Advise on fixing the edge

I am new to freehand sharpening, waiting now for my newly ordered stones to arrive. Have a couple of knives pictured below that had been sort of screwed up by 'professional' sharpeners. I need the edge to be in a straight line starting at the bolster all the way to where the curve to tip starts so that there is no gap between the edge and the cutting board.

What is the right approach and technique to do this with whetstones?

Any advise shall be appreciated.

Couple more pictures to illustrate the gap. I know that most of the gap is because of the bolster and I can file some away, but the edge itself is not straight too.

Those knives look robust enough for outdoor work. The only thing you can do here is to grind away the return (bottom of the bolster) and perhaps the middle of the blade until you get the heel to lie flat. You might want to do this on a piece of concrete pavement rather than gouge your whetstone. Alternatively, you can get a new kitchen knife (possibly Japanese) without a bolster and a straighter profile and use the bolstered knives for other things, like butchering sheep.

I've already ordered Tojiro DP Gyuto as a starter knife and am planning to use these to learn sharpening. Will removing metal from bolster area and middle (the bolster itself is a very soft alloy, I shall remove it with a file) consume too much of stone? I am going to have a DMT 8in continuous diamond plate (coarse) and a combination 1000/6000 stone by King.

I believe both of your pchak knives were made using relatively soft steel, so there shouldn't be troubles in grinding them with sandpaper or DMT. The only reason why you might not want to use waterstones for grinding is time. Cheap silicon carbide stones, sandpaper or diamond plates would do work much faster. Personally I wouldn't touch bolster/finger guard… it might complicate grinding/sharpening, but would preserve authenticity of knives.

icanhaschzbrgr said:

I believe both of your pchak knives were made using relatively soft steel, so there shouldn't be troubles in grinding them with sandpaper or DMT. The only reason why you might not want to use waterstones for grinding is time. Cheap silicon carbide stones, sandpaper or diamond plates would do work much faster. Personally I wouldn't touch bolster/finger guard… it might complicate grinding/sharpening, but would preserve authenticity of knives.

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Another option is to bring these to a sharpener and have him touch the flat sidewall of his rotating stones with the edge to render it straight, and then use DMT to put a new edge. Would this work?

x737 said:

Another option is to bring these to a sharpener and have him touch the flat sidewall of his rotating stones with the edge to render it straight, and then use DMT to put a new edge. Would this work?

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Of course a good sharpener could easily bring those knives into good working condition. Yet a bad sharpener could make things worse.
If I were you, I'd try to fix knives myself to get experience in freehand sharpening and fixing profiles.

Thanks icanhaschzbrgr, that makes sense. Will report back in a couple weeks when my merchandise arrives from across the pond(s)

What you should try is having the fingerguard flush with the relief bevel. I use automotive sandpaper on linen, P120, first at 80 degree to have the edge touch the board over its entire length, than thinning a lot, and finally putting an edge on it.

Benuser, what do you put under the sandpaper, just any hard surface or something special?

I guess short strokes on the longer side of DMT shall be too costly (killing the plate early)?

Do you have access to a belt sander? As long as you watch the temperature of the blade, it's a pretty quick solution for dealing with the bolster and straightening the edge before putting an edge on.

Mrmnms said:

Do you have access to a belt sander? As long as you watch the temperature of the blade, it's a pretty quick solution for dealing with the bolster and straightening the edge before putting an edge on.

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I don't unfortunately

x737 said:

Benuser, what do you put under the sandpaper, just any hard surface or something special?

I guess short strokes on the longer side of DMT shall be too costly (killing the plate early)?

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Just a piece of wood, hard rubber works as well, it will convex a bit more, hard stuff is more precise, soft stuff is faster. No own experience with DMT plates, from what I understand they cause very deep grooves,

I wouldn't sacrafice my stones. Benuser's method is good option. It's an inexpensive way to straighten the edge and remove the bolster before going to stones. I've used the side of coarse stones to get a straight edge on a messed up knife.

Mrmnms said:

I wouldn't sacrafice my stones. Benuser's method is good option. It's an inexpensive way to straighten the edge and remove the bolster before going to stones. I've used the side of coarse stones to get a straight edge on a messed up knife.

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Oh that's a nice idea too, although I wouldn't have a coarse stone. Could also use the length of a coarse file.

Yes, but I would likely go the sandpaper route.

x737 said:

Oh that's a nice idea too, although I wouldn't have a coarse stone. Could also use the length of a coarse file.

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Most files are just too soft,

A half way decent knife is going to be as hard as the file, including the bolster. If not, the knife is hardly worth the effort to sharpen, although you could learn about angles, etc. on it.

Coarse sandpaper on a flat surface will work better than a file.

And this is exactly the reason I dislike heavy bolsters that extend to the edge -- it is nearly impossible to get the last half inch of the blade decently sharp without a huge amount of effort.

