Longer-lasting Sharpness?

[Patrick Chase]

I guess you guys probably do a lot more planing than I do though to worry about the metallurgic details.

Hah! Well played.

I worry about the metallurgic details because I'm an engineer and have some formal training in the field. It's well-practiced habit for me.

In Steve's case he makes planes and IIRC heat-treats his own blades, so he has legitimate reason to be very concerned with this stuff.

[Larry Frank]

I worry or think about the metallurgical details because to me it is interesting. I also enjoy reading some of the explanations that people come up with. There are some pretty good and accurate ones in this thread.

As a note, I spent many years making steel so this stuff is kind of part of me.

[Stewie Simpson]

Patrick; why is it; that you can get away with casting doubt on other forum members skills and technique; and yet provide no real evidence of your own skill level within woodwork; anyone can sit behind a computer desk, search the internet for answers, and claim them as based on my own experience. Theory based woodworking adds little to no practical value within a woodwork forum.

Stewie;

[Steve Voigt]

Hah! Well played.

I worry about the metallurgic details because I'm an engineer and have some formal training in the field. It's well-practiced habit for me.

In Steve's case he makes planes and IIRC heat-treats his own blades, so he has legitimate reason to be very concerned with this stuff.

Not that it matters, but just FYI I don't do the heat treating for 99% of the stuff that goes to market. I do heat treat the odd custom job, and a lot of tools that stay in-house (like floats that aren't commercially available, etc.). But yeah, if you are going to stuff made of tool steel, you should probably know the basics, which is all I know.

[Steve Voigt]

I worry or think about the metallurgical details because to me it is interesting.

Yep, that is the only explanation needed. If this board were restricted only to things that have practical value, there'd be a lot fewer posts. Which could be good or bad, depending on your point of view.

[Luke Dupont]

Very nice summary and explanation. I'll just add a couple nerdy bits for Luke et al about the low alloy stuff, which is what I have direct experience with (the higher-alloys not so much).

The steel used in a lot of late 19th c. – early 20th c. tools, particularly stuff marked "cast steel" as well as most laminated tools, is what's called "eutectic" steel, which means it has only as much carbon (about 0.7 - 0.8%) as can be eventually converted to martensite during heat treating. This means there's very few carbides in the final product, so such steel tends to be very fine-grained, takes an incredible edge, but doesn't have the wear resistance of steels with more carbides. A modern example of eutectic steel is 1075, which is approx. 0.75 % carbon.

On the other hand, steels like 1095 (0.95% carbon), ) O1 (1%), or Japanese white and blue (1.1 - 1.3%), are "hypereutectic" steels. They have more carbon than can be converted, so some of the excess carbon ends up as carbides, as Patrick explains, which is why these steels have greater wear resistance than eutectic steel. They are still very fine-grained, but not as fine as eutectic steel.

Then, as soon as you start adding stuff like chromium, manganese, etc., you start trading fine grain for wear resistance. This is barely noticeable in something like O1 but becomes more of an issue in steels like A2, and even more in something like D2, as previously mentioned in this thread.

Thanks for the explanation! That is a good write-up indeed.

The more I learn the more I'm thinking that I like simple steels, and being able to sharpen quickly and easily (and doing so more often) is more preferable for me than just having a steel with great edge retention.

Though, I have to say... I'm impressed even with the cheap laminated Japanese tools I own. The steel is easy to sharpen (lack of carbides, plus it's aided by hollows on the belly, and soft steel on the back/bevel), and yet holds an edge pretty well. I've also not had my edge fracture on me as I so often have happen with my A2 chisels when mortising. Lamination and careful design seems to offer the best of both worlds.

Does getting a tool to a sharper point, overall, help edge retention as well? I am noticing the benefits of having a fine finish stone to bridge the strop in terms of sharpness. Whereas I can get a very sharp edge just from a fairly coarse stone such as a Soft Arkansas or India, or 1200 grit diamond plate, I'm finding that I do in fact get a more refined level of sharpness by going to the Hard White Arkansas I have now first. Still not a super fine finish stone, perhaps, but the difference is noticeable for sure.

I might consider getting a finer stone yet, but if the Hard Ark proves to be good enough to follow up a fine India, I might just stick with it to keep my process really short and sweet with just two stones, rather than investing in a Black/Translucent/True Hard and requiring a third stone as a transition, or relying on a Soft Ark for working the bevel. But then, maybe I'll find I develop skill enough with the Soft Ark to use it that way.

