My take on sharpening

[Martin Loesing]

Hello everyone,
I'm new to SMC so first of all I would like to thank everyone who contributes to this forum for sharing their knowledge.

There are obviously many ways to successfully sharpen edge tools and I'm not claiming to hold any ultimate truth. So this post is simply meant as some input to those who struggle with sharpening or those who like to experiment.

A few month ago I've discovered the blog https://scienceofsharp.wordpress.com/ where (mainly) straight razors honed on different media are examined via electron microscopy. One of the conclusions of the resulting images is that edge trailing strokes on sharpening stones create a keen, chip free edge but also a burr which is quite difficult to remove and which when ripped off leaves a rough/heterogeneous edge apex. Edge leading strokes on the other hand create a micro-chipped but burr free edge, with the size of the micro-chips being correlated to the coarseness of the sharpening medium.

Based on these conclusions I've adapted my sharpening technique and now do only edge-leading strokes on my sharpening stones (which is facilitated by using a honing guide where you can lift the edge on the return stroke). After honing on my final stone I do very few (still experimenting here, but around 5) edge- trailing strokes on the same stone to refine the keenness of the edge without creating a burr.

I get great results using a two stone setup consisting of a worn in EZE-LAP 1200 and a Shapton 6k, with finer stones being completely unnecessary I think. A note of caution this technique seems to work quite quickly and with a low stroke count but will not polish the bevel very well. I've only tested this on simple carbon steels, so it might be different for more tenacious steels.

Kind regards,
Martin

[Mike Cherry]

Welcome to the creek Martin! Interesting thoughts on edge leading strokes. I have always trailed the edge but true sharpness was never realized until I made very sure to remove the wire edge completely. I do this with a strop. There's a couple or three ways to get to sharp, I'm glad you found yours!

[Phil Mueller]

Martin, welcome to SMC! Thank you for posting your sharpening technique. I think you'll find a zillion opinions on sharpening, but it comes with a great appreciation for everyone's trials and successes. I have believed in the past, there is a bit of over obsession in sharpening, relying on sandpaper and plate glass myself. But i must admit recent projects requiring a lot of end grain paring has highlighted some shortcomings in my sharpening technique.
All input is helpful in our quest for sharp.

[Jim Koepke]

Howdy Martin and welcome to the Creek.

I am always curious to the spot on earth others call home. Where is your home spot?

There is more ways to sharpen than most of us care to imagine. Some strong opinions can be found in most discussions about sharpening.

My sharpening used to stop at a 4,000 stone. It did pretty good. Then along came an 8,000 stone and things were a bit better.

I know a bit more sharpness and a higher polish could be coaxed onto my blades with a finer stone, but it seems to be a diminishing return compared to the added cost.

jtk

[Frederick Skelly]

Welcome Martin! Glad you've joined us. Thanks for the input on technique - I plan to give that a try and see if it works better for me.

Fred

[Brian Holcombe]

Martin, do you inspect your work with a microscope? Curious if your findings follow closely to those linked. The chisel edge is a few degrees steeper than a straight razor, which I wonder if it minimizes the effect of trailing strokes.

[Tom M King]

I sharpened on oil stones for at least the first 20 years, and only ever went forward. No reason other than that's the way I taught myself to do it. It works just fine. It's still ingrained in my wrists, and I have no reason to do otherwise, except on the diamond lapping film I use to finish with. It's easy to slice that film with a sharp iron going forward, and I haven't used any yet that I haven't sliced by thinking about something else while doing it. Fortunately, it still works just fine with a slice in it, but you should only go backwards on that stuff.

[Warren Mickley]

Martin, do you inspect your work with a microscope? Curious if your findings follow closely to those linked. The chisel edge is a few degrees steeper than a straight razor, which I wonder if it minimizes the effect of trailing strokes.

My razor is 17 degrees (8 1/2 on each side) my chisels are 30 degrees. There are some differences in technique sharpening the two.

