Thinning...?

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Here's one that's ground this way deliberately exaggerated my me on a very thick spined knife.

Here's the convex sideView attachment 126425

And here's the relief bevel side. You can see the difference


View attachment 126426

On some knives the relief side is even concave.
I talked about that here




That's one funky looking apple man, I've never seen one of those before. I've been eating these awesome pears from Korea lately, they have a really delicate flavor and sweetness. They kind of taste a little like caramel, with the slight essence of cantaloupe floating around, they're really tasty and have a nice texture. Anyway, how do you get convexity using a stone? I'm thinking a strop would be handy to add some convexity, but I haven't really tried it, I'm just working off of theory.

P.S.,

I like your Sujihiki, that's the next type of knife I plan on buying, though I'm not in a rush or anything.
 
That's one funky looking apple man, I've never seen one of those before. I've been eating these awesome pears from Korea lately, they have a really delicate flavor and sweetness. They kind of taste a little like caramel, with the slight essence of cantaloupe floating around, they're really tasty and have a nice texture. Anyway, how do you get convexity using a stone? I'm thinking a strop would be handy to add some convexity, but I haven't really tried it, I'm just working off of theory.

P.S.,

I like your Sujihiki, that's the next type of knife I plan on buying, though I'm not in a rush or anything.

Those red fleshed apples taste similar to a Fuji or gala but the red flesh doesn't oxidize or something. I forget the point exactly and I've only seen them once or twice.


But the key to getting convexity with a stone is finger pressure. There will be a natural convexing that occurs when you switch directions back and forth. You can focus that convexing with your finger pressure on the blade. Starting with the knife very flat on the stone working at first with your pressure focused on the middle of the face of the knife and then gradually shifting that pressure down to the edge. Then you add a micro bevel at the end which has the affect of accelerating the convexity toward the apex.
 
the Harbor Freight runs at 3450rpm which puts its speed way to high for most anything except hogging of steel for reprofiling. I know people do sharpen on these, but for fine knives i would not recommend it. the high speed can generate major heat and potentially ruin your blade.

Truth. I have burnt so many edges on mine. It's basically impossible for me to do any work near a thin tip without burning it.
 
I'm thinking a strop would be handy to add some convexity, but I haven't really tried it, I'm just working off of theory.

A strop will never remove enough metal to significantly affect the geometry. Sandpaper on a soft backing works, but you can also do it on stones like stringer says.
 
I have a Herder leather strop glued on hard wood. Rough side treated with 20 micron diamond powder. Yes, it does contribute to smooth convexity.
Screenshot_20210510_012200_com.android.chrome.jpg
 
The Manticore is a beast.

Be aware, you may need to dress the surface to get it working right. Mine was so compacted it seemed almost slick. Some heavy scratching (read grinding down) of some screws and then re-profiling a thick Buck knife got it performing well.
Did yours take a long time to ship? I ordered mine on the 4th and it still has not shipped. It seems a bit odd that you pay for priority mail and then wait so long for it to get into the mail.
 
A strop will never remove enough metal to significantly affect the geometry. Sandpaper on a soft backing works, but you can also do it on stones like stringer says.

Hmmmmm. Here's an interesting article with SEM images of stropping without compounds
https://scienceofsharp.com/2014/08/13/what-does-stropping-do/
And with compounds.
https://scienceofsharp.com/2015/02/09/the-pasted-strop-part-1/https://scienceofsharp.com/2015/02/22/the-pasted-strop-part-2/https://scienceofsharp.com/2015/03/31/the-pasted-strop-part-3/https://scienceofsharp.com/2016/05/29/the-pasted-strop-part-4/
 

Sure, you can create a little bit of convexity near the edge, but I think the question was about creating a convex blade face. You can probably do that on a strop too, but it may take you a few years.

I always love those images, though. 🤩🤩🤩
 
Sure, you can create a little bit of convexity near the edge, but I think the question was about creating a convex blade face. You can probably do that on a strop too, but it may take you a few years.

I always love those images, though. 🤩🤩🤩
Ohhh. My bad. Didn't read enough of the thread. That said, if you did try to convex a blade with a strop and it took years, you would be a master of epic proportions able to teach said skill and become a millionaire.
 
  • Haha
Reactions: ian
Did yours take a long time to ship? I ordered mine on the 4th and it still has not shipped. It seems a bit odd that you pay for priority mail and then wait so long for it to get into the mail.

