sharpening: a simple hypothesis.

[bridger berdel]

and by no means comprehensive :)

in a nutshell: the greater the angular difference between bevels the less honing time needed, or the greater the jump in grits feasible.


so, if you wish to hone a flat bevel with no microbevel you will spend lots of time honing at the finer grits, just polishing the bevel. it looks great but puts unnecessary wear on your stones and your elbows.

if you start with a really low primary bevel you can probably jump straight to your finishing stone. kind of crude looking and perhaps a bit fragile.

use a really high microbevel and the time on the finish stone will be minimized but the chisel may not perform well for paring despite being sharp.

[Jim Koepke]

To me this seems more of an opinion than fact.

Often for me there is a very quick touch up of the bevel on my 1000 stone to remove a nick or better define the bevel. A few strokes on my 4000 stone and then a few more on my 8000 stone. One time when going directly to the 8000 from the 1000, removing the burr left a scratch on the 8000.

If the blade just needs a touch up, it is 4000 then 8000. Usually the few steps from the bench to the stones, then from the stones to the strop and then back to the bench takes longer than the time spent on the stones. My oil stones may take a bit longer.

Maybe there is time saved by not having to use a honing guide when working a flat bevel freehand.

Of course, I am usually not in a race to see how fast something can be sharpened.

Besides, when the secondary bevel grows over time it is like honing a single flat bevel.

Flat bevel, hollow ground bevel, back bevel, secondary bevel, tertiary bevels, convex bevels ad infinitum, what ever works for the individual is the best way to proceed.

When an edged tool isn't working to do what is wanted of it when it is time to look for another way.

There is more than one way to skin a cat and none of them call for a dull blade.

jtk

[george wilson]

For PETE'S SAKE. NOT another SHARPENING THREAD. Give it up guys. Just learn how to use your tools!! Those sharp tools aren't going to jump up and make masterpieces all by themselves.

I just watched a video of a guy who cut a pretty decent mortise through a 6" log with a STONE AXE. And I don't mean FANCY stone like obsidian or flint. I mean plain old gray stone.

[Rob Luter]

Is there anyone else who finds it remarkable to hear stone axe and video in the same post?

[Andrew Hughes]

I see you point Rob.
Almost as unbelievable as a antique digital grandfather clock.

Aj

[Luke Dupont]

For PETE'S SAKE. NOT another SHARPENING THREAD. Give it up guys. Just learn how to use your tools!! Those sharp tools aren't going to jump up and make masterpieces all by themselves.

I just watched a video of a guy who cut a pretty decent mortise through a 6" log with a STONE AXE. And I don't mean FANCY stone like obsidian or flint. I mean plain old gray stone.

And someone didn't like my crappy mild-steel chisel :(
It got me back to work quickly and accomplished its task, though!

I do share your sentiment, but I think there's something to be said for learning and exploring different facets of a particular subject in-depth. I've learned quite a bit about both sharpening media and steel from these discussions. It's better to get a broad/more complete understanding of something than to just blindly subscribe to/follow popular trends, in my opinion. As an experienced person, I'm sure all these discussions seem kind of silly to you, and maybe they are, but there those of us still exploring these things for the first time. In the end, it doesn't matter as long as you can get back to work with sharp tools efficiently, but I do think that spending the time to explore different media and methods is good, because you might find a method/media that suits you better than the one you had previously subscribed to, and you might even learn a thing or two in the long term.

By the way! I'm interested in the stone chisel/axe video. Link please?

[Pat Barry]

For PETE'S SAKE. NOT another SHARPENING THREAD. Give it up guys. Just learn how to use your tools!! Those sharp tools aren't going to jump up and make masterpieces all by themselves.

I just watched a video of a guy who cut a pretty decent mortise through a 6" log with a STONE AXE. And I don't mean FANCY stone like obsidian or flint. I mean plain old gray stone.
So George, since this is a sharpening thread, did this fellow go into detail as to his stone axe sharpening methods? Were they in accordance with the theory offered in this thread? I'm lost as to why you went so far off topic.

[Karl Fife]

If you've ever seen David Charlesworth's sharpening videos, you'll notice that he takes a moment to increase the honing angle slightly between stones. This saves time removing metal because the next stone only contacts the very edge of the blade, not the entire plane left by the previous stone. This saves time. David's method is essentially a more refined version of what you're hypothesizing here. You owe it to yourself to watch his sharpening videos. His instruction is absolutely without equal (IMHO).