[Brian Holcombe]

I'm playing devil's advocate a bit, but I tend to bias all of the work to the bevel edge on my chisels, but flip the razor every stroke.

[Derek Cohen]

A few month ago I've discovered the blog https://scienceofsharp.wordpress.com/ where (mainly) straight razors honed on different media are examined via electron microscopy. One of the conclusions of the resulting images is that edge trailing strokes on sharpening stones create a keen, chip free edge but also a burr which is quite difficult to remove and which when ripped off leaves a rough/heterogeneous edge apex. Edge leading strokes on the other hand create a micro-chipped but burr free edge, with the size of the micro-chips being correlated to the coarseness of the sharpening medium.

Hi Martin

Welcome to the forum!

That is an interesting observation and, intuitively, it makes sense.

My preference is side-to-side sharpening, and I recall reading an article (by Harrelson Stanley) that claimed it created less "chipping" at the edge and, thus, a stronger edge.

However there are occasions when other directions are used owing to circumstances. For example, I would hone a 1/8" chisel on a hollow and drag it back over the waterstone - since pushing it forward might gouge the stone. Similarly, high angle (50 degree) micro secondary bevels for BU plane blades are best done using a honing guide. At that angle, one is forced to drag the blade. It would also gouge the stone if pushed forward.

Regards from Perth

Derek

[Pat Barry]

I've also seen, and tried, a figure eight technique that gives you the best of both worlds. In the end, its really whatever works best for you isn't it?

[Nicholas Lawrence]

Well, now we have some competition for the imperial versus metric thread....I'm not sure this will make 9 pages though.

[Mike Cherry]

Well, now we have some competition for the imperial versus metric thread....I'm not sure this will make 9 pages though.
Hehe yea this is definitely one of those topics that can go on for days!

[Brian Holcombe]

Practicality weighs in as well. I'm working on those long handles Tsuki's and I dont remove the handles to sharpen (some people do on carpentry slicks and such). To maintain the bevel by hand I generally make short strokes with the blade on a diagonal so that I have the longest possible reference surface in the direction I'm pushing the chisel.

Shorter handles make the work a little easier and I can get closer to side-to-side sharpening.

[Ian Moone]

Plasma sharpening!

https://www.youtube.com/watch?v=PNq4Oa1GwwE

I thought everyone already used this? ;)

[David Eisenhauer]

Hello and a very welcome to the forum. I must ask, though, that you exercise some caution when posting, because, as you see, it is so very easy to set free the dogs of sharpening. Perhaps you could start with something slightly less soul stirring, such as the great LN vs LV, or the aforementioned Imperial vs Metric subjects?

[Kees Heiden]

Yes that was a couragous act!

Personally I like the burr when sharpening. It tells me when I have really reached the edge all the way across the tool. Removing the burr isn't so difficult on a finer stone and a strop. And I like going backwards and forwards, or in circles, beacuse it is quicker then making a stroke, lifting up the tool, set it back at the start of the stone and repeat.

But that's just me. If it works for you, fine.

[Robert Hazelwood]

I like to work back and forth on the coarser grit stones while I establish a new edge. That is to save time. I try not to over-sharpen which would create a large burr on a coarse stone. Before I finish with each grit, I will make a series of forward-only strokes, alternating sides, to help get rid of any burr before moving on to the next stone. On the final polishing stone I will finish with the alternating forward-only strokes, then raise the angle slightly (judged by eye, but perhaps around 1 or 2 degrees) and take a few very light passes, forward only, alternating bevel and back. I typically do not strop.

Aside from stroke direction, pressure is another factor that affects burr formation. The final strokes should have very little pressure; in fact I try to think of just barely lifting the weight of the blade while still allowing it to touch. Raising the angle slightly on the last few strokes of the polishing stone is also very effective at removing any burr.

