has to be, for different tasks? (Basically, how large is edge damage actually.) 2. How does the transition bevel angle behind it affect it / prevents deflection? (Im most interested in magnacut results, as its the most well balanced steel.) This is a topic i always wanted to cover in videos but never found the time. Many people dont realize how thin and well cutting their knive could actually be, microbevel size depends on damage size of the task, and damage is often WAY smaller than people think, except for very unstable steels.
Yeah - I think I was inspired to try this partially out of my old conversations with you and my friend Jason. It is incredible the performance advantage you unlock!!! Unfortunately, I don't have a lot of hollow ground knives, but this is amazing enough I'm going to have to find some and invest! I think Pete is going to hook me up with a Quiet Carry Waypoint which would be darn near perfect, and I'll probably end up doing this to the Sebenza I ordered in MagnaCut. In any case, I think I have a little steel analysis left and some reviews of stuff I need to get done, but this thinned-out hollow grind is probably where my future sharpening and EDC priority is going in the years to come! Thanks for being patient! You were right, lol. You need to catch the next episode if possible, this Buck outperforms some SPY27 and is still stropping back to whittling hair after almost 3 weeks!!!
The one thing I dont really like with hollow grinds is that for some reason they seem to walk a bit in the cut, making it harder to cut straight. If its actually symmetrical it shouldnt, but it seems to do regardless. Whether thats down to it not being perfectly even or just the geometry making it prone to changing directions I have no idea, but to me that affects the feel of cutting. Then again I might just be a weirdo and noone else in the world have that problem.
No- I've experienced that as well. I think it's the way the edge creates compression as it goes through, then compression is released by the grind thinning out, but often one side of the blade is against a firm surface (like if you are peeling an apple, as the compression releases, one side is against the resistance of the apple itself, one is just against the peel creating a pressure difference side-to-side). I think this thinning I did solved that problem for me.
@@homeslicesharpening Interesting! I feel like this is getting dangerously close to honbazuke and Japanese S grinds but at the same time different enough that I have no idea what it does. Sure seems to do something though! I wanna try that too now haha
Kinda! I have now heard it referred to as an S-grind. It's sort of like if you had a high scandi and took a round wheel and hollowed out the shoulder. Very slicey!
Murry carter talked about this regarding hollow grinds and specifically mentioned buck knives benefiting from this type of sharpening
Fascinating!!! I love Murray! Thanks for sharing!
Just wrapped up some testing on hollow ground chef knives vs. flat ground chef knives.
interesting results . . .
Peak power requirements for hollow ground knives are on shoulder entry as you stated.
- Most evident on high density brittle foods like carrots.
Peak power requirements for flat ground knives are just about 1/4" ( 6mm) prior to exit.
Medium density foods like a the softer Irish/red/white potatoes & onions is where
hollow ground blades can equal & sometimes even out perform thin flat ground
knives by single digit percentages.
Properly thinning a flat ground chef's knife can consume more than an hour even
with a nice 2 x72 belt grinder & fresh belts.
Thanks for all that you share... More test data has arrived in your e-mail.
Thanks man - this is fascinating!!! I will get back to the email as soon as I can - that data all checks out with my observations, but it's awesome to have some numbers. Thanks for all you do sir!
Great home knife science! Thanks for sharing
No worries! It's tested next week with some stunning results!
Very interesting Gabe....ihave a couple of hollow ground blades hanging around, so i might give it try
Man, you should try it. I am not kidding, this thing stropped back to whittling hair for nearly 3 weeks, it was insane!
Cool little project. Yet, I don't think that the new geometry would have any influence on the Bess rating, as it's only testing apex sharpness.
Yeah, I can understand that. I think you are right that the gains in BESS are not because of the grind. However, I think that human hand angle variance makes it difficult for me to maintain a steady angle for the many refining strokes needed to remove all damaged metal in a larger/thicker edge by hand and I usually under-do burr removal slightly or over-round the apex slightly.
What this allowed me to do is minimize strokes on the stone and strops to maximize accuracy because the edge surface was only a few tenths of a millimeter wide, resulting in a better BESS score than I often get.
It also helps that I micro-beveled at 15 dps rather than my usual 17 dps, and angle does help with BESS as long as full deburring has occurred.
Hopefully that makes sense, but you make a valid observation. The edge surface would have to have a width smaller than the diameter of the BESS test line for the grind to have any ultimate effect on BESS score.
@@homeslicesharpening Great analysis. I take a lot of inspiration from your testing and incorporate it into my own tinkering. Keep doing what you're doing.
Looks amazing brother
She cuts pretty good tooooo!!!
Vinny Nero (neroknives) has videos showing him doing this with his Spyderco Southard.
Edit: ...apparently he privated all his videos. He had a few of my favorite videos; pulling nails with an s110v pm2, prying apart 2x4s with a sebenza and just great general knife theory.
Im sure the 3 other people who have been in the hobby for 10+ years remember him.
Haha - I have been in the hobby since Murray Carter opened his shop for public viewing back in 2012! That's cool that he tried it as well, but bummer his videos are pulled now.
Cheers!
I learned a lot from neroknives' videos, he's the first knife UA-camr I remember talking about BTE thickness.
Interesting. Thanks for experimenting and sharing 💪🏻👍🏻
No problem, have a great day!
Commonly called an S grind. It’s quite common on higher end custom kitchen knives. Usually it’s a convex edge with a hollow for food release.
Oh interesting - thanks Kyle, that is so cool to know!
Woohoo,, Inkosi here I come,, ha ha,
I've "knocked off" the "shoulders" on nearly every secondary bevel, ffg blade, for years,, imho, it Improves the slicing capabilities a massive amount,, 👍🇬🇧
True! That's awesome. I am seriously considering doing this on the Sebenza I just got, but will probably try it out as-is first!