[Luke Dupont]

I do want to address the original point by saying that there is no best method. It depends on your tools, your sharpening media, the kind of geometry you're after, etc. etc.

Japanese tools are easy to sharpen the entire bevel, because they're laminated to a soft back. So why not keep things simple?

How about if you hollow ground, or sharpen in a cambered fashion, or with a convex bevel? How about the person who starts on a coarser stone as opposed to a finer one?

What kind of steel are you using? What media are you sharpening with? Are you using a jig, or free hand? What's your work-space like? Are you using waterstones, oil-stones, diamonds, a strop? Do you need to do any presoaking or flattening of yourstones before getting to work? Do you mind doing that stuff? What is your personal preference and is most enjoyable for you? What fits your work flow?

Ultimately, many of these things are so subjective as to hardly be worth arguing over. Someone might be convinced that hollow ground is the way to go, for instance, but does that mean I should go out and buy a big grinder to lug around, try to find a place for in a closet somewhere, and get out every time I have to use it because I work in an apartment without a dedicated work space?

There's no one-size fits all approach.

[george wilson]

Sorry. I should have said nothing. If you all want to re discuss sharpening again and again, it is up to you. That is where your heads are,I suppose. (Well,obviously they are,or the subject would not keep cropping up!):)

[steven c newman]

One rule might apply to sharpening... K.I. S., S.

And by keeping things simple, you can get back to work sooner, less errors creep into the process, Your hands and arms get used to doing the same things over and over, almost habit forming. Then, you can find other things to over-think about.

Saw a gal walking into the store today....T-shirt read " Gym Hair, and I don't care" maybe mine would read....Shoptime, and I don't care...

Too much OCD about getting the perfect edge......

[allen long]

Quick question. When folks here refer to a micro bevel, is this the same thing as a secondary bevel or a something else like a tertiary bevel? (And yes I am asking because I honestly don't know )

[bridger berdel]

It looks like some of you thought that I was making a qualitative judgement of some kind. I wasn't

[david charlesworth]

Thanks Karl.

Allen,

you can see my chisel sharpening method on You Tube, https://www.youtube.com/watch?v=un-DVvXnCeA

I think I use a tertiary bevel for the 8 or 10,000 grit polishing stone!

The routine is ; grind at 25 degrees, get a small wire edge at 33 degrees on an 8oogrit stone, Shorten the projection by about 2 mm, and polish the tip at 35 degrees. (This is for Japanese and A2 chisels).

The slight change of angle means only three or four polishing strokes.

The 800 bevel is kept narrow and I regrind about every 7-10 sharpenings.

I think Bridger has a reasonable theory.

best wishes,

David

[bridger berdel]

Sorry. I should have said nothing. If you all want to re discuss sharpening again and again, it is up to you. That is where your heads are,I suppose. (Well,obviously they are,or the subject would not keep cropping up!):)


I don't know what it is about sharpening that gets so much attention. It probably has something to do with the universality of it- every craftsperson, whether a chef or a surgeon or a woodworker needs sharp tools. sharpening takes time, which means it either takes your attention away from the "work" or it becomes the work.


I teach sharpening at the local woodcraft. I encourage keeping the time spent sharpening to a minimum and staying focused on the woodworking. getting too focused on the sharpening will take you down a rabbit hole with no bottom.

do as I say, not as I do :)

[bridger berdel]

If you've ever seen David Charlesworth's sharpening videos, you'll notice that he takes a moment to increase the honing angle slightly between stones. This saves time removing metal because the next stone only contacts the very edge of the blade, not the entire plane left by the previous stone. This saves time. David's method is essentially a more refined version of what you're hypothesizing here. You owe it to yourself to watch his sharpening videos. His instruction is absolutely without equal (IMHO).


this is not a refinement of a hypothesis, it's a practical application of it.

I enjoy DC's careful, measured speaking style. while I don't agree with everything he says he obviously has a great deal of knowledge and is generous with it.

[Robert Engel]

BB - you are correct. Hollow grinding is another way, but a microbevel is an "ABC" of sharpening.


You'll still get an argument!!;)

[bridger berdel]

Quick question. When folks here refer to a micro bevel, is this the same thing as a secondary bevel or a something else like a tertiary bevel? (And yes I am asking because I honestly don't know )


a microbevel is just a bevel that is significantly narrower than the bevel preceding it. so if you grind a chisel at one angle to produce a bevel about an inch wide, then hone a second bevel that ends up about 1/16" wide, the second bevel is the microbevel.

