Improving sharpening skills

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registrationsucks

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Jan 20, 2006
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Using alternating strokes on a King 800 grit waterstone, and then removing the burr with two light strokes at an 45 degree angle on a spyderco medium benchstone, I can get an edge that will shave and slice paper.

I cannot seem to get an edge that will pushcut paper at all. I'll move up to a 1200 grit waterstone, but the edge doesn't seem to get any better. I'll then try medium or fine spyderco benchstones, but the best edge that I can get is one that will slice, but not push cut copy paper.

Does this sound like a problem with maintaining a consitant angle or using uneven pressure?

Any insights things that I can try?

Thanks!
 
By saying alternating strokes, do you mean 1 stroke on one side then a stroke on the other? If so you shouldn't get a burr.
 
db said:
By saying alternating strokes, do you mean 1 stroke on one side then a stroke on the other? If so you shouldn't get a burr.
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I usually do 1 stroke per side and then switch. I assumed I had some type of burr because the edge gets a lot better when I do a couple light strokes on a finer stone at a greater angle.

Should I sharpen one side till I raise a burr that I can feel and then start sharpening the other side with finer stones?

Thanks!
 
What I heard, and what I do is to sharpen one side completely, then do the other side.

Thank you for the link Joe Dirt, I'm going to read it, too. Thanks again.
Good luck with your sharpening, regislationsucks.
 
registrationsucks said:
Using alternating strokes on a King 800 grit waterstone, and then removing the burr with two light strokes at an 45 degree angle on a spyderco medium benchstone, I can get an edge that will shave and slice paper.

I cannot seem to get an edge that will pushcut paper at all. I'll move up to a 1200 grit waterstone, but the edge doesn't seem to get any better. I'll then try medium or fine spyderco benchstones, but the best edge that I can get is one that will slice, but not push cut copy paper.

Does this sound like a problem with maintaining a consitant angle or using uneven pressure?

Any insights things that I can try?

Thanks!
Click to expand...

It sounds sharp to me. It may just be that your secondary and primary bevels are set at a larger angle (40-45 degrees total) which while still very sharp are not the ideal angle for push cutting paper.

You might look at getting a strop/hone to put a final polish on the edge and see if this accomplishes the push cutting.

http://www.drsharpening.com/leatherhone.html
 
No you don't need to use the burr method. There are many better sharpeners than me that don't get a burr. However, it is a good way to tell if your reaching the edge if your not sure. I wouldn't sharpen on one side only until a burr forms though. If you do that you can move the edge off center on a dull knife. try and do the same amount of sharpening on both sides, exsample do 50 strokes on one side and then switch and do 50 on the other, keep doing that until a burr forms along the hole edge. Use what ever number you want 20,30 or 80 its your choice. Or doing what your doing now alternating strokes works just as well if not better because you don't have to remove any burr. Make sure your sharp with the coarse stome before you move to the finer stones and I'd keep the same angle for both.
 
The only advice I can give you is that your ultimate goal is to form a zero point along the entire edge. Anything that takes you away from that goal of a 0.000000 micron edge is bad. Of course in reality the best you can attain with sharpening gear afforded to us mere mortals is 0.1-0.35 microns.

A few things: Its theoretically impossible to make a knife sharp with abrasives without forming a burr. Even if it is microscopic. But a burr on the final product is bad. Remove it with extremely light and even strokes on a very fine abrasive such as a chromium oxide laden strop. A burr is basically a folded over edge, and this increases the width of your edge.

Once you have that final, straight edge, it should be sharp.

Easier said then done though...

And another thing, I've never gotten a knife "razor sharp" like some of the guys on this forum have (laugh laugh sarcasm sarcasm). The sharpest I've ever gotten it is about half as sharp as a disposable razor blade. So you're probably better off listening to them.
 
DGG said:
It sounds sharp to me.
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Just being able to slice paper is actually fairly blunt, on most cardboard cutting comparisons I run, the blades blunt down to 5-10% of optimal and they can still slice newsprint fairly close to the holding point. There was a time when I considered that sharp as well though.

It may just be that your secondary and primary bevels are set at a larger angle (40-45 degrees total) which while still very sharp are not the ideal angle for push cutting paper.
Click to expand...

You can do this even at a very obtuse angle, 20 degrees per side isn't a problem assuming you mean push cut the newsprint close to where it is held and the tension is high.

db said:
By saying alternating strokes, do you mean 1 stroke on one side then a stroke on the other? If so you shouldn't get a burr.
Click to expand...

Lots of steels will still burr like that, it depends highly on the condition of the edge before honing, the nature of the steel (hardness, carbide, grain), and pressure on the hone and aggression of abrasive.

registrationsucks said:
Using alternating strokes on a King 800 grit waterstone, and then removing the burr with two light strokes at an 45 degree angle on a spyderco medium benchstone, I can get an edge that will shave and slice paper.
Click to expand...

