KitchenCommander
Well-Known Member
Can never have too many threads on blade thinning. I wanted to share my first few thinning projects and post some photos for those who are interested. These are all cheap knives with poor to average geometries so I really got a feel for re-working the geometry of a blade. They came out mostly flat ground on each side after thinning, and I have no idea if I got any asymmetry or not. I could very well have created a slightly left handed grind and not even know it. My guide was the original edge and trying to get the primary grind as close to the bevel as possible. I used a belt sander for the two larger knives as a starter, then used both knives for a bit. Later I came back to finish the job on the stones and to get some more practice. Here is how it went.
Progression"
King 250/1000 grit combo (250 grit)
Gesshin 400 soaker
King 250/1000 combo (1000 grit)
Gesshin 2000 soaker
800 grit wet-dry sandpaper
Project #1 Chicago Cutlery 42S 8" stainless chef knife.
No power tools here. The original grind was pretty decent (see my reviews of both Chicago's in reviews forum). This was originally only thinned near the edge, but I decided to give this a go as my first try on the stones. Before and after choil shots and some pics of the final finish.
Original Chicago Cutlery knives 44S and 42S's. Only the 44 and one 42S is shown. Gave away the other 2.
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original choil
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Finish after full stone progression. Not super even because this is just a travel knife. Only done for practice really. I only use this knife few times a year when going to families houses on the holidays. Cuts great, but doesn't hold an edge very well. Worth the time for experience and a great travel knife.
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Choil shot after completion. Doesn't look all that different than the original, but there was some thinning done. The original grind was average, so I was really only getting a feel for the stones and evening out the grind. Cuts well, but the tip is a bit thick. The edge is reasonably thin for a knife like this. I spent some time near the last 1/4 near the edge to add some convexity. I think it worked a little.
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Project #2 Forgecraft 10" chef knife.
This knife started out on the belt sander.. I went slow and not as thin on this one because I really like this knife and didn't want to overheat it or overgrind the edge. It came out good, and performance was admirable for a power tool thinning job, but the bevel still seemed a little wider than I would like.
Forgecraft now ready for some work on the stones
Orignial Knife
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Belt Sander thinning, refinished with sand paper only, to 1000 grit. Looks pretty nice, but there are some deep scratches from the belt, and the edge is not as thin as I wanted. Sweet patina though.
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Final product after full stone progression and further thinning. Edge much thinner, choil shot shows this. IDK if my sharpening was weird, or I had more convexing on the right side than I thought, but the left bevel is very small, and the right bevel is much larger. This is good from what I believe about asymmetry, so maybe I got lucky. More testing will tell because I haven't cut with it much at all yet. Large streak on the face is not a scratch. You can see clearly the shinogi (?) line where the finish gets dull, this is where the stones made contact. The belt sander went a little higher, but I didn't bother blending the two all that much. Not worth the extra effort.
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Choil shot after completion
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Project #3 Chicago Cutlery 44S 10" stainless chef knife
This also got a thinning on the belt sander. I do not have a choil shot of this first try, but I do have a pic of the finish after the first try. Then many pics of the full progression and finished product.
Original Choil Shot. Thick down to about 1/4" from the edge, then a rough bevel before final sharpening. Not a very good cutter.
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First try with the belt sander, refinished with sand paper, re-handled with Wenge
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Belt sander scratches and finish before thinning with stones
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250 grit cleaning up the uneven sander grind
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250 grit King
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400 grit Gesshin
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1000 grit king
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2000 grit Gesshin. You can see the scratches are less deep and some shine is coming through
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800 grit paper. Its not as even as it looks in the pic.
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800 grit paper showing some left over scratches. Not too worried because this is going in the travel case with the 8" one above. The finish is smooth and should perform great now.
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Choil shot after completion. Quite thin behind the edge now. Choil shot is deceiving because the rounding makes it look concave, but its not. the right side of the choil was over ground as you can slightly see in the photo above. But I assure you it is much thinner than before.