Also, I often begin the sharpening by intentionally dulling the blade. I do this by dragging the blade at a 90 degree angle on a medium stone for one or two strokes. This is to remove fatigued metal from the existing edge, so that none of the weakened metal remains in the new edge I'm creating. It creates a very small flat on the edge which reflects light. As I shape the edge I periodically check this flat to see how close I am to removing it. Ideally I can sneak up on this and avoid creating any noticeable burr (i.e. my last sharpening stroke removes the very last remnant of the flat).

Credit for many of these ideas goes to Cliff Stamp, who has a good website and forum discussing sharpening, metallurgy, etc. It's oriented towards knives primarily, but sharpening concepts are pretty universal.

[Derek Cohen]

Also, I often begin the sharpening by intentionally dulling the blade. I do this by dragging the blade at a 90 degree angle on a medium stone for one or two strokes. This is to remove fatigued metal from the existing edge, so that none of the weakened metal remains in the new edge I'm creating.

This is good, Robert. Several years ago, in correspondence, Harrison Stanley related to me what he called his "jointing technique", which was the lightly run the blade edge on a fine-ish stone to straighten the edge and remove any micro chips.

Regards from Perth

Derek

[Andrew Hughes]

I didn't think anyone knew about jointing the edge.So I never even botherd to bring it up.I remember reading about it in a book before I saw Harrelson Stanley demo it at a show out here in Calif.
I use it once in awhile.Every little bit helps esp with A2 steel.

[Allan Speers]

I've also seen, and tried, a figure eight technique that gives you the best of both worlds. In the end, its really whatever works best for you isn't it?



Figure 8 here as well, except when I need to use the jig to re-establish a bevel. It seems to work as well as side-to-side, but faster.

[ken hatch]

I'm not sure the pattern you use makes a hill of beans to the final edge be it back and forth, side to side, figure 8, push, pull, or all at the same time. What I think does matter is the feel of the iron on the stone, if you can't feel the interaction between the iron and stone it is very hard to make the small changes to pressure and motion to achieve your best edge. BTW, I use most of the patterns as needed.

The reasons I prefer a natural stones for finishing is the "feel" and I think they produce a better working edge vs. synthetic. I know, it could be the magic stone syndrome and I expect there are some synthetic stones that in a "blind" test would give a natural stone feedback but either through bias or just not trying enough I haven't found one.

ken

[Mike Cherry]

I'm not sure the pattern you use makes a hill of beans to the final edge be it back and forth, side to side, figure 8, push, pull, or all at the same time. What I think does matter is the feel of the iron on the stone, if you can't feel the interaction between the iron and stone it is very hard to make the small changes to pressure and motion to achieve your best edge. BTW, I use most of the patterns as needed.

The reasons I prefer a natural stones for finishing is the "feel" and I think they produce a better working edge vs. synthetic. I know, it could be the magic stone syndrome and I expect there are some synthetic stones that in a "blind" test would give a natural stone feedback but either through bias or just not trying enough I haven't found one.

ken
Ken,
I agree that pattern doesn't produce a difference, at least not in my edges. I use various methods too. For example, the narrower blades I usually only pull the blade towards me. On scrub blades I roll the blade, alternating from left to right then right to left while pulling towards my body. Like you, I find the end result has more to do with the feedback I get from the steel on the stone.

[ken hatch]

Ken,
I agree that pattern doesn't produce a difference, at least not in my edges. I use various methods too. For example, the narrower blades I usually only pull the blade towards me. On scrub blades I roll the blade, alternating from left to right then right to left while pulling towards my body. Like you, I find the end result has more to do with the feedback I get from the steel on the stone.

Mike,

The link was an interesting read and has some good information but, as always there is that damn "but".....From a working wood perspective what matters to me is a "working" sharp edge. All edges except one too dull to work will degrade at the first touch of wood anyway. What I'm interested in is the balance between sharp enough and working sharp long enough to do the job at hand. Many times a strop, even if it slightly dubs the edge, will help achieve that balance.

