Thinning...?

[ModRQC]

You have to remember that these blades are first made, and they don’t come out perfect as they’re sold, they’re worked into it. Any finish on any knife is reproducible, but as you don’t have all their tools, sometimes you chose the simplest way that looks nice enough. Now if you can’t refrain from turning the knife all angles under direct light and be disappointed with your work, you’re not gonna get through this, but the deal is to look nice enough under most settings, and be better performers.

edit: or, as @M1k3 said.

 

[Kippington]

When I sharpen I concentrate on removing as little metal as possible to keep the need for thinning down. Things like not trying to go for a honking great big burr down the entire length of the edge.
Sometimes I'll do a tiny bit of shoulder rounding but I generally only thin every 10 sharpenings or so. I have a belt grinder for that.

But I'd say more than 50% of J-Knives I've met so far needed thinning.

Before my morning coffee I read this as "500% of J-Knives I've met so far needed thinning" and it blew my mind.

 

[ModRQC]

@HumbleHomeCook ... if you'll forgive me for bringing your attention to this post...

Here's a Masahiro VC - carbon monosteel, and like any monosteel, a pain to re-finish so I do a botchy sandpaper job after thinning, whatever makes the deeper scratches fade most quickly to my eye goes...

because I know I'm gonna etch the full blade and have it look like this, with naturally blackened spots, and just looking like a patina of old:

Here's a Takayuki Damascus... One thing with a Tsuchime finish generally is that any scratch into it can be blended quite easily with sandpaper, since the surface is rougher to start with.

The Damascus layers were re-finished to high sandpaper grit, decent mirror finish, but I went quite fast about it... and I re-etched, not even using something strong like ferric chloride, but simple vinegar, which takes more time and is less spectacular. Under some angles, you can see the sandpaper scratches, and you can see the unevenness of the mirror polish I gave...

But under most settings...

And then again here's a Deep Impact... used the Cerax 320 to give a bevel finish... but as there were a lot of scratches upward of it, I taped off the bevel and gave a migaki-like finish with sandpaper, not going as fine as with the Takayuki for instance.

In the beginning I was scared of even having the tiniest of scratches from regular use. Then the necessity to work on my blades got me over that, but I was wasting a lot of time still not being satisfied, and not working correctly. I learned what goes, and what doesn't work so well. Now I kind of "botch" the jobs to the easiest way that looks okay, and keep happy.

And now, do you know what insults me most about a blade I need to refinish?

Those with stamped logo/kanji that you cannot save through a sandpaper progression. The only thing I don't like is removing the branding of a knife that's of value to me - even if that's a Victorinox. I still live with it. All my Victos are without logos but God do they cut to my likings. And I love J-knives that have a decently stamped engraving or truly engraved Kanji just because of that: you can refinish them all the way, and keep the maker's mark. It defines pretty well cheap knives from better one - those that have stamps which will vanish after a course of sandpaper, and those who live through many courses of sandpaper, and sometimes even look better when they become super polished by repetitive courses, making the stamp/engraving come out super nicely.

 

[Robert Lavacca]

Pfffttt. My masahiro looks wayyyyy better

I hated that knife at first. Bought for a real beater. I’ve beaten the **** out of that thing and it still is going strong. After I thinned the crap out of mine it cut so much better, easier to sharpen, and stays sharp. I even use a ceramic steel on it at work to keep the edge going. I love that thing now haha.

 

[Kippington]

Pfffttt. My masahiro looks wayyyyy better

I hated that knife at first. Bought for a real beater. I’ve beaten the **** out of that thing and it still is going strong. After I thinned the crap out of mine it cut so much better, easier to sharpen, and stays sharp. I even use a ceramic steel on it at work to keep the edge going. I love that thing now haha.

Yeah those scuffs and scratches signify that the knife has been worked behind the edge, and it often indicates that a knife has been better looked after over one that still has shiny or factory finished surfaces.

I'm happy to have my personal knives looking like they've lost a fight with a pavement, so long as the knife performs how I want it. This one had no etch, it's just what the stone slurry did to the pattern.

Admittedly, with a bit of skill you can get even better results off a belt grinder, even at the same low grit.

 

[user 37848]

Admittedly, with a bit of skill you can get even better results off a belt grinder.

Any tips on getting a nice uniform factory finish like you did w the HD here? You can PM me if it's not too much trouble, I don't want to derail the thread

 

[Kippington]

It's simply running a slack belt down the surface. You can mess up the knife if you do it wrong, so there's definitely some steady-handed technique involved.
It's not my picture by the way, just an example of what it looks like.

 

[user 37848]

Ok thats what I was doing some results better than others. Thought there was some magic technique haha

Thanks

 

[CA_cook]

How far from the edge do you thin? Can you do it on regular stones? Why not just do an additional sharpening step at a very low angle, would that give an essentially same result?

 

[ModRQC]

KKF science says: 0.2mm just above the edge, 0.5mm at 5mm from the edge, 1mm at 10mm from the edge.

Yes regular stones - coarser ones not to spend a day on it.