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I hope this is of use to someone. Some notes on my experiences.
Refinishing takes twice as long as actually thinning. thinning is only with one stone. Refinishing is the next 3-4 grits up. The lower you finish at the less time it take.
Stay on each grit longer than you think. The Forgecraft came out the most even because I spent a LOT of time on each grit. The 44S cam out the worst because I got impatient on the 2000 grit and did not get all of the 1K scratches out. This is evident in one of the photos as I wanted to show. The 800 grit sand paper did not cover those scratches like I wanted. Not a big deal here, but on a $150+ knife, I would probably spend the extra time making the finish more even.
Convexity: no comment, I am not experienced enough to create my own convexity on the bevel. I did try to leave some meat at the edge and somewhat convex the last 1/4" of the grind. It seemed to work when I sharpied the edge there was some left unless I lifted the spine a couple degrees. Maybe it worked, maybe it didn't, but I tried.
Spend more time at the tip. The heel seemed to do fine, but I could not get the tip of any of these knives as thin as I wanted. This was probably because they all had zero taper and it is hard to grind in a distal taper, so ymmv on this one.
Stone Hardness: the King was very soft, the Gesshins much harder. I had a more enjoyable experience doing the thinning on the soft stones. They seemed more forgiving and I could get a more even finish than on the harder stones. I did not like flattening them as the Kings dish very quickly. Its a trade off, but if I had a diamond flattening plate (I don't), then I would probably favor softer stones for refinishing and harder stones for sharpening or the first thinning to set a nice even grind. The King 1000 was my most enjoyable step due to the feel and softness of the stone.
Progression: I am satisfied with my progression. For knives with poor initial grinds, a 200-300 grit stone is recommended, the Gesshin 400 cut well, but not fast enough to remove as much metal as I did. For knives with already good geometry, I will probably just start with the Gesshin 400. These 3 knives needed lots of work, and I wanted practice with low grit, so I went all the way. On the fine side, the 2000 grit seemed to pair well with the 800 grit sand paper as long as you get the finish even. The Forgecraft turned out well, the 44s didn't get enough time on the 2K and the finish suffered. Maybe a 3-4K stone would help make the finish a little more even and fine for the 800 grit paper to come behind it an top it off.
Thanks for reading. Please post thoughts comments or questions you may have.
Progression"
King 250/1000 grit combo (250 grit)
Gesshin 400 soaker
King 250/1000 combo (1000 grit)
Gesshin 2000 soaker
800 grit wet-dry sandpaper
Project #1 Chicago Cutlery 42S 8" stainless chef knife.
No power tools here. The original grind was pretty decent (see my reviews of both Chicago's in reviews forum). This was originally only thinned near the edge, but I decided to give this a go as my first try on the stones. Before and after choil shots and some pics of the final finish.
Original Chicago Cutlery knives 44S and 42S's. Only the 44 and one 42S is shown. Gave away the other 2.
original choil
Finish after full stone progression. Not super even because this is just a travel knife. Only done for practice really. I only use this knife few times a year when going to families houses on the holidays. Cuts great, but doesn't hold an edge very well. Worth the time for experience and a great travel knife.
Choil shot after completion. Doesn't look all that different than the original, but there was some thinning done. The original grind was average, so I was really only getting a feel for the stones and evening out the grind. Cuts well, but the tip is a bit thick. The edge is reasonably thin for a knife like this. I spent some time near the last 1/4 near the edge to add some convexity. I think it worked a little.
Project #2 Forgecraft 10" chef knife.
This knife started out on the belt sander.. I went slow and not as thin on this one because I really like this knife and didn't want to overheat it or overgrind the edge. It came out good, and performance was admirable for a power tool thinning job, but the bevel still seemed a little wider than I would like.
Forgecraft now ready for some work on the stones
Orignial Knife
Belt Sander thinning, refinished with sand paper only, to 1000 grit. Looks pretty nice, but there are some deep scratches from the belt, and the edge is not as thin as I wanted. Sweet patina though.