@@homeslicesharpening
Yes, I was mostly kidding, lol,, my new Inkosi came with an extremely good edge, (Magnacut), so I'll wait a good while before summoning up the courage to change anything on it, ha ha, (it's just too beautiful,,)
ps, we've a lot of furniture due today, and I've already put a good edge on my trusty Spyderco ukpk, so I can keep the Inkosi pristine, ha ha ha,, all the best from West Yorkshire, 🇬🇧
Very cool!
Thanks man, let me know if you try it!
That looks rather nice with the mirrored bands. I can’t help but wonder how a CPM CruWear Yojimbo might behave with a similar treatment 🤔 (a knife I use a lot for tree grafting but little else because of it getting wedged in deeper cuts).
You should try it!!!
I love it! And the reprofiling only took you about an hour? It'd definitely be a lot longer on any full flat ground blades, like you said. I attempted something similar with a Böker Kwaiken 7 or 8 years ago, but because they're relatively thick both behind the edge and at the shoulder (and I didn't have quite the same sharpening materials at my disposal), I may have lost my patience and settled for a more obtuse (albeit still improved) geometry.
If someone doesn't need the profile QUITE so keen, and wants to save a little time, one can always angle the blade so the shoulder just clears the stones but still removes a lot of material behind the edge. I've done this with a Buck 117 and Civivi Ortis. I can't say they're as hair whittling sharp as your Buck here, but there's a definite improvement.
Interesting! Yeah, if someone wanted to mimic this minus the modification of aesthetic and removal of grind shoulder you could just wrap the shoulder of the hollow grind in masking tape, and lay down the blade.
Everything else would clear the stone's abrasives (not get scratched), and you could simply reprofile most of the edge to the angle between grind shoulder and apex (usually 2-5 degrees per side) and just leave a small micro-bevel.
@@homeslicesharpening There's gotta be some technique to it... the couple of times I've used masking tape during sharpening, I just end up chewing through the tape 😓
I'd reckon that convexing a full flat grind is analogous to flat-grinding a hollow in terms of only grinding the upper and lower shoulders of the main bevel, but matching the radius of the convex to the height of the blade is a lot trickier than just putting a concave blade on a flat stone.
Hmmm, that's interesting! You are probably right!!!
We used to hollow grind our boning knives in the freezing works gabe. I have always wondered how the same knive would perform with your half / half coarse / fine edge.🤔🤔🤔 would love to see that video. Use just a cheap victory boning knife. They are german steel. Proberly the most respected brand at the moment.😝👊🔪🔪🔪💯💯💯
Interesting idea! So you would do a hand regrind to the NZ "Victory" brand boning knives to help with tasks? What is the freezing works? Thanks for the interesting comment man, always good to hear from you Jason.
We Had Different Brands Of Knives At Different Times.
The "rate of thickening" is what i always talked about with the 10dps (or even lower) transition bevel for FFG. Makes a drastic difference in cutting.
And yes i also always flat the heights of a hollow grind, its the best combination of cutting performance and thinning time.
Nice your going in the direction of efficient geometry testing, was waiting for it. 😉👍The time of a new era has come. 🫢
And as you can see, way easier to resharpen too, even reaching higher quality.
The BESS numbers i mentioned should seem more realistic to you with this method, as you can easely reach them now. 😊
Testing video series idea:
1. How large does the 15dps microbevel has to be, for different tasks? (Basically, how large is edge damage actually.)
2. How does the transition bevel angle behind it affect it / prevents deflection?
(Im most interested in magnacut results, as its the most well balanced steel.)
This is a topic i always wanted to cover in videos but never found the time.
Many people dont realize how thin and well cutting their knive could actually be, microbevel size depends on damage size of the task, and damage is often WAY smaller than people think, except for very unstable steels.
Yeah - I think I was inspired to try this partially out of my old conversations with you and my friend Jason. It is incredible the performance advantage you unlock!!! Unfortunately, I don't have a lot of hollow ground knives, but this is amazing enough I'm going to have to find some and invest!
I think Pete is going to hook me up with a Quiet Carry Waypoint which would be darn near perfect, and I'll probably end up doing this to the Sebenza I ordered in MagnaCut. In any case, I think I have a little steel analysis left and some reviews of stuff I need to get done, but this thinned-out hollow grind is probably where my future sharpening and EDC priority is going in the years to come!
Thanks for being patient! You were right, lol. You need to catch the next episode if possible, this Buck outperforms some SPY27 and is still stropping back to whittling hair after almost 3 weeks!!!
The one thing I dont really like with hollow grinds is that for some reason they seem to walk a bit in the cut, making it harder to cut straight. If its actually symmetrical it shouldnt, but it seems to do regardless. Whether thats down to it not being perfectly even or just the geometry making it prone to changing directions I have no idea, but to me that affects the feel of cutting. Then again I might just be a weirdo and noone else in the world have that problem.
No- I've experienced that as well. I think it's the way the edge creates compression as it goes through, then compression is released by the grind thinning out, but often one side of the blade is against a firm surface (like if you are peeling an apple, as the compression releases, one side is against the resistance of the apple itself, one is just against the peel creating a pressure difference side-to-side).
I think this thinning I did solved that problem for me.
@@homeslicesharpening Interesting! I feel like this is getting dangerously close to honbazuke and Japanese S grinds but at the same time different enough that I have no idea what it does. Sure seems to do something though! I wanna try that too now haha
@@homeslicesharpening That would make alot of sense!
How many minutes did it take you to do this grinding on the blade of this buck?
About one hour
Yeah, it was roughly an hour!
So you made it a scandi grind.
Kinda! I have now heard it referred to as an S-grind. It's sort of like if you had a high scandi and took a round wheel and hollowed out the shoulder. Very slicey!