As for your last question it's been discussed a lot in this very thread, read carefully - see "relief bevel" and @Leo Barr pic.

 

[ian]

If you care what your knives look like, you shouldn't thin with every sharpening, since then you'll scratch them up, and you def don't want to refinish every time. (Unless we're talking wide bevels.)

Otherwise, do what you want. I don't thin every time. I'd rather just sharpen until it's a problem, then deal with it.

I usually use 1000/2000 sandpaper with wood cork to clear the scratch from thinning everytime. Properly less than five minutes.

I suppose it's a good point that if you want a sandpaper finish and you are maintenance thinning on stones that are higher grit than your finish, it doesn't take long at all to refinish after thinning. I guess I was mainly thinking of fancier finishes, which take longer to reproduce. F**k, I like to think of myself as a hardcore user that doesn't care what his knives look like, but I think that may not be the case.

I think the real answer here, though, is that I never really do maintenance thinning on my own knives. I often do significant thinning when I receive a knife, but once I get it into a good shape, I always end up selling it before I need to thin it again. No knife ever stays with me for more than a few months of home use. On customer knives, I will thin if it needs it, and then do a quick sandpaper finish, or a nicer finish if it's a nicer knife.

It's simply running a slack belt down the surface. You can mess up the knife if you do it wrong, so there's definitely some steady-handed technique involved.
It's not my picture by the way, just an example of what it looks like.

I always liked the spine to edge belt finish on Gingas, too. Looks nice in person.

 

[happy_c]

Not sure if it's board etiquette to revive an old thread, but here goes anyway. As a newbie, I'm confused by the terminology related to thinning. From reading this thread and others, I'm getting the impression that proper blade geometry involves *three* bevels: The blade road below the shinogi line, which you thin every few years when it gets very thick; then another bevel below that, which you thin when doing "maintenance thinning" or "thinning behind the edge"; and finally another bevel below *that*, which you work on when "sharpening." Is this right, or am I grossly misunderstanding?

Sorry for any missteps in terminology, I'm still learning.

 

[ian]

Not sure if it's board etiquette to revive an old thread, but here goes anyway. As a newbie, I'm confused by the terminology related to thinning. From reading this thread and others, I'm getting the impression that proper blade geometry involves *three* bevels: The blade road below the shinogi line, which you thin every few years when it gets very thick; then another bevel below that, which you thin when doing "maintenance thinning" or "thinning behind the edge"; and finally another bevel below *that*, which you work on when "sharpening." Is this right, or am I grossly misunderstanding?

Sorry for any missteps in terminology, I'm still learning.

Not all blades have a shinogi line or really distinct bevels at all. Sometimes the blade face is continuously convex all the way from the spine to the edge, except for a small microbevel at the edge. The distinction between maintenance thinning and repair thinning largely depends on personal preference. Imo, knives with a shinogi (“wide bevel knives”) work best when below the shinogi there’s a slight convex (“hamaguri”) blade face that terminates in a microbevel at the edge. To avoid making the microbevel a macrobevel, one thins the entire blade below the shinogi regularly, if not every time it’s sharpened, which is the traditional way. On knives without a shinogi, some people even do “maintenance thinning” over most of the blade every time they sharpen, aesthetics be damned.

 

[ModRQC]

Take a basic geometry like a straight V-grind and you basically have two bevels; the faces going all the way down to the edge, and the edge bevel itself, assuming it’s not a zero grind.

Now a wide bevel: two bevels still, the V under the shinogi, and the edge bevel, assuming no zero grind. The faces in this case are no bevels per say.

Convex grind is the same: it could basically be thought like the V grind.

Maintenance thinning is what you can do as you progressively lose height in sharpening, thus bringing the edge up in the thicker part which you correct as you go; thinning is that it’s already quite too thick behind the edge and you need to remove more material - either an old knife never cared for properly (ie maintenance thinning), or any knife too thick from the start.

 

[Blank Blades.]

I do my maintenance thinning on the blade road. If you only thin right behind the edge, you will end up with a really jacked up geometry.

 

[happy_c]

Thanks for the replies. I'm way too much of a noob to think about convexing and such, but it sounds like that if I want to thin my knife (which I do--25 years old and never been thinned, maintenance or otherwise, in all that time), I should aim to thin it all the way from the shinogi line down to the bevel of the cutting edge, right? If so, is there a way to avoid inadvertently rubbing out the shinogi line? I really want better performance but I'm worried about screwing up.

Edit: I've watched videos on thinning, including this one and others, but despite their high quality I cannot seem to wrap my head around exactly what should be going on.

 

[ian]

Thanks for the replies. I'm way too much of a noob to think about convexing and such, but it sounds like that if I want to thin my knife (which I do--25 years old and never been thinned, maintenance or otherwise, in all that time), I should aim to thin it all the way from the shinogi line down to the bevel of the cutting edge, right? If so, is there a way to avoid inadvertently rubbing out the shinogi line? I really want better performance but I'm worried about screwing up.