[ken hatch]

I don't know what it is about sharpening that gets so much attention. It probably has something to do with the universality of it- every craftsperson, whether a chef or a surgeon or a woodworker needs sharp tools. sharpening takes time, which means it either takes your attention away from the "work" or it becomes the work.


I teach sharpening at the local woodcraft. I encourage keeping the time spent sharpening to a minimum and staying focused on the woodworking. getting too focused on the sharpening will take you down a rabbit hole with no bottom.

do as I say, not as I do :)

Guilty, guilty as charged:). When time is short and/or energy is low there can be great pleasure putting iron to stone or leather. There is also pleasure in finding and understanding the differences between stones and steels. I sometimes wonder do I woodwork so I can sharpen or is it in the correct order sharpen so I can woodwork. Most of the time the priorities are in the correct order but there are times:p.

ken

[bridger berdel]

BB - you are correct. Hollow grinding is another way, but a microbevel is an "ABC" of sharpening.


You'll still get an argument!!;)


with the commonly proposed scenario of hollow grinding, where the bevel "clicks" down on the stone- the flat honed at the edge is a "microbevel" relative to the ground surface it intersects. the flat honed at the heel of the bevel is a reference surface and in my opinion wasted effort. however, it isn't that much effort wasted, so if it is useful, use it.

[Patrick Chase]

and by no means comprehensive :)

in a nutshell: the greater the angular difference between bevels the less honing time needed, or the greater the jump in grits feasible.

Since nobody has said this: Yes, I think this is true, and there's a reasonably convincing argument for why it should be so.

In order to "successfully jump" from grit X to grit Y, the scrartch pattern from Y has to completely replace the pattern from X at the cutting edge (it doesn't matter what happens away from the edge). This means that stone Y has to remove a thickness of material at the edge equal to the scratch depth from stone X at the edge. Let's call this thickness t_X.

If the angles are the same, then the cross-sectional area of material that must be removed is simply t_X*h, where h is the height of the bevel measured along its face (not perpendicular to the blade back).

If the angles are different, then instead of removing a slab of contant thickness t_X you only need to remove a triangular sliver of material that's t_X wide at the base. The higher the difference in angle, the shorter that triangle will be and the less total material you have to remove to completely replace the stone X's scratches at the cutting edge.

Alternatively, the higher the angle the more thickness t_X you can remove at the edge within any given time/volume constraint, which means that you can start with a coarser stone that leaves deeper scratches (your original theory).

Seems pretty straightforward and borderline-inarguable...

[Warren Mickley]

When you consider the time it takes to use microbevels, you must consider the sharpening as a whole not just number of strokes on a given stone. I recently watched a chisel sharpening video of a guy who took just four strokes (ten seconds) on an 800 grit stone before moving on. A time saver? The four strokes were done with a jig and only cut with the back stroke (the jig being lifted between strokes). And because of the jig the strokes were not full length. Without the jig a worker can take two or three dozen forward and back strokes in the same ten seconds. Full length strokes. That is somewhere in the neighborhood of 20 times the length of travel on the stone. And without a jig you can bring more pressure to bear on the stone.

And there is more. Because the jig only uses the center of the stone, the stone had to be flattened from the previous use. Between stone flattening and mounting the the chisel in the jig, 35 seconds was consumed. And after doing the four strokes on the coarse stone, the fine stone had to be flattened and the jig cleaned off and adjusted for a higher bevel, consuming another 39 seconds before actual abrasion was started. An awful lot of fooling around time.

I have watched guys do micro bevels freehand also. It is considerably faster, but not nearly so precise. Guys will say "and then I raise the chisel about one degree". When you watch they raise it five degrees or more. Many are honing in the 40 degree range. Frankly a chisel with a flat bevel is nicer to work with.

[Derek Cohen]

Bloody sharpening threads!

My system works for me. I cannot guarantee it will be the best method for you, but it is the most efficient system I have tried to date.

The reason I hollow grind:

1. It reduces the amount of steel to hone to a minimum as it works a microbevel. That speeds up honing time and also reduces the demands on the honing media.

For reference, my definition of a microbevel is not a bevel at a higher angle to the primary bevel. It is a really tiny bevel. A bevel at a higher angle is a secondary bevel.

