Tips for sharpening

Justin Schmidt

Justin Schmidt

Joined
Feb 18, 2016
Messages
2,209
So after you complete the finish and the knife is at it's final dimensions how do you go about sharpening the blade? I was thinking of a coarse diamond stone and making a leather strip. I saw someone use a 220g on the slack portion. Well first what would "final dimensions " be before you sharpen? How do you sharpen it? Thanks again
 
I generally take a used, but not useless 320 grit belt, Run it slow so as not to overheat the blade and taper the cutting edge. I take one stroke per side cooling in water between strokes, repeating until I can no longer detect light reflecting off the edge. I then go to a medium Spyderco ceramic stone. I take 6 or seven strokes on each edge then check for burrs. Once I get a burr, I take a few strokes on the stone with the burr down until it dissappears. I usually chase the burr back and forth a few times until I can no longer feel it. Then to a strop (board with leather split loaded with green chrome compound). Watching the marks the edge leaves in the strop, I continue until all groves are gone. I then cut paper, looking for the spots on the blade where the paperpulp sticks, these are rough or dull spots. Then back to the stone or strop depending on the size of the spots to repeat the process.

I'm sure this is not the fastest way to sharpen but it works well and produces a wonderfully sharp edge.
Jim A.
 
I get the edge as close to "sharp" as I'm comfortable with before I sharpen.
I use a Hapstone system, but if your on a budget a Lansky multi stone system is the same principle and pretty foolproof.
Someday I'll put my big boy pants on and sharpen on my grinder, but not today.
 
There are as many ways to sharpen as there are people who sharpen. The important thing is to not overheat the edge and to have the correct geometry for the purpose of the knife. Slicers get thin edges, choppers get slightly thicker edges. You can put the initial edge on with water stones, diamond stones, ceramic rods, India stones, abrasive belts, guided sharpening systems like the Lansky system or something else. Once you raise a wire edge ( meaning the bevel on one side has met the bevel on the other side) repeat it as many times as you need to progress to the final grit level you want to take it. At this point you are only half done. Then you need to strop the edge. This removes the wire edge and reveals the true cutting edge. This also can be done many ways. You can strop on a piece of vegetable tanned leather mounted to a wood block with or without buffing compound, you can strop on cardboard, balsa wood, your hand, the frosted edge of your car window, the bottom of a ceramic coffee cup, a leather belt on your 2x72 grinder, a buffer, a cardboard or plywood wheel on your buffer.....you get the idea. Use edge trailing strokes and raise the handle a bit as you approach the tip of the blade. Do not feel you have to put very high grit polished edges on your blade. For most uses a 1200X finish is plenty sharp and toothy enough to cut well.
 
For my utility knives I use my belt grinder, either with a flat platen or a leather backed flat platen for more robust convexed edges. I seldom go above 600 grit and then strop.

I run my grinder slow and with water. It will very fast give me a edge that will easily push cut phone book paper.

My smaller hunters will usually get a 18 DPS convexed edge (and they are usually taken down to about 0,1-0,2mm before sharpening).

On my kitchen knives I usually spend a little more time, and use my Wicked Edge. And end up from 1000 grit to a couple of microns based on need and mood.

Wicked sharp, blades well worked on the WEPS will accomplish the HHT.
 
over the years I've tried all kinds of methods, and I mean a LOT of different methods. I'm no expert, but what I do now that i have a 2x72 grinder and variable speed driver is so fast and effective I stopped everything else;
1. use 220 belt, driven 1/3 speed, use slack side @ top. since there is a slight crown on wheels slightly angle the knife depending on what side i'm sharpening- it usually only takes 2-3 passes on each side of the blade to visually watch the burr appear. then once very lightly drag across a soft wood to take super fine burr off (can use cork, I use mdf that my grinder is mounted to)
2. use 2x72 leather belt on my grinder loaded with green compound. 2-3 passes. done

that is it, takes all of 3-4 min
 
knoxknives said:
over the years I've tried all kinds of methods, and I mean a LOT of different methods. I'm no expert, but what I do now that i have a 2x72 grinder and variable speed driver is so fast and effective I stopped everything else;
1. use 220 belt, driven 1/3 speed, use slack side @ top. since there is a slight crown on wheels slightly angle the knife depending on what side i'm sharpening- it usually only takes 2-3 passes on each side of the blade to visually watch the burr appear. then once very lightly drag across a soft wood to take super fine burr off (can use cork, I use mdf that my grinder is mounted to)
2. use 2x72 leather belt on my grinder loaded with green compound. 2-3 passes. done

that is it, takes all of 3-4 min
Click to expand...
This is exactly what I do.
 
Before starting to sharpen a blade make sure the bevels and all upper places are completely finished. The handle should be 100% done, too. If making a sheath, do that before sharpening.