Peter

Googling around, I found out there shall be another issue. Once the edge is straight, the formerly recessed parts will be almost sharp, while the ground away parts are going to be fairly thick. And when I start thinning/sharpening normal way on the stones, there are high chances that regrinds shall form again. The way to address this is to use the length of the stone for thinning, but in my case bolster will interfere again. Thinking of grinding the bolster away altogether.

I think you could grind the bolster away at a 45 degree angle and then work on the edge of the blade. Neither blade appears to be in too bad condition, so the advice given is all solid. I agree that you can make these into decent looking blades and in the process learn quite a bit about sharpening/profiling/thinning. You said that you've ordered stones, what did you order? Did you also order a flattening stone/plate?

x737 said:

Googling around, I found out there shall be another issue. Once the edge is straight, the formerly recessed parts will be almost sharp, while the ground away parts are going to be fairly thick. And when I start thinning/sharpening normal way on the stones, there are high chances that regrinds shall form again. The way to address this is to use the length of the stone for thinning, but in my case bolster will interfere again. Thinking of grinding the bolster away altogether.

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There's no need for that if you do what Benuser suggested earlier in the thread.Grinding the finger guard away is a real PITA.

chinacats said:

I think you could grind the bolster away at a 45 degree angle and then work on the edge of the blade. Neither blade appears to be in too bad condition, so the advice given is all solid. I agree that you can make these into decent looking blades and in the process learn quite a bit about sharpening/profiling/thinning. You said that you've ordered stones, what did you order? Did you also order a flattening stone/plate?

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As I said I am going to have continuous diamond DMT (coarse) to double as a lapping plate. Plus a 1000/6000 combination King stone.

Alright, I finally received my sharpening gear yesterday and played with the knives.

Here is the result:



No sandpaper was used. I speculated that simply grinding on DMT putting the knife diagonally and waiting for burr to appear all along the edge should do the magic because the hollow part will not start grinding away until it is in a straight line with the neighbouring areas. And it worked! Now the profile is straight. But I am disappointed with the quality of the edge. It is not nearly as sharp as my starter Tojiro DP. It doesn't cut paper, but rather saws it. Still, the knife is sharper than it has ever been. Probably I did something wrong. The metal btw was indeed very soft and coarse DMT would eat through quite quickly.

Make sure to get the deep grooves from the DMT away with different grades of sandpaper, or a good coarse stone, before even dream about setting a bevel. Otherwise the grooves will make your final edge very weak.

Benuser, I had lots of 1000 and 6000 grit polishing afterwards

My sharpening ability increased dramatically when I got a 20x magnifier. One I could SEE what I was doing, I learned to quit rolling the blade. Worst habit I have is removing the apex while de-burring -- I get rid of the burr just fine, but also remove the edge! Dull knife with a lovely polished edge.

I'm guessing you have not achieved a real apex yet. Go back to the 1000 grit stone and work carefully to draw a fine burr again, then very gently de-burr by stropping on the stone. One high angle wipe will remove the edge completely, as I've discovered, and you won't recover it on the 6000 grit stone in less than a week or so, the 6K doesn't remove enough material fast enough to re-establish the edge.

If the knife is fairly soft, you won't be able to keep that polished edge anyway, but if you get it even for just a couple cuts, you know you can sharpen anything.

When you get a good edge on the Tojiro, it will cut a cherry tomato in half if you drop it onto the upturned edge from 8" or so.....

Peter

x737 said:

Benuser, I had lots of 1000 and 6000 grit polishing afterwards

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You should start with an abrasive almost as coarse as the one that caused the grooves/scratches, and from that one on, refine little by little.

Benuser said:

You should start with an abrasive almost as coarse as the one that caused the grooves/scratches, and from that one on, refine little by little.

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For an amateur, I believe anything on top of DMT+1000+6000 would be an overkill. Will keep working on my skills with what I have. BTW, the knives lose their height at a scaring pace.

x737 said:

For an amateur, I believe anything on top of DMT+1000+6000 would be an overkill. Will keep working on my skills with what I have. BTW, the knives lose their height at a scaring pace.

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I think what Keith means is that it is easier to start at a grit that matches the depth of the initial scratches. Saves you some time at each step and makes for a smoother finish in the end...probably some 200 grit then 400 then 800 and so on...sandpaper is cheap so easy to have some in each grit...
BTW, good job so far. They may only get so sharp, but the skills you have acquired will transfer easily as you try this on other knives.
Cheers

I looked at your picture again, and I suspect some major thinning is in order. If you look closely, you can see where the blade was ground to produce the taper above the edge, and now that you have re-shaped the "belly" the blade just behind or above the edge is quite fat in the middle. No matter how sharp the actual edge is, that fat blade is going to wedge and make the knife act as though it's dull.

Might not have been all that thin to start with, either.

Peter