Tips for getting "shaving sharp"?

L

Leon Husock

Joined
Jul 17, 2019
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285
I can get my knives plenty sharp for cutting vegetables etc, but I never seem to be able to get them sharp enough to shave hair. I can't tell whether this is an issue with my sharpness or whether I just don't know how to shave arm hair with a knife, heh. My process after forging/grinding/finishing the knife is:

Set the micro-bevel with a 220 grit belt and sharpen till I get a burr, then move to an A16 trizact (roughly 1200 grit I think), then A6 trizact (2500 grit I think), then a leather belt with green chrome on it, and then a 4000 grit water stone if it doesn't feel sharp enough after the green chrome. Am I missing something?
 
You're rounding the apex over. Try just the 220 grit and the leather.

If that doesn't work then it means your microbevel is too steep, do a regular bevel.

Personally I only sharpen by hand on stones.

Also 4k is too fine of a grit to crisp an apex, that grit is for refining a sharp apex not creating one. It just doesn't have the abrasive firepower to really crisp a rounded over edge. You would be better off jumping down to ~1000grit, than 4k if you want to polish.


Leon Husock said:
I can get my knives plenty sharp for cutting vegetables etc, but I never seem to be able to get them sharp enough to shave hair. I can't tell whether this is an issue with my sharpness or whether I just don't know how to shave arm hair with a knife, heh. My process after forging/grinding/finishing the knife is:

Set the micro-bevel with a 220 grit belt and sharpen till I get a burr, then move to an A16 trizact (roughly 1200 grit I think), then A6 trizact (2500 grit I think), then a leather belt with green chrome on it, and then a 4000 grit water stone if it doesn't feel sharp enough after the green chrome. Am I missing something?
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cut a piece of paper, where it drags that is an area the is not sharp.

Do the finger nail test and where it slips is not sharp.

Use a magnifing glass under a light, you can see the areas that are not sharp.

I use a 220 belt to get to an apex, then to the stones 220, 400. It has some teeth for bite and cuts hair easily.

To high of a polished edge is good for push cutting, but not cutting hair.

I like my edge to have some teeth to it
 
Lots of good advice above.
I do best when I take the main bevel to quite thin, then do the final edge by hand.
Even then I have sometimes chased it around switching grits back and forth.
I figured it out after I got a wicked edge system that holds the angle better than I can by hand. It never fails. I can do it better now by hand also since I know to really focus on a precisely held angle.
Speaking of which, if you are doing a lot, you might look up some posts from Nathan the machinist about his parallelogram rig...
 
Adam is right - too polished an edge will push the hair aside. A bit of a tooth and it will grab and cut the hair.

Stones are just about essential for very sharp edges. Up to 800/1000 grit is more than enough. Higher than that is for dedicated sashimi and microtome blades.
If using only belts, then do it at 220 grit and just clean it up with a couple passes on a leather strop. A proper leather strop should be mounted to a board so it does not flex. Slapping a sharp edge up and down a loose leather strop ( like the barber's in movies and TV) will make a rounded edge.
 
Usually I kind of set the edge with 120-220. Then go by hand to 320-600-(1200) and then buff/deburr at a 10" rock hard felt wheel loaded with green compound. That gets insanely sharp. The felt wheel has really uped my sharpening results. I have it on a motor hooked to my VFD.
 
My edges will always cut hair, but I find that cutting phone book pages gives me more feedback on the condition of the edge. As stated above, I can easily feel where the knife drags in the slice. That area needs attention. My minimum standards for sharpness is clean PUSH cut on phone book paper for kitchen knives and a clean draw cut for everything else. ( And depending on the purpose, some of those will push cut as well. I almost feel guilty about how little time I spend sharpening. I use my grinder at a VERY slow speed. 120 ceramic to set the edge, followed by an a30 norax, then leather strop with green compound.
 
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I have never used a powered sander to sharpen. My experience is that the toothy edge at about 1000 grit on a stone is a very useful edge. It will shave hair, though not well enough to shave your face. In order to get to that level with a polished edge you have to go much further into the 10k+ range with a good strop.

The polished edge can take you farther into the clean edge needed for shaving, but you have to work for it. Then, in use it becomes an imperfect edge pretty easily.

So it is possible to make a shaving sharp edge at almost any grit. The higher grits just take a little longer to achieve with little added benefit, if any.
 