I am really liking the Hard Ark, to my surprise, whereas the Soft Ark is just kind of so-so for me. I expected it to be the other way around.

As it kind of relates to this: Part of the reason I went with Dan's for my Arkansas stones is due to a recommendation by Christopher Swartz, who noted that his Arkansas stones from Dan's do well with A2. I haven't quite found that to be the case with my Narex chisels that I keep bringing up; I *can* sharpen them, but nowhere near as easily as my Japanese tools and O-1 plane irons and gouge. I assume this difference in experience might be explained by the varying properties/quality of A2 involved that someone brought up, if not variance in the stones as well.

The only question I have is... If my steel is harder than my stone, could I run the risk of say, burnishing my soft arkansas to a finer surface finish thereby reducing its cutting speed by using hard A2 on it?

[Patrick Chase]

A few comments...

Though, I have to say... I'm impressed even with the cheap laminated Japanese tools I own. The steel is easy to sharpen (lack of carbides, plus it's aided by hollows on the belly, and soft steel on the back/bevel), and yet holds an edge pretty well. I've also not had my edge fracture on me as I so often have happen with my A2 chisels when mortising. Lamination and careful design seems to offer the best of both worlds.

A2 is very abrasion resistant, but it's prone to fracture/chipping for reasons that have already been covered. You need a very high tip angle (35 deg or so) to avoid chipping when mortising with a chisel like that. You won't want to grind the entire bevel at such a high angle, though, just the tip.

Does getting a tool to a sharper point, overall, help edge retention as well? I am noticing the benefits of having a fine finish stone to bridge the strop in terms of sharpness. Whereas I can get a very sharp edge just from a fairly coarse stone such as a Soft Arkansas or India, or 1200 grit diamond plate, I'm finding that I do in fact get a more refined level of sharpness by going to the Hard White Arkansas I have now first. Still not a super fine finish stone, perhaps, but the difference is noticeable for sure.

Yes, sharper edges do last longer, but they should be uniformly sharp. When you have a chip or notch the cutting forces are higher at that location, and those higher forces translate into faster wear all else equal.

As it kind of relates to this: Part of the reason I went with Dan's for my Arkansas stones is due to a recommendation by Christopher Swartz, who noted that his Arkansas stones from Dan's do well with A2. I haven't quite found that to be the case with my Narex chisels that I keep bringing up; I *can* sharpen them, but nowhere near as easily as my Japanese tools and O-1 plane irons and gouge. I assume this difference in experience might be explained by the varying properties/quality of A2 involved that someone brought up, if not variance in the stones as well.

Narex tools aren't A2 - they use their own uniquely-processed "Cr-Mn" alloy. I don't know the composition, but from experience with my own Narex tools it behaves somewhere between O1/HCS and A2.

In any case, I remember reading that article at the time and sort of shaking my head. Like JNats, Arks are made of a form of SiOx (Novaculite), and SiOx is inherently problematic on steels like A2. That's simple physics, and it doesn't matter what brand the stone is. Whether it "does well" probably depends a lot on your definition of "well".

[Brian Holcombe]

In attempt to continue pushing my personal boundaries forward, i find threads like this to be interesting. Some of the rabbit holes that we can fall down do produce insightful commentary which can be found useful.

[Jim Koepke]

Does getting a tool to a sharper point, overall, help edge retention as well?

Aside from what others have said, my thought is every time an edge cuts into something there is a bit of wear to the blade. It may be minuscule or on the level of atoms, yet it is still wear. If the amount of wear is equal per stroke, not likely, then the sharper blade will cut longer before getting to the point of needing a trip to the stones. As Patrick mentions there may actually be more wear to a point along an edge that is less than sharp. With this in mind an edge of lesser sharpness will have a faster wear profile.

I might consider getting a finer stone yet, but if the Hard Ark proves to be good enough to follow up a fine India, I might just stick with it to keep my process really short and sweet with just two stones, rather than investing in a Black/Translucent/True Hard and requiring a third stone as a transition, or relying on a Soft Ark for working the bevel.

A comment like this makes me wonder what advantage there may be of a 'two stone solution' over 'hair splitting sharpness.'

When possible my blades are honed on just two stones. More often than not it takes three water stones (1000, 4000 & 8000) or four or five oilstones (soft Ark/Washita or India stone, hard Ark, translucent Ark, super hard trans Ark and a piece of Jasper). The last two have less cutting action and more of a burnishing effect. Depending on my mood at the time they may then be stropped.