I guess the bottom line is, who cares how someone gets there....Folks just need to find a way that fits in their work flow and gives a good sharp tool. Then go make furniture.

But while taking a break for coffee or tea it sure is fun to read about, I'd guess mostly because it brings everyone out and posting.

ken

[Mike Cherry]

The silver lining is that we're all talking about free handing which is, I feel, good to see people doing. There's freedom in free handing!

[Ian Moone]

I find it too tough to hold the plasma handle steady on a constant angle free-handing and prefer to employ a jig to keep it constant!. :D

[Martin Loesing]

Thanks for the replies, I appreciate them :)


I was always a bit frustrated by the back and forth motions or circles most people do as I never got a good degree of consistency. A burr would form, which sometimes would be hard to get rid of, requiring switching from the bevel side to the flat side frequently. This is extremely cumbersome when using a honing guide. I'm getting better at freehand sharpening but could feel that I unintentionally convex some of my irons, especially if they are thinner. Now I can work on the bevel side most of the time and will only do a few edge-trailing strokes on the flat side at the end of the honing progression, so I'm a lot faster.

Stropping is an interesting alternative, as is also shown on the science of sharp blog, it micro convexes the edge apex and removes the first few microns of the edge and thus possibly any burr. It may be interesting to do only edge-trailing strokes prior to stropping to create a very keen, linear edge, possibly only on a coarse stones as well. On the blog there is one interesting example of a razor honed on a 320 Shapton with edge-trailing strokes, which exhibits a perfect edge under a massive burr. My experiences with stropping were varied but in the end not very consistent as well, but that is probably down to my inability to keep a consistent angle on a leather strop.

@Brian: I have been thinking about getting a microscope but am still undecided. It might be quite useful to see if there are any (large) chips in the edge but other than that I think the resolution may be insufficient, especially as scratches on a bevel do not necessarily have any impact on the edge itself as shown by the electron microscopy.
As for the bevel angle, well I can't really think of a reason why it should impact the sharpening a lot. Do you have any theory here?

@Derek: Side sharpening is a very interesting concept, as such a motion should only yield a burr perpendicular to the edge, making it probably the most efficient way. However I find holding a chisel or plane blade for true side sharpening quite awkward and usually resort to a diagonal movement when free hand sharpening. I might give the sharp skate a try in the future.

Kind regards,
Martin

[Robert Engel]

Marty -

Sharpening (like dovetails) is one of those ww'ing subject IMO many people get so anal about but is so simple.

I don't think sharpening a straight razor is the same as a single bevel chisel or plane iron, so I don't think you should alter your sharpening technique.

Second, I don't understand why a honing guide gets in the way of removing the burr. It should be far enough back from the bevel edge to allow you to remove the burr quite easily. A burr isn't hard to get rid of. Literally one swipe on a 4-8K grit stone and you're done.

The bevel angle definitely affects sharpening to the extent that the lower the angle the shorter the edge retention because there isn't as much metal backing up the edge. IOW you will be doing it more frequently. That being said, I keep a couple low angle chisels for soft wood it kind of evens out the edge retention equation.

I think the best policy on sharpening is adhere to the basics then find what works for you and don't change it for nuances like this.

Don't get a microsope. Don't sweat the small stuff.

[Brian Holcombe]

I enjoy a little overindulging in sharpening discussions and I've made those sort of 'ahh-ha!' moments that have simplified my process greatly from extensive rhetoric.

So all of this exhaustive discussion has resulted in improving a process from what used to take me forever to achieve poor results to what takes me little time at all to get great results.

Marty, my thought is that a higher bevel angle makes a less substantial burr.

[Pat Barry]

That perfect edge you seek is going to last approx 1 stroke =>/ Don't overthink this so much. You don't need a microscope to get a sharp tool and a bit of a burr is not a sign of failure