Does this knife need thinning or sandpaper?

[Delat]

I can’t quite figure out if this knife needs thinning or if it’s the finish causing suction that makes it hang up on onions. In the first video you can see it gets stuck doing horizontal cuts on onions, and also sometimes on the vertical cuts. But in the second video it has no problems with a sweet potato.

At the midpoint immediately behind the edge at 1mm it’s .22mm which seems a bit thick. But higher up at 5mm it’s .44mm and at 10mm it’s 1.0mm, which seem reasonable. So the measurements don’t seem excessive except for immediately BTE.

So should I thin a bit, or try some sandpaper first - and if so what grit? It’s a convex grind, so I wouldn’t normally expect suction to be much of an issue.

FYI @Matt Jacobs

 

[refcast]

Try metal polish first, that usually does the trick

 

[Delat]

Try metal polish first, that usually does the trick

Like Flitz?

 

[tostadas]

Based off the dimensions, I'd bet on finish being the issue. I've had knives in the range of 0.25-0.3mm @1mm behind the edge that still did fine through dense stuff. P800 sandpaper is a good spot to test geometry because it's not too grippy (low grit), and not too sticky (high grit).

 

[Matt Jacobs]

That is interesting, it goes through the sweet potato so nicely. I think I had something similar with a Shiro Kamo damascus and it resolved after I ran the blade over a strop for a bit. I have another V-toku2 stainless clad knife that flies through everything but the stainless is polished so that could be part of the difference? It looks like it has to be more than just being too thick.

 

[Delat]

Based off the dimensions, I'd bet on finish being the issue. I've had knives in the range of 0.25-0.3mm @1mm behind the edge that still did fine through dense stuff. P800 sandpaper is a good spot to test geometry because it's not too grippy (low grit), and not too sticky (high grit).

I have a gap between p400 and p1000 so I’ll give the p1000 a try and see if it makes a difference.

Looks I’ll be making a batch of caramelized onions this weekend

 

[Delat]

That is interesting, it goes through the sweet potato so nicely. I think I had something similar with a Shiro Kamo damascus and it resolved after I ran the blade over a strop for a bit. I have another V-toku2 stainless clad knife that flies through everything but the stainless is polished so that could be part of the difference? It looks like it has to be more than just being too thick.

Yup I was sure it was going to wedge on the sweet potato so it immediately had me rethinking the whole thinning project I was planning.

 

[McMan]

I'm actually seeing decent food release (the cut that splits the onion) and the first few cuts on the sweet potato. With slow/deliberate cuts, sticking is more frequently an issue, especially because there is no upswing just downstroke (if that makes sense). Is stiction still an issue when cutting faster?

 

[HumbleHomeCook]

Based on my own experiences, what I'm seeing absolutely looks finish-driven and I agree with trying to slick it up a bit. I've encountered this multiple times.

Admittedly, I have limited experience compared to so many others but I think I've gotten more performance enhancements from a little edge shoulder relief and finish smoothing than any amount of actual thinning. Not at all saying thinning can't be important of course, just saying the jump forward in performance from the previous can be quite surprising.

 

[Delat]

I'm actually seeing decent food release (the cut that splits the onion) and the first few cuts on the sweet potato. With slow/deliberate cuts, sticking is more frequently an issue, especially because there is no upswing just downstroke (if that makes sense). Is stiction still an issue when cutting faster?

I tried a fast tip slice (horizontal) through the onion and it got stuck pretty quickly.

 

[Delat]

Based on my own experiences, what I'm seeing absolutely looks finish-driven and I agree with trying to slick it up a bit. I've encountered this multiple times.

Admittedly, I have limited experience compared to so many others but I think I've gotten more performance enhancements from a little edge shoulder relief and finish smoothing than any amount of actual thinning. Not at all saying thinning can't be important of course, just saying the jump forward in performance from the previous can be quite surprising.

Ok I think I have a plan! A low-angle relief bevel and a rub with p1000 sandpaper.

 

[Bolt Thrower]

is the apex sharp? could you shave with it? to me it just looked like it could use a touch up.

 

[drsmp]

Micro mesh pads have worked well for me on sticky Damascus with no noticeable downside to the look of the blade. Even with 1K sandpaper it’s easy to get hairline scratches

 

[Delat]

is the apex sharp? could you shave with it? to me it just looked like it could use a touch up.

I put a fresh edge on it to give it the best showing before taking the videos.

 

[Delat]

Micro mesh pads have worked well for me on sticky Damascus with no noticeable downside to the look of the blade. Even with 1K sandpaper it’s easy to get hairline scratches

Thanks, good to know. I think my lowest micro mesh grit is 1200, I’ll give it a try first.

 

[tostadas]

Thanks, good to know. I think my lowest micro mesh grit is 1200, I’ll give it a try first.

1200 micromesh is really scratchy. I don't know how it translates to sandpaper grit, but I think you might end up with a lot of visible scratches with 1200.

 

[Bear]

Thanks, good to know. I think my lowest micro mesh grit is 1200, I’ll give it a try first.

5000 grit trizact dry no water or try 0000 steel wool, I do prefer the trizact.

 

[Delat]

1200 micromesh is really scratchy. I don't know how it translates to sandpaper grit, but I think you might end up with a lot of visible scratches with 1200.

Ooooh, thanks for pointing that out! I just assumed it was the same grit scale as sandpaper.

https://micro-surface.com/grit-conversion/

 

[Delat]

Success! Thanks for the tips guys. I thinned immediately behind the edge, basically adding a 5 degree relief bevel. That took it down from .2mm to .1mm @1mm BTE.

As @tostadas warned, the lower micro mesh grits were indeed scratchy. I started at 2800 and worked my way up to 4000. The original finish was probably sandblasted as the sanding revealed all the belt sander marks. The blade now performs much better - not quite Myojin smooth so I think I’ll thin it more a bit higher up (it measures 1mm @10mm BTE, my Yoshi and Myojin are around .8mm) which will help me take out some of those sanding marks anyway.

It’s still a bit reluctant on the horizontal cuts, not quite sure if it’s thickness or stiction at this point but I’ll continue experimenting with both.

I should mention that the maker, Brian Hanson, is a former chef and this is his budget line of knives intended for professional use by line chefs. So the original thicker geometry is appropriate for that application. At $250 and with the 20 mins of tuning work I put in, I think it’s a terrific value for a Western maker especially for a pro cook.

Here’s the original OOTB finish.

Post-tuning, you can see my thinning for the first few mm BTE, and the post-sanding finish.

 

[Delat]

For anybody still following along, I dialed back the micro mesh finish to 3000 grit with noticeable improvement over the 4000.

Now I’m pondering if I want to drop down into the 2000 range and live with the resulting scratch pattern. The knife is incredible through thick carrots - very smooth without a single crack. So thickness is clearly fine at this point and probably was all along, but putting in the back bevel was fun anyway.

 

[mengwong]

How did your onions magically double in size in that short time

 

[Delat]

How did your onions magically double in size in that short time

LOL I got the biggest onions I could find to make it a hard test. Damn organic onions at $2/pound, the things we do for our hobbies.

Oh hey @mengwong, your @MSicardCutlery passaround is in the mail to me right now. Would you like a video of it on the same onion test?

 

[mengwong]

Yes please! If you feel the urge to resurface the finish to similar effect, do go ahead. Do the onion. The big onion.

 

[Matt Jacobs]

I have had really good luck with a coffee etch on V-toku2. You should be able to get the finish back pretty easily on that guy if you re-etch it after you are done tuning it.