The medium rods will push cut at 20, it will be rough though and catchy, but they should bite into the paper at a 90, if you angle the blade it should do it readily, the fine rods will raise this to the point where you can cut curves in the paper with ease, Sal Glesser does a demo where he cuts a circle out of a piece.

Does this sound like a problem with maintaining a consitant angle or using uneven pressure?
Click to expand...

Possible problems :

1) not enough work done with the coarse stones and scratches ar persisting, you can see this under magnification, the edge will be irregular and it will take *forever* to improve on the fine stones

2) grinding parallel to the edge causing breakouts - are you using circular motions?

3) the edge is burred and won't shave smoothly on both sides as there is a side bias, grind it off, rehone the edge and recheck

4) the knife is buggered, bad grain or segregated carbides - not much to do here, use it as a beater

-Cliff
 
Wanted to add that I only use a Lansky with 3 different stones and an old leather belt as a strop with NO compound and my knives will shave with no problems. I figure that's about as good as I will ever need. :)
 
Cliff I didn't know grinding parallel to the edge caused breakouts, that would explain how when sharpening on a 400-600 grit stone I got these massive chips in the edge. So sharpening in circular motions can cause breakouts?

Useful info to file away, thanks!
 
I take it I am losing out on a lot of potential performance by using the two strokes on a medium stone at 45 degrees. Is there a better way to remove this small burr (or is it a wired edge) without sacrificing performance?

I've tried to feel the edge of blade in the past to determine which side I should sharpen, but I can never tell a difference.

Thanks for all the replies so far!
 
ghost squire said:
So sharpening in circular motions can cause breakouts?
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The easiest way to understand this is to take a piece of wood, a 2x4 will do, and a few wood gouges and form the edge by carving out sections running perpendicular to the edge and noting how it forms and then repeat by running parallel to the edge and watch the mess that develops. While parallel scratches can form micro-teeth, the teeth will oppose each other, not cut uniformly, and be very weak to impacts because loads on them will be lateral instead of compressive.

If you are going to use this as a sharpening step it works fine for shaping, but the final edge should be honed either at 90 or a close angle to the hone for maximal edge retention. Some people use the circles and don't have the problem of breakouts because they spend a long time and go to very high finishes and eventually there is no micro-teeth and all the scratches are polished out. This takes a long time though and you have to polish the entire edge bevel, you can't effectively micro-bevel such an edge.

registrationsucks said:
I take it I am losing out on a lot of potential performance by using the two strokes on a medium stone at 45 degrees.
Click to expand...

Not really, this is how Goddard does it, he doesn't go quite that high, but is much more obtuse than his actual sharpening angle. If you want to get the ultimate cutting performance you can cut these strokes off by light honing at the origional angle again. It should only take a minimal of passes if you are micro-beveling.

-Cliff
 
Cliff are you saying the scratch patern should be 90 degrees from the edge? I find I like a 45 degree scratch patern the most. It kind of works like a saw pushes easier and really digs in on a pull. I don't sharpen at as low of an angle as you do I sharpen someplace around 10 to 13 per side. I've been really happy with the preformance I get with the 45 but I haven't played with scratch patern angles in a long time to really remember the difference.
 
Ninety would be most versatile and durable over a broad range of tasks, angled micro-teeth are more powerful at some work but exceptionally weak at others, the same general ideal can be found in saws, compare swede saw patterns to the japanese ones for example. Knives also in general do push cuts, and angled micro teeth are really weak to push cuts because they load the teeth laterally vs compressive and lateral deformations are many times weaker. Of course if you mainly do draw cuts towards you (or away from you), an angle bias can be useful and if you go to a really high polish it likely doesn't matter as there is next to no micro-teeth anyway.

-Cliff
 
Interesting... What about if you do what I do: I use a 90 degree angle to the stone with the knife, but I slide the blade of the knife along that angle to sharpen all parts of that side of the blade in one swipe. I don't know if I explained that clear enough....

Should I switch to just doing sections of the blade at a time? I'm not noticing micro chips but I do polish to quite a high level. I'm just wondering if I'm doing it as efficiently and as well as I could.
 
Common japanese sharpening is done like that in sections, I generally don't do that on small blades, as I find it hard to keep the angle consistent, but it is probably more optimal. On smaller blades assuming the stone length is large the scratch patterns will be strongly perpendicular to the edge even with a draw, you can see this under magnification.

-Cliff
 
That makes sense. I didn't know the Japanese sharpened most of their blades like that... It must require quite some degree of skill.
 
there's a couple of chapters at the end of "The Complete Bladesmith" (by Hrisoulas) that detail the process.
 
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