Edge repair

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childermass

childermass

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Hello fellow sharpeners!

I think I need some help:
Maybe this is a minor thing and I‘m thinking too much about it but anyway...

A friend of mine tried to sharpen his Shirogami II Gyuto with a crappy pull-through sharpener although I told him not to do these kind of things.
I suppose he used a lot of force like you sometimes have to with very soft stainless steel knives.
Now the edge is completely full of chipping in various sizes.

This shows a small portion of the blade (I hope I managed to photograph this),
IMG_1289.jpg


but the whole edge looks like this.
IMG_1290.jpg

(please ignore the overall look of the knife, it’s unfortunately not too well cared for but used a lot)

I never had to do such repairs and would be grateful for any hint and tip how I can approach this without ruining the geometry.
My main problem is how do I start?

I got lots of stones to choose from both natural and synthetic. Maybe being a collector pays off now [emoji12]
On the coarse end, which is what I’m most concerned about in this case, I got an AI220 from Watanabe and a Beston 500.

Thanks in advance!
 
I would start with the 220, most likely will need a bit of thinning after the chips are out.
 
BtW, having a fun time with your old Maru, thanks.
That blade doesn't look that bad at all. I'm guessing a good thinning is in order and that is where I would start. By the time you work your way up grit wise and setting the edge along the way, most of the flea bites will be gone. I wouldn't bother trying to get rid of all of them. they'll work their way out by the 2nd or third full sharpening.
Haven't worked with an AI220, but the B-500 should do a lot to get things sorted out without much issue.
Have fun.
 
Another vote for starting with the 220, thinning the edge first and then cutting a new bevel. That should take care of the chips, which don't appear to be that bad, at least in the pics. Then use the 500 to remove the scratches from the 220. You could just start with the 500, as suggested in another post, but you may find it to be too slow.
 
As an update: After I finally got to do it after postponing it for almost a month it turned out pretty well. The knife is razor sharp again. Ok, it‘s not looking as nice as when it was new, but my friend will be mean to it anyway so who cares [emoji23].
Unfortunately I somehow erased the pictures from my phone so I can’t show you the result.
 
So I had to something similar recently with a friends knife that was in far worse shape. First time I had actually done anything like this. Essentially I established a new primary bevel by thinning the you know what out of it. I took my time with the thinning as it seemed the most likely place to screw it up. I continued thinning both sides as evenly as possible until a new bevel was established and a small bead formed on what was the new edge (Stop as soon as you feel even the smallest bead). I then deburred the new edge and then created what I suppose would be mini bevel, that was a roughly 14' edge angle. Once I finished all of that I went back and wet sanded the knife with a simple progression of Rhynowet to remove all the scratches I created from thinning, which left a nice Kasumi finish.

The geometry of the knife is changed there is now a definitive primary bevel where there wasn't one before, but it looks really clean and is hair popping sharp. Probably the sharpest edge I've ever been able to create. So far the feedback is outstanding. The knife is really sharp and the new edge is very durable.

FYI the progression I used was: (thinning) Atoma 140 > Gesshin 400 (Setting new edge) AI#1k > Gesshin #2k > Aizu
 
childermass said:
As an update: After I finally got to do it after postponing it for almost a month it turned out pretty well. The knife is razor sharp again. Ok, it‘s not looking as nice as when it was new, but my friend will be mean to it anyway so who cares [emoji23].
Unfortunately I somehow erased the pictures from my phone so I can’t show you the result.
Click to expand...

Awesome news!
 
Hanmak17 said:
So I had to something similar recently with a friends knife that was in far worse shape. First time I had actually done anything like this. Essentially I established a new primary bevel by thinning the you know what out of it. I took my time with the thinning as it seemed the most likely place to screw it up. I continued thinning both sides as evenly as possible until a new bevel was established and a small bead formed on what was the new edge (Stop as soon as you feel even the smallest bead). I then deburred the new edge and then created what I suppose would be mini bevel, that was a roughly 14' edge angle. Once I finished all of that I went back and wet sanded the knife with a simple progression of Rhynowet to remove all the scratches I created from thinning, which left a nice Kasumi finish.

The geometry of the knife is changed there is now a definitive primary bevel where there wasn't one before, but it looks really clean and is hair popping sharp. Probably the sharpest edge I've ever been able to create. So far the feedback is outstanding. The knife is really sharp and the new edge is very durable.

FYI the progression I used was: (thinning) Atoma 140 > Gesshin 400 (Setting new edge) AI#1k > Gesshin #2k > Aizu
Click to expand...

Great stuff! What was the sandpaper progression you used?
 
400>800>1200>2k>2.5k

In retrospect I wish I had lower grit to start with. The Atoma is a very blunt instrument that leaves deep gashes in the steel.

One bit of advice that Nutmeg gave me which really helped was to begin the sanding perpendicular to the edge (vertical) and progress to paralell as I ran through the progression. This made it easy to spot leftover grind marks that would have otherwise been missed if I just sanded paralell as I had always reead.

The knife was a beater so I didn't spend as much time as I otherwise would have but as an initial experiment it was a good learning experience.

Learned more about sharpening doing this then I would have otherwise, highly recommend this to anyone interested in learning to sharpen, it gives you a very clear perspective on blade, bevel and edge geometry.
 
Hanmak17 said:
Learned more about sharpening doing this then I would have otherwise, highly recommend this to anyone interested in learning to sharpen, it gives you a very clear perspective on blade, bevel and edge geometry.
Click to expand...

True, I learned a lot too. Made some mistakes of course, but other than I built the handle of this knife myself it’s nothing special so no real harm done. It came out a little asymmetrical but it did not harm the performance of the knife. I think it might be worth doing some more repairs on damaged knives [emoji848].
 
Just one remark: from the profile picture I got the impression that the heel area is slightly protruding. Check for an even board contact. Often that section is a bit thicker and needs longer sharpening.
 
Benuser said:
Just one remark: from the profile picture I got the impression that the heel area is slightly protruding. Check for an even board contact. Often that section is a bit thicker and needs longer sharpening.
Click to expand...

Yes, that was something I encountered during thinning. This was a problem that was there from the beginning. Fortunately I was able to fix this during the repair.
 
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