No but I've had mine for a long time. I don't keep up anymore but last I looked, Benjamin (owner) said they were slammed. He's a good guy so if you have any questions or concerns, I'd just try to contact him.
 
Truth. I have burnt so many edges on mine. It's basically impossible for me to do any work near a thin tip without burning it.
yeah pretty much impossible on fine belts. only advice I can give is water or ice bath dip first and start at the tip rather than at the heel. it'll give you a fighting chance.
 
Alright, a new thinning question...

When you're doing more extensive thinning and for performance not polishing, after a good bit of work do you check performance before moving up in stones?

I guess maybe more for those times when you suspect there will be multiple sessions. Do you polish up the sides some and then after a few uses realize you want to take more off and start all over? I don't mean the full monty but fix it up a fair bit. Do you just leave it rough and use for a bit and get it dialed in before any of that? To some extent, the blade finish can have at least some influence on the performance.
 
Alright, a new thinning question...

When you're doing more extensive thinning and for performance not polishing, after a good bit of work do you check performance before moving up in stones?

I guess maybe more for those times when you suspect there will be multiple sessions. Do you polish up the sides some and then after a few uses realize you want to take more off and start all over? I don't mean the full monty but fix it up a fair bit. Do you just leave it rough and use for a bit and get it dialed in before any of that? To some extent, the blade finish can have at least some influence on the performance.
I'll use a higher grit stone, 2k+ or sandpaper 1k+ really quick. Just enough to get rid of the grabbiness. Then cut stuff for awhile to check the progress.
 
I'll use a higher grit stone, 2k+ or sandpaper 1k+ really quick. Just enough to get rid of the grabbiness. Then cut stuff for awhile to check the progress.
Within the last month or so, I kind of learned to do this the hard way. I use my sg120 to set geo and it leaves super grabby bevels. Just started to hit it with sg1k real quick and it makes such a difference
 
Alright, a new thinning question...

When you're doing more extensive thinning and for performance not polishing, after a good bit of work do you check performance before moving up in stones?

I guess maybe more for those times when you suspect there will be multiple sessions. Do you polish up the sides some and then after a few uses realize you want to take more off and start all over? I don't mean the full monty but fix it up a fair bit. Do you just leave it rough and use for a bit and get it dialed in before any of that? To some extent, the blade finish can have at least some influence on the performance.
A little bit of brushing with 800grit sandpaper leaves a good enough finish for testing to eliminate excess stiction or drag
 
@Rangen

Yep I've done it lol. Burrs can get pretty huge actually, foil-ey messes and chunks. Coarser stone and more time spent without properly removing the burr leads to larger nastier burrs
 
Turns out if you thin past the edge bevel at any point, you can get little chunks of steel, pieces of ejected burr, on your stone that put scratches into your nice curated finish.

Do NOT ask me how I know this.
Yep, I’ve learned the hard way to cut on a relief bevel and deburr often when polishing.
@Rangen

Yep I've done it lol. Burrs can get pretty huge actually, foil-ey messes and chunks. Coarser stone and more time spent without properly removing the burr leads to larger nastier burrs
Can happen with very fine stones and very small burrs too
 
Yep I've done it lol.
Someday, I too will be able to laugh about it. This is not that day.
Yep, I’ve learned the hard way to cut on a relief bevel and deburr often when polishing.

Can happen with very fine stones and very small burrs too
Yeah, I guess that seems obvious, in retrospect. I don't remember it in the "Polishing 101" threads, but of course one can't really pay proper attention until actually doing the thing.
 
Someday, I too will be able to laugh about it. This is not that day.

Yeah, I guess that seems obvious, in retrospect. I don't remember it in the "Polishing 101" threads, but of course one can't really pay proper attention until actually doing the thing.
Wasn’t obvious to me at first. Only pain and suffering taught me this lesson
 
I'll use a higher grit stone, 2k+ or sandpaper 1k+ really quick. Just enough to get rid of the grabbiness. Then cut stuff for awhile to check the progress.
Remember the slightest remaining burr can influence the idea you get from a geometry. If you experience an unexpected steering for sure it's a burr. The need of a full sharpening after thinning is a good reason to prefer larger thinning operations over a lot of small steps, apart from the need to make the looks more or less acceptable — not my first concern. By the way, I prefer to give the blade and myself a day of rest after heavy thinning before sharpening. Indeed, performing a rapid sharpening at 2k or so may give an impression of the effects of the thinning, but again, careful deburring can't be skipped. And later on, it will require a full progression. It is an illusion to thin without performing a new sharpening.
 
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