Final product after full stone progression and further thinning. Edge much thinner, choil shot shows this. IDK if my sharpening was weird, or I had more convexing on the right side than I thought, but the left bevel is very small, and the right bevel is much larger. This is good from what I believe about asymmetry, so maybe I got lucky. More testing will tell because I haven't cut with it much at all yet. Large streak on the face is not a scratch. You can see clearly the shinogi (?) line where the finish gets dull, this is where the stones made contact. The belt sander went a little higher, but I didn't bother blending the two all that much. Not worth the extra effort.
Choil shot after completion
Project #3 Chicago Cutlery 44S 10" stainless chef knife
This also got a thinning on the belt sander. I do not have a choil shot of this first try, but I do have a pic of the finish after the first try. Then many pics of the full progression and finished product.
Original Choil Shot. Thick down to about 1/4" from the edge, then a rough bevel before final sharpening. Not a very good cutter.
First try with the belt sander, refinished with sand paper, re-handled with Wenge
Belt sander scratches and finish before thinning with stones
250 grit cleaning up the uneven sander grind
250 grit King
400 grit Gesshin
1000 grit king
2000 grit Gesshin. You can see the scratches are less deep and some shine is coming through
800 grit paper. Its not as even as it looks in the pic.
800 grit paper showing some left over scratches. Not too worried because this is going in the travel case with the 8" one above. The finish is smooth and should perform great now.
Choil shot after completion. Quite thin behind the edge now. Choil shot is deceiving because the rounding makes it look concave, but its not. the right side of the choil was over ground as you can slightly see in the photo above. But I assure you it is much thinner than before.
I hope this is of use to someone. Some notes on my experiences.
Refinishing takes twice as long as actually thinning. thinning is only with one stone. Refinishing is the next 3-4 grits up. The lower you finish at the less time it take.
Stay on each grit longer than you think. The Forgecraft came out the most even because I spent a LOT of time on each grit. The 44S cam out the worst because I got impatient on the 2000 grit and did not get all of the 1K scratches out. This is evident in one of the photos as I wanted to show. The 800 grit sand paper did not cover those scratches like I wanted. Not a big deal here, but on a $150+ knife, I would probably spend the extra time making the finish more even.
Convexity: no comment, I am not experienced enough to create my own convexity on the bevel. I did try to leave some meat at the edge and somewhat convex the last 1/4" of the grind. It seemed to work when I sharpied the edge there was some left unless I lifted the spine a couple degrees. Maybe it worked, maybe it didn't, but I tried.
Spend more time at the tip. The heel seemed to do fine, but I could not get the tip of any of these knives as thin as I wanted. This was probably because they all had zero taper and it is hard to grind in a distal taper, so ymmv on this one.
Stone Hardness: the King was very soft, the Gesshins much harder. I had a more enjoyable experience doing the thinning on the soft stones. They seemed more forgiving and I could get a more even finish than on the harder stones. I did not like flattening them as the Kings dish very quickly. Its a trade off, but if I had a diamond flattening plate (I don't), then I would probably favor softer stones for refinishing and harder stones for sharpening or the first thinning to set a nice even grind. The King 1000 was my most enjoyable step due to the feel and softness of the stone.
Progression: I am satisfied with my progression. For knives with poor initial grinds, a 200-300 grit stone is recommended, the Gesshin 400 cut well, but not fast enough to remove as much metal as I did. For knives with already good geometry, I will probably just start with the Gesshin 400. These 3 knives needed lots of work, and I wanted practice with low grit, so I went all the way. On the fine side, the 2000 grit seemed to pair well with the 800 grit sand paper as long as you get the finish even. The Forgecraft turned out well, the 44s didn't get enough time on the 2K and the finish suffered. Maybe a 3-4K stone would help make the finish a little more even and fine for the 800 grit paper to come behind it an top it off.
Thanks for reading. Please post thoughts comments or questions you may have.
Great job though, I bet they cut so much better now.