In my experience a few quick rubs on a coarse stone will make the overall honing session quicker than if the work is started on a smoother stone.

jtk

[Steve Voigt]

Luke,
To piggyback off of what Jim K said, all you really need is 2 stones. The usual combo is medium or fine India + translucent or hard black Ark, but a regular hard Ark should give you a serviceable edge. If you want sharper than the hard Ark can give you, the easy, single-digit $ solution is some green chrom ox paste on a block of mdf or hardwood, whatever you've got. You can use this just like a stone (with the caveat that you should be careful about pushing forward, so you don't dig into the wood or mdf and chew it up), and it will give you a very fine edge.

Returning to the topic of the thread ("longer-lasting sharpness), if you are using oil stones, the number one thing that will shorten edge life is failing to remove all traces of burr. If you are finishing with a hard Ark, you almost certainly will have remnants of the burr that need to be stropped off. A traditional, untreated leather strop would be best for this. If you go the green paste + mdf route, there will be very little burr left, but I would still do some palm stropping to make sure.

[Luke Dupont]

> Jim

Well, I do prefer to keep the process as simple as possible sometimes. I don't have a proper shop, really, so I have to get all of my tools, stones, and what have you out each time I work, and I often go places to work, so keeping things minimal can be quite nice.
If I had a dedicated shop with a sharpening station where I could just leave my stones ready to go, I wouldn't worry about it.

If I'm looking for hair splitting sharpness though, as when I'm planing tough grain or paring endgrain, or if I just feel like it, then I will go that extra bit. I just like to know my options.


> Steve

Do you mean that jumping from a fine india to a translucent/black arkansas would actually work fine?

I do have a leather strop that I use for just that purpose of removing the bur and final polishing after the stone. I do have a hard time removing the burr completely on the stone, even flipping back and forth with light strokes, and I thought that was just due to lack of skill. I guess people who finish on stones alone are just using very fine stones that aren't aggressive enough to turn a significant burr?

Stropping off of the hard ark does give me as sharp an edge as I've experienced, but then, it's still the finest stone that I've used with the possible exception of a 2400 grit waterstone, to which it seems pretty comparable.

I'm surprised that you recommend an untreated strop, though. I've always used green chromium oxide on my leather strops. You find that leather alone will suffice (or does better in this capacity, even)?

[Luke Dupont]

In attempt to continue pushing my personal boundaries forward, i find threads like this to be interesting. Some of the rabbit holes that we can fall down do produce insightful commentary which can be found useful.

Haha, yep! I learn a lot from these sort of threads as well. I've been going back and reading your thread on Jnats as it's sort of related, and there's a lot of interesting information there as well.

Sometimes I make a special effort to fall down rabbit holes. It can be a good way to learn.

[Patrick Chase]

Do you mean that jumping from a fine india to a translucent/black arkansas would actually work fine?

This is going to be an over-simplification, but: In a properly executed sharpening sequence your last stone is the one that determines the quality of the edge, period. In such a sequence each stone removes all scratches left by the previous one[s], so that the only scratches left after the last stone are the ones it added.

With that in mind, just about *any* system can "work fine" as long as the last stone is up to the job. The catch is that if you make too big of a jump then productivity will suffer as you'll end up spending forever with the last stone to get rid of the previous stone's scratches. It's therefore a tradeoff between cost, honing time, and hassle.

Stone whores like me tend to shoot for 2-3X jumps from one stone to the next, for example my Sigma Power waterstone set goes 1K-2K-6K-13K. With those sorts of steps you don't have to do much work at all on each successive stone, since the scratch pattern from the prevous one isn't that much bigger.

People who prefer to minimize their equiment use bigger jumps (1200 Bester-8K Imanishi for example) all the time and get great results as well, though they probably spend more time doing it.

[Brian Holcombe]

Haha, yep! I learn a lot from these sort of threads as well. I've been going back and reading your thread on Jnats as it's sort of related, and there's a lot of interesting information there as well.

Sometimes I make a special effort to fall down rabbit holes. It can be a good way to learn.

Each subject that you become experienced in helps push you forward, in my opinion. I've entered a planing competition and so it to requires consideration of things I do not 'need' in my woodworking but can actually help at some point. Pushing myself to understand what's happening at the edge and ahead of the edge to a much higher degree can prove insightful ultimately leading to a better overall ability.

Glad you are enjoying the Jnats thread!

[Mike Holbrook]

Good points Brian. Sometimes going to extremes helps us to exceed expectations at normal levels of typical activities. Good luck at the competition, you don't even need to worry about WINNING!