Kevin McGovern said:
My edges will always cut hair, but I find that cutting phone pool pages gives me more feedback of the condition of the edge. As stated above, I can easily feel where the knife drags in the slice. That area needs attention. My minimum standards for sharpness is clean PUSH cut on phone book paper for kitchen knives and a clean draw cut for everything else. ( And depending on the purpose, some of those will push cut as well. I almost feel guilty about how little time I spend sharpening. I use my grinder at a VERY slow speed. 120 ceramic to set the edge, followed my a 30 norax, then leather strop with green compound.
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Yes the PUSH cut
 
I so appreciate this site. I had 14 student who made knives this year at school but they needed to be sharpened. With this covid shut down we are behind and I wasn't going to be able to let them use stones to put the first edge on their knives. After reading this thread I got out my bubble jig and set a 20 degree angle on it. Got my grinder running slow with a 120 grit belt. After a few knives I could put my secondary bevel ( I think its called that) on and have a burr with about 4 passes on each side with a bit of pressure on the blade. I put on a 220 grit and did 2 passes on each side. Ran them across a strop and they cut paper nicely. Had 2 that would catch on the paper so I did a few strokes on a stone and across the strop again and they cut clean. This took me 1.5 hrs.
I have learned so much on this website and there is so much information and people who help out here. Thanks so much.
 
Razors have a different geometry than most knives, and are sharpened differently.
 
I can usually pop hair pretty easily after sharpening with 220 to 320, and then knocking the wire off on my buffer (usually just a couple of passes per side). You have to made sure you're actually raising a wire/burr along the whole edge before you take it to the buffer though.
 
Try practicing on a course to medium stone. I can get a blade to easily cut hair with a DMT course stone. If you want to polish after that go for it but you will be able to dial things in easier with the low grit stones and the teeth really do cut better. Also instead of a leather strop try just using soft wood like a paint stir stick. Leather can have enough give that if you use to much pressure it will still round over your edge. You will be surprised about what you can do in the 300-600 grit range. From what I understand you get better edge retention as well as a bonus. You might want to just stop there or at least you will have a foundation to start from so you can limit variables as you polish your edge. A sharp 220 grit belt running on low speed and sprayed with soapy water will take you from dull to shaving sharp in 30 seconds. I almost never take more than 2 minutes to sharpen any knife even when by hand any more.
 
Storm W said:
Try practicing on a course to medium stone. I can get a blade to easily cut hair with a DMT course stone. If you want to polish after that go for it but you will be able to dial things in easier with the low grit stones and the teeth really do cut better. Also instead of a leather strop try just using soft wood like a paint stir stick. Leather can have enough give that if you use to much pressure it will still round over your edge. You will be surprised about what you can do in the 300-600 grit range. From what I understand you get better edge retention as well as a bonus. You might want to just stop there or at least you will have a foundation to start from so you can limit variables as you polish your edge. A sharp 220 grit belt running on low speed and sprayed with soapy water will take you from dull to shaving sharp in 30 seconds. I almost never take more than 2 minutes to sharpen any knife even when by hand any more.
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I was impressed with how quickly it all went considering these knives didn't have their secondary bevels on them yet. And I was really excited by how sharp they were with so little effort. This has completely changed my knife sharpening routines.

I have seen a few people mention using soft wood like a paint stick instead of a strop. Do you still put some compound on it?
 
Randydb said:
I was impressed with how quickly it all went considering these knives didn't have their secondary bevels on them yet. And I was really excited by how sharp they were with so little effort. This has completely changed my knife sharpening routines.

I have seen a few people mention using soft wood like a paint stick instead of a strop. Do you still put some compound on it?
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I use green chrome compound for regular blades and diamond paste for super steels. All of this stuff is quick and cheap so you aren't out much if you don't like it.
 
A.McPherson said:
Razors have a different geometry than most knives, and are sharpened differently.
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That doesn't address styling shears, which have an edge angle around 45° inclusive and easily shave (single blade, disassembled) when sharp. Something doesn't add up.
 
I use a 250x diamond plate to get the initial bevel set, then use an edge pro. Consistent, repeatable results. Last step is strop on a loaded leather strop with a solid backing. The only downside is the cost of the edge pro replacement stones, but I will be ordering stones from falcon this week and gluing them to the backing plates I already have. I want to try sic stones for high allow steels.
 
Willie71 said:
The only downside is the cost of the edge pro replacement stones, but I will be ordering stones from falcon this week and gluing them to the backing plates I already have. I want to try sic stones for high allow steels.
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I believe those are just alternately branded BORIDE stones; they share the same contact address of 2615 Aero Park Drive.

I recommend purchasing through Mold Shop Tools where you don't need to order 12 at a time, pricing is superior, and customer service has been very good.
 
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