2. I hone freehand flat on the hollow. There is no lifting to create a secondary bevel. The microbevel is coplanar with the primary bevel. The condition here is that one grinds the hollow at the desired angle. This is easy to do.

The advantage of a honing guide lies in creating a repeatable bevel angle. A repeatable bevel angle means that you do not start from scratch each time, and the bevel angle does not grown higher. It stays the same each time you hone. As important sharpening is, a good sharpening system must take into account re-sharpening - do you start from scratch the next time you hone the blade, or can you just repeat what you did before?

Honing directly on the hollow is the freehand equivalent of a honing guide, except that it is faster, and you can use the whole stone.

If you are going to hollow grind, then the SOTA in hollow grinding is a CBN wheel. This needs no upkeep and the hollow does not change. An even hollow also means less metal to straighten, and less time needed to hone.

Here is a typical hollow grind on a chisel, with the microbevel (one microbevel only) honed to 0.5 microns. This involved 2-3 stones, with a few strokes each only. About 30 seconds in all.

http://www.inthewoodshop.com/WoodworkTechniques/UltimateGrindingSharpeningSetUp_html_71b2c2d0.jpg

I've posted this a few times, but for those who have not read it for consideration:

http://www.inthewoodshop.com/WoodworkTechniques/UltimateGrindingSharpeningSetUp.html (http://www.inthewoodshop.com/WoodworkTechniques/UltimateGrindingSharpeningSetUp.html)

Works for me.

Regards from Perth

Derek

[Luke Dupont]

When you consider the time it takes to use microbevels, you must consider the sharpening as a whole not just number of strokes on a given stone. I recently watched a chisel sharpening video of a guy who took just four strokes (ten seconds) on an 800 grit stone before moving on. A time saver? The four strokes were done with a jig and only cut with the back stroke (the jig being lifted between strokes). And because of the jig the strokes were not full length. Without the jig a worker can take two or three dozen forward and back strokes in the same ten seconds. Full length strokes. That is somewhere in the neighborhood of 20 times the length of travel on the stone. And without a jig you can bring more pressure to bear on the stone.

And there is more. Because the jig only uses the center of the stone, the stone had to be flattened from the previous use. Between stone flattening and mounting the the chisel in the jig, 35 seconds was consumed. And after doing the four strokes on the coarse stone, the fine stone had to be flattened and the jig cleaned off and adjusted for a higher bevel, consuming another 39 seconds before actual abrasion was started. An awful lot of fooling around time.

I have watched guys do micro bevels freehand also. It is considerably faster, but not nearly so precise. Guys will say "and then I raise the chisel about one degree". When you watch they raise it five degrees or more. Many are honing in the 40 degree range. Frankly a chisel with a flat bevel is nicer to work with.

All the above are excellent points, and why I never bought into microbevels. I sharpen free hand because it's fast, easy, and intuitive, more adaptive, and more enjoyable. And I don't use micro-bevels because it means more grinding on the flat the next time you sharpen, and a sloppy registration face when you try to remove the burr by flipping back and forth, if you don't have a jig. I've been enjoying sharpening flat beveled tools lately.

Though, sometimes I do sharpen with an infinite number of microbevels! This when I sharpen with a convex bevel, which I also like - especially for thin plane irons and the like. I work the entire bevel, and don't find it to be that much extra work, really.

I keep the angle that I sharpen at fairly low with both methods, not exceeding 30 degrees.

If you're not working the entire bevel/erasing your microbevels each time, then you're just putting off a whole lot of grinding. If you are, you're still doing a good bit of grinding each time -- more so than you really need to in order to turn a burr at the edge, granted, you're doing it only on your coarse stone. I'm not convinced it's faster.

When you remove the jig, I really don't think micro-bevels are that great a way of sharpening. And requiring me to use a jig? Well, that's a fairly big deficiency right there, from my perspective.

[Don Dorn]

I don't normally read sharpening threads, not sure why I did with this one. I agree with most everyone who says that if they have a method that works, great. I'm not an avid follower of Rob Cosman but he did say something that resonated with me. He said that you should have a method that takes as little time as possible and gives good results because if it takes too long or too involved, you won't do it when it's needed and therefore, work with a dull tool.

For me, I adopted the Paul Sellers method and it works great for me and takes no more than a couple minutes (really) so I can use the tool as opposed to spending so much time sharpening. Find a quick way that appeals to you and keep with it.