The edge should be between .010" and nearly sharp ( often called a zero edge) .... depending on how rough the use will be. Edge angle is determined by use, too. The harder the use the higher the angle. It can go from 10° per side on a fillet blade to 30° per side for a brush whacker. A good starting place is around 20° per side for general use knives.

The degree of fineness of the edge will also vary depending on use. Many of us take the edge of a utility knife or hunter to a 220 grit finish on a slow belt and give the edges one quick pass on the buffer with white polish. This makes a very aggressive edge and cuts meat and most stuff well. A smoother finish to 400 grit does well on many kitchen knives. Fine slicers like sashimi knives are often taken to 1000 grit then polished. Japanese sword edges may be finished to as high as 14,000 grit and highly polished.

The final step on any edge is to polish off the "wire" ( burr) with a strop or buffer. The buffer is a professional tool. and can remove fingers instantly when polishing an edge, so I do not recommend it for anyone who is not very experienced making knives. The better, and many say the best, way of removing the wire and polishing the edge is on a leather strop board. Glue a 12" long strip of 2" wide leather to a flat wooden board. I like to put the smooth ( grain) side up, but some do it the other way around. I don't think it makes all that much difference. Make a handle on one end of the board to hold firmly. This paddle will last many years if kept clean and free of stray grit ... so keep it in a sleeve or zip-lock bag when not in use. The silliest thing I see in many shop photos is the strop sitting on the bench next to the grinder. Charge with green chrome, white rouge, or diamond paste. If using diamond paste, 600 grit is good. You can make a second paddle for 1200 grit diamond if you like a nice shiny edge.

One rule of sharpening is the same as grinding, increase the fineness of the stone/media by about double each step. Going in bigger jumps leaves a lot of microscopic ( or not so invisible) grooves on the edge. A good first cut is 220 grit, then 400-600, and if a fine polish is desired 1000-1200. Above that is not going to gain anything on any normal knife.

Edge shape is also a consideration in sharpening. The edge can be a flat "V" , which is done by keeping the blade at a steady angle against a stone or hard flat platen. If the blade is rocked/lifted as the edge is ground, or done against a softer backing on the platen or a slack belt, then it makes a convex edge. These edges are a bit tougher, and work well to extend the edge on a lower angle blade used for fine cutting. Effectively, the first .0001" or so of the blade edge may be 30° per side and as the edge curves into to 15° per side. The degree of backing softness or slack in the belt will determine how well it is convexed. Hard rubber, like a mouse pad, and firm cork are good materials. A graphite platen backing also works excellent when paired with a 400 grit belt.
 
Stacy E. Apelt - Bladesmith said:
Before starting to sharpen a blade make sure the bevels and all upper places are completely finished. The handle should be 100% done, too. If making a sheath, do that before sharpening.

The edge should be between .010" and nearly sharp ( often called a zero edge) .... depending on how rough the use will be. Edge angle is determined by use, too. The harder the use the higher the angle. It can go from 10° per side on a fillet blade to 30° per side for a brush whacker. A good starting place is around 20° per side for general use knives.

The degree of fineness of the edge will also vary depending on use. Many of us take the edge of a utility knife or hunter to a 220 grit finish on a slow belt and give the edges one quick pass on the buffer with white polish. This makes a very aggressive edge and cuts meat and most stuff well. A smoother finish to 400 grit does well on many kitchen knives. Fine slicers like sashimi knives are often taken to 1000 grit then polished. Japanese sword edges may be finished to as high as 14,000 grit and highly polished.

The final step on any edge is to polish off the "wire" ( burr) with a strop or buffer. The buffer is a professional tool. and can remove fingers instantly when polishing an edge, so I do not recommend it for anyone who is not very experienced making knives. The better, and many say the best, way of removing the wire and polishing the edge is on a leather strop board. Glue a 12" long strip of 2" wide leather to a flat wooden board. I like to put the smooth ( grain) side up, but some do it the other way around. I don't think it makes all that much difference. Make a handle on one end of the board to hold firmly. This paddle will last many years if kept clean and free of stray grit ... so keep it in a sleeve or zip-lock bag when not in use. The silliest thing I see in many shop photos is the strop sitting on the bench next to the grinder. Charge with green chrome, white rouge, or diamond paste. If using diamond paste, 600 grit is good. You can make a second paddle for 1200 grit diamond if you like a nice shiny edge.

One rule of sharpening is the same as grinding, increase the fineness of the stone/media by about double each step. Going in bigger jumps leaves a lot of microscopic ( or not so invisible) grooves on the edge. A good first cut is 220 grit, then 400-600, and if a fine polish is desired 1000-1200. Above that is not going to gain anything on any normal knife.

