How much sharper can you really get O1 or PM-V11 than A2?

[Christopher Wellington]

I'm pretty new to hand tools and I've been reading about the differences in the popular tool steels for plane blades - A2, O1, and PM-V11. What I've gathered is that A2 is harder than O1 but has larger grains. That means O1 can take a sharper edge than A2 but won't hold it as well. PM-V11 can also take a very sharp edge due to the small grain structure and wears very well, but at the cost of extra time grinding and polishing at the sharpening station. Seems like a pretty simple matter of determining how much I value sharpening time, edge retention, and ultimate sharpness off the stones relative to one another.

But I'm left wondering how much of a difference there really is, especially in ultimate sharpness. I recall a comment from a poster on another site who said he prefers O1 to PM-V11, but they're both better than A2 because, "you can actually get them sharp." Implying that you can't actually get A2 sharp. This is certainly a misleading statement, no?

So I'm curious, for the folks who have plenty of experience with these steels, how much of a difference do you really notice in how sharp your blades are straight off the stones? Is this the type of thing that gets grossly exaggerated in online discussions when in reality the difference is quite subtle? I'd like to sort of calibrate my expectations if I try some of these varieties.

For reference, I've used an old Stanley #4 and #5 for a couple of years, and more recently added a LN #5-1/2. I sharpen with 1000, 6000, and 16000 grit waterstones and the Veritas MKII honing guide.

[David Bassett]

... For reference, I've used an old Stanley #4 and #5 for a couple of years, and more recently added a LN #5-1/2. I sharpen with 1000, 6000, and 16000 grit waterstones and the Veritas MKII honing guide.

You can answer your own question. The Stanley irons are in the neighborhood of O1 and the L-N iron is as good as A2 gets. If they both work for you, you don't care. If you prefer one or the other, the only remaining question is if PM-V11 offers an improvement in the direction you'd like to go.

[Tom M King]

Can you tell any difference in the Stanley irons, and the LN 5-1/2 iron? There is some, but it's probably not something a person of average experience could tell, or if it would even matter.

I only have a couple of A2 irons, and no PM-V11 anything. I like 01 best, but I mainly work American woods. I only have those couple of LN specialized planes because they were cheaper than the old ones. They work fine for what I use them for.

[Christopher Wellington]

I can't tell any difference in any of the irons with the typical sharpness tests like cutting paper or running a fingernail along the edge. But I've never felt that those tests tell me much beyond "it's not dull."

When I actually use the planes, the LN performs dramatically better. It's a real pleasure where the Stanleys are usually a frustration. I think this may be related to other aspects of setup and probably my technique. The extra weight and longer sole length in front of the blade make the 5-1/2 easier for me to use. So that's not terribly conclusive either.

[John C Cox]

Realistically, sharp is sharp. The main hurdle when fancy pants high-carbide alloys hit the market was finding sharpening stones that could handle the carbides. This was an early problem that plagued 440c in knives too, and left a lot of people hating the stuff. Now, that's basically understood and it's not as much of a problem.

Be careful about broad brush alloy generalizations, especially from legacy web pages, as we're now a solid 20-years since A2 hit the mainstream, and the early issues were either worked out or the makers jettisoned it for other alloys that were better suited to their specific process. It's safe to say Lie Nielsen and Blue Spruce are making high quality tools out of A2, and people consistently like them. It seems like others, like Veritas and most of the discount import makers, have basically dropped A2 for other alloys.

[Barney Markunas]

A number of things factor into this including what kind of wood you work and what you use to sharpen your blades. Are you working softwoods, friendly domestic hardwoods, or tough stuff from Australia or elsewhere? Some sharpening media seem better suited to some steels.

My suggestion is spend the $60 to get a PM-V11 blade for one of your Stanleys and see what you think. I've had good luck with all of the steels you mention and how sharp they get probably has more to do with whether I am paying attention to what I am doing than it does with the steel that I am sharpening. I will confess that absolute sharpness is usually lower on my list of desires than sharp enough for a long time. I've not tried to quantify it, but my experience has been that PM-V11 gets plenty sharp enough, and more importantly to me, it stays acceptably sharp (a fuzzy notion I'll admit) longer than do the others.

[Scott Winners]

I own and have good things to say about all three steels. All three, at my shop, can leave a surface in ordinary wood smoother than I can get with 220 grit sandpaper.

