When to Thin and Where to Begin?

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Chamber

Chamber

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Couple questions regarding thinning kitchen knives. How do you know when it is time to thin? Also is there any basic information out there for beginners? I have sharpened many knives and razors but never thinned one. Mainly interested in how you hold the knife. Do you lay it flat on the stone or raise a slight angle just enough to take off the shoulders? I have 300 and 500 grit stones are they ideal for thinning?
 
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check out the thinning videos on japaneseknifeimports. If your knife isn't cutting the way you like, or its getting thick behind the edge, thin it. Lots of people recommend thinning with every sharpening session to maintain proper geometry.
 
slickmamba said:
check out the thinning videos on japaneseknifeimports. If your knife isn't cutting the way you like, or its getting thick behind the edge, thin it. Lots of people recommend thinning with every sharpening session to maintain proper geometry.
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Do you have a link to the video? I checked their website and YouTube page and didn’t see anything about thinning.
 
Chamber said:
Do you lay it flat on the stone or raise a slight angle just enough to take off the shoulders? I have 300 and 500 grit stones are they ideal for thinning?
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As for the angle, yes, that sounds about right (depending on the knife you may want a more precise answer). I’ve heard people saying 3-5 degree angles, and that sounds about right for removing shoulders. 300 or 500 should work fine.
 
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Tristan said:
Going to take an unpopular stand, think too many people in this forum thin their knives way too much.
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If you wait too long, restoring the original geometry becomes almost impossible without powered tools.
sharpen4-1.jpg
 
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its a matter of opinion, first answer is pretty accurate. When i don't like how a knife cuts certain ingredients, i start thinning.

My take on thinning
Thinning -
  • step 1: Take a minute to admire the nice finish on your knife. Say goodbye to it
  • step 2: Lay you knife flat on your roughest stone, put pressure on your middle and index finger the places you want to remove metal.
  • Step 3: Grind away
  • step 3.1: Optional, start the pressure directly behind the edge, and continue up the knife for further thinning with convexing.
  • step 4: Take a finer stone or a progression thereof and start removing scratches and eventual an burr if you thinned that deeply.
  • step 4.1: Optional, Repeat step 3.1 for convex knives, dont just focus on the section directly behind the edge, or you might accidentally loose some of your progress/thinness. The first ~20 mm means alot for the overall performance.
  • step 4.2: Optional, go all in for the deburr, high grit stones, loadet leatherstrops or whatever you got
  • Step 5: Take out your finishing stone, put a quick edge on your knife again, your knife will sharpen up much faster now its thinner behind the edge.
  • Step 6: Cut some test ingredients such as: carrots, onions, potatoes. Carrots and onions - Does the knife cut through effortlessly enough? if yes you have thinned far enough. Potatoes - if it sticks, you might have polished the blade road too much, try taking it down to an up to 1000 grit finish, if soft potatoes wedges you have not thinned far enough.
  • Step 7: Judge your process, if you are unhappy go back to step 1. You get the best impression of the knife, if you use it for some meal preps before drawing a conclusion.
  • If you have thinned all the way to the edge, you can tell by the large burr you pull up and as you will hardly be able to see the edge when sharpened, and its still not cutting how you want. Focus on removing steel further up the knife for next thinning, and vice versa.
My take on soft stamped knives - Compound edges (sharpen at a low a angle your comfortable with 10 degrees or something, and maintain the edge as normal)
 
When thining not a wide bevel - one should always assume that the original geometry will be slightly modified.
The end result is usually better since you will normally thin when the performance is not adecuate for you.

When done thinning use progression of wet-dry sandpaper to restore the finish.
 
I generally thin a knife once to get it where I want it behind the edge. I focus on the tip half of the knife. The third of the knife closest to the heel I thicken to increase durability for cutting through bones or popping air vents in cans. Then I thin a little every time I sharpen to maintain the geometry. Home knives get sharpened about twice per year and may never need serious thinning again. Work knives get sharpened one or twice per week and often have micro chips and damage that has to get ground out. So they will occasionally need to be thinned more aggressively than just a few maintenance strokes, especially the tip.

Here's a thread where I show my initial thinning process on a Shi.Han 240 gyuto.

https://www.kitchenknifeforums.com/threads/durability-testing-shi-han-aka-ginrei-240-gyuto.42530/
 
stringer said:
I generally thin a knife once to get it where I want it behind the edge. I focus on the tip half of the knife. The third of the knife closest to the heel I thicken to increase durability for cutting through bones or popping air vents in cans. Then I thin a little every time I sharpen to maintain the geometry. Home knives get sharpened about twice per year and may never need serious thinning again. Work knives get sharpened one or twice per week and often have micro chips and damage that has to get ground out. So they will occasionally need to be thinned more aggressively than just a few maintenance strokes, especially the tip.

Here's a thread where I show my initial thinning process on a Shi.Han 240 gyuto.

https://www.kitchenknifeforums.com/threads/durability-testing-shi-han-aka-ginrei-240-gyuto.42530/
Click to expand...
I just read this and it was totally awesome. I’ve been eyeing shihan knives and it’s good to get a large report on the steel and initial grind. Great read
 
stringer said:
I generally thin a knife once to get it where I want it behind the edge. I focus on the tip half of the knife. The third of the knife closest to the heel I thicken to increase durability for cutting through bones or popping air vents in cans. Then I thin a little every time I sharpen to maintain the geometry. Home knives get sharpened about twice per year and may never need serious thinning again. Work knives get sharpened one or twice per week and often have micro chips and damage that has to get ground out. So they will occasionally need to be thinned more aggressively than just a few maintenance strokes, especially the tip.

Here's a thread where I show my initial thinning process on a Shi.Han 240 gyuto.

https://www.kitchenknifeforums.com/threads/durability-testing-shi-han-aka-ginrei-240-gyuto.42530/
Click to expand...
crlums said:
Lots of good advice here. When I was first starting I fount this resource to be the most thorough and helpful. Its a collaboration between John Broida and Peter Nowlan. Both the video and article are excellent.

https://www.knifeplanet.net/lesson-3-knife-thinning/
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Both of these posts were extremely helpful thank you.
 
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