Edge shape is also a consideration in sharpening. The edge can be a flat "V" , which is done by keeping the blade at a steady angle against a stone or hard flat platen. If the blade is rocked/lifted as the edge is ground, or done against a softer backing on the platen or a slack belt, then it makes a convex edge. These edges are a bit tougher, and work well to extend the edge on a lower angle blade used for fine cutting. Effectively, the first .0001" or so of the blade edge may be 30° per side and as the edge curves into to 15° per side. The degree of backing softness or slack in the belt will determine how well it is convexed. Hard rubber, like a mouse pad, and firm cork are good materials. A graphite platen backing also works excellent when paired with a 400 grit belt.
Click to expand...
EXACTLY what I was looking for. Thanks for chiming in Stacy. Your advice is always appreciated.
Thank you everyone for the tips. This seems to be a step some how toos forget.

Side question. Will the green buffing compound from CA work for a leather strop?
 
It looks like I'm a bit late on this thread but I figure I'll ask anyway. How do you resharpen the convex edge? Is it like sharpening a convex grind with sandpaper on leather and then a strop? Most folks seem to be a little hesitant to sharpen that way and prefer to use a stone or similar sharpener that would produce a flat edge instead of a convex edge.
 
I put convex edges on my knives using the slack belt on my 2x72 grinder. To resharpen the convex edges I go back to the grinder. A knife shouldn't be allowed to go dull if possible. Using a steel or stropping regularly will increase the life of and edge and keep it in ready to use condition. But when the edge is damaged or dull it should only take a few minutes on the belt to bring it back to life.
 
So it's essentially like maintaining a fill convex edge.

I agree an edge shouldn't be allowed to go completely dull, but sometimes when you give/sell someone a knife they don't always have the best knife care practices (cough cough, an electric pull through sharpener...)

Thanks!
 
i4Marc said:
It just removes the possibility of hurting yourself While making and fitting the sheath to the knife. If sharpening is the last thing you do before the knife goes to its new home there is little risk.
Click to expand...

Thanks Marc. That makes sense, but (not being argumentative here) I've made about 6 sheaths so far and can't see how that could happen without being extremely careless. (An example specific to me would be that I have a habit and great reflexes thanks to my many years of being a hockey goalie in college, to, without thinking, reflexively catch things that slip out of my hands. I often catch them to the amazement of my friends, and that type of injury could definitely happen in that situation...

~billyO
 
Good reflexes are certainly a benefit however they won't help you in every situation. In my particular example, I was testing the fit of the knife in a sheath I had just completed. The fit was a bit tight. In fact, the knife was stuck in the sheath. So I gripped the sheath in what I thought was a safe location and gave a good tug. Well, because of the way the front of the sheath was relieved (to offer a better grip of the handle when withdrawing the knife) My hand wasn't in a safe place. When the knife came out it cut the finger. Even good reflexes wouldn't have saved me that trip to the ER for a few stitches. If the knife hadn't been sharpened it wouldn't have been an issue. I thought I was being careful but I overlooked something and the accident happened. Whatever the circumstances are of anyone's individual scenario, the possibilities exist for contact of the blade edge with the person handling the knife. A maker might say "I've sharpened 2,319 knives before making my sheaths and never had an incident". Ok, that is a good run. Even so, you still don't know what fate has in store for #2,320. So don't tempt it. Stacy may have had other reasons but I think it's just a safety precaution.
 
Convex edges are hard to reproduce, too many variables. It will make an edge sharp, agreed.


If I believe one thing about sharpening it's that repeating the same angle each time is a must. How you do this is up to you.
If degree wedges are used on a diamond plate, the same edge can be produced each time the knife needs sharpened. Using degree wedges sharpening an edge will be faster, take less time, each time the blade is sharpened, for the edge bevel is known and is being repeated each time, whether sharpening, stropping or touching up a nick. ad
If you use degree wedges, or have a way to control angle; stay away from strops. The will round the straightened edge, turn it over, distort it.
I stop by lifting the blade a couple of degrees and making a pass. I use an ERU when I have one t

What ever you do find a method that you can reproduce. If you can only get the knife sharpened once, with your technique, what use is it?

Fred
 
weo said:
Thanks Marc. That makes sense, but (not being argumentative here) I've made about 6 sheaths so far and can't see how that could happen without being extremely careless. (An example specific to me would be that I have a habit and great reflexes thanks to my many years of being a hockey goalie in college, to, without thinking, reflexively catch things that slip out of my hands. I often catch them to the amazement of my friends, and that type of injury could definitely happen in that situation...

~billyO
Click to expand...

I have a scar around my left middle finger and only one patent artery past my knuckle due to trying to catch a falling knife.
 
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