Yes. Just keep the knife from wobbling when you’re working close to the shinogi and you’ll be fine. Keep finger pressure on the blade at all times and the geometry of the blade should prevent you from rounding the shinogi.

 

[Blank Blades.]

Thanks for the replies. I'm way too much of a noob to think about convexing and such, but it sounds like that if I want to thin my knife (which I do--25 years old and never been thinned, maintenance or otherwise, in all that time), I should aim to thin it all the way from the shinogi line down to the bevel of the cutting edge, right? If so, is there a way to avoid inadvertently rubbing out the shinogi line? I really want better performance but I'm worried about screwing up.

Edit: I've watched videos on thinning, including this one and others, but despite their high quality I cannot seem to wrap my head around exactly what should be going on.

Look up knifewear friday livestream with naoto. He does the entire thinning from beginning to end on camera, including polishing and everything. I'll link a good one in a sec. I recommend watching them live too, so you can ask him any questions you may have. Me and @HumbleHomeCook watch most of their streams. Very informative.

Edit

 

[happy_c]

Yes. Just keep the knife from wobbling when you’re working close to the shinogi and you’ll be fine. Keep finger pressure on the blade at all times and the geometry of the blade should prevent you from rounding the shinogi.

Ah, if only my hand were as steady as I like to think it is …
I’ve got a couple of cheap knives I’ve been practicing in. Will probably try thinning one of them before I take a stone to the knife I’m attached to. They don’t have shinogis, though …

 

[happy_c]

@jwthaparc , thanks for the tip. Would this one be a good place to start?

 

[Blank Blades.]

@jwthaparc , thanks for the tip. Would this one be a good place to start?

I linked that and one of the streams. Watch the short one first. If you need more information, watch the stream I linked. Like I said I also highly recommend watching live so you can ask questions as he does it. They stream every friday. I want to say 5pm central time.

 

[captaincaed]

Ah, if only my hand were as steady as I like to think it is …
I’ve got a couple of cheap knives I’ve been practicing in. Will probably try thinning one of them before I take a stone to the knife I’m attached to. They don’t have shinogis, though …

Starting cheap is the way to go, and taking little bites of the project, 20-30" per night, don't rush it. Ideally buy a new knife from your favorite retailer so you have one in the kitchen while you're doing the work! hehehe.
Also, use a ~220 grit stone. Anything finer is too slow. The extra time you spend translates into fatigue, and then wobble. It feels like crap, but it's quicker and easier to clean up later than you might think.

 

[Blank Blades.]

Also, use a ~220 grit stone. Anything finer is too slow. The extra time you spend translates into fatigue, and then wobble. It feels like crap, but it's quicker and easier to clean up later than you might think.

Yeah. My favorite for thinning was my shapton 120. Now I use my manticore. talk about removing material. It's a 60 grit, silicon carbide waterstone. Now most of the time I spend is just polishing it back up.

 

[captaincaed]

Yeah, for heavy work, go coarse. Some knifemakers talk about starting with 36 grit belts for rough shaping.

 

[happy_c]

I actually read in another thread that past a certain point, it’s hard to thin adequately without power tools to speed things up. I’ll see if I can get hold of a 220 grit stone, though. But won’t that scratch up the blade path terribly? Or do you go through the whole grit progression when you thin, same as for sharpening, before you refinish with sandpaper?

 

[HumbleHomeCook]

I actually read in another thread that past a certain point, it’s hard to thin adequately without power tools to speed things up. I’ll see if I can get hold of a 220 grit stone, though. But won’t that scratch up the blade path terribly? Or do you go through the whole grit progression when you thin, same as for sharpening, before you refinish with sandpaper?

If you want it to look nice you're going to have to go through a full progression. You might have to use "finger stones" or high grit sandpaper.

Fortunately, I value function over form.

 

[HumbleHomeCook]

I actually read in another thread that past a certain point, it’s hard to thin adequately without power tools to speed things up. I’ll see if I can get hold of a 220 grit stone, though. But won’t that scratch up the blade path terribly? Or do you go through the whole grit progression when you thin, same as for sharpening, before you refinish with sandpaper?

Also something to be aware of is soooooo many knives are not actually flat. They look flat but once you start rubbing them over an abrasive the hills and dips become readily apparent. It many cases it just isn't feasible to try to fully even everything out so I reckon that's where the finger work comes in for aesthetics.

 

[Kiru]

I remember someone said to me it depends what kind of lazy you are, if you’re lazy to do a big thinning session, thin every time and vice versa

 

[happy_c]

@ian — When you say that some people thin with every sharpening, I’m assuming they’re doing it with higher-grit stones, not pulling out the 220 grit or belt sander every time?

 

[Mikeltee]

What kind of belt sander are you guys using? What advantage would one gain by using a $500 2x72 vs the $50 Harbor Freight one if they are only breaking it out every once and awhile? Sanding by hand, I would be afraid I'd cut myself and/or really mess up the edge? I feel as if I'd have more control once I got my timing down with a belt sander and it would take a fraction of time.