My experience so far is overall feel of the tool in hand, balance, handle shape, that sort of thing is more important than which really good steel is at the edge.

[Robert Hazelwood]

Basically they can all get the same sharpness, if sharpened to the same geometry and with media that can cut the steel efficiently. Mostly, it's the last part that creates the reputation. O1 and other simple carbon steels sharpen beautifully on natural stones.

A2 has a little bit of chromium carbide which can be resistant to being cut by natural stones. O1 would only have iron carbides which are no problem for natural stones. I've been able to get serviceably sharp edges on A2 with Arkansas stones, however, so IMO this is somewhat over-rated. But if going for the Ultimate edge for this very finest of work, I think there is some truth.

But if you use something like aluminum oxide or silicon carbide (most synthetic waterstones, ceramic stones) or diamond paste, the carbides are no issue. Then its just a matter of getting the geometry right and to a sufficient level of polish.

One caveat is that you can take a simple carbon steel to a more acute edge angle without running into problems with chipping due to carbides. A more acute edge angle feels "sharper" and will perform better in soft materials. For the most part we are sharpening woodworking tools at 30 degrees or above, and about 30 degrees is on the borderline of being acute enough for this difference to become apparent. If you were sharpening knives for skiving leather at 15 degrees, or straight razors, you might easily conclude that A2 doesn't get as sharp.

My experience with A2 in a #4 bench plane is that it gets plenty sharp but instead of just gradually getting dull it inevitably develops little knicks that show up on the work, even though it can still take shavings (meaning the blade isn't that worn yet). I replaced the iron in my LN plane with a Hock O1 and prefer it, but it's not because it gets sharper in an absolute sense (thought it probably does get a little sharper if you are using natural stones).

[Edward Weber]

Realistically, sharp is sharp. The main hurdle when fancy pants high-carbide alloys hit the market was finding sharpening stones that could handle the carbides. This was an early problem that plagued 440c in knives too, and left a lot of people hating the stuff. Now, that's basically understood and it's not as much of a problem.

Be careful about broad brush alloy generalizations, especially from legacy web pages, as we're now a solid 20-years since A2 hit the mainstream, and the early issues were either worked out or the makers jettisoned it for other alloys that were better suited to their specific process. It's safe to say Lie Nielsen and Blue Spruce are making high quality tools out of A2, and people consistently like them. It seems like others, like Veritas and most of the discount import makers, have basically dropped A2 for other alloys.

I agree,
A2 is an air hardened steel but recently many have discovered that responds particularly well to cryo treatment, improving many of the characteristics we all look for in a steel for chisels and plane irons.
You need to know which one you have in order to compare, they are not al the same.

[Curt Putnam]

As compared to O1 and PM-V11, A2 suffers at angles <= 25°. It is not a question of sharpness, per se. When used in a bevel-down plane iron, there is no functional difference between the steels in terms of sharpness although there there may be in terns of edge durability.

[Christopher Wellington]

Interesting discussion so far. Thanks for the replies.

I've read that the cryo treatment improves toughness without reducing hardness in A2. I imagine that would help reduce chipping. Maybe I'll eventually buy one of the Hock irons in O1 for my 5 1/2 and swap between the two to compare.

The stones I'm using are a combo King KDS 1000/6000 and a Shapton glass 16,000 (HR). I think these are both synthetic stones and they seem to do a good job on the A2 steel. I use them to sharpen my chisels too. They're pre-Irwin Marples with blue handles, white ring and logo, and the blades say "Sheffield England". These seem to sharpen and hold an edge pretty well. Any idea what type of steel these might be made from? I'm just curious.

[Tom M King]

Those are by daily users too. I'm not sure what type of steel, but probably close to 01.

[Jason Buresh]

How are the results you are getting on actual workpieces?

While edge retention and tool steel make for great debates, none of that is important if you aren't getting good results on your workpieces.

I'm not trying to say you asked a bad question, I'm simply suggesting that the most important factor in tools is how they work the wood.

Tuning the plane, reading the grain, following the correct sequence of steps to prepare stock. All of these have a much more drastic effect on the finished piece. You could have the sharpest, most technologically advanced plane iron in the world, sharpened on stones mined from the peak of Mt Everest, stropped on giraffe leather with strop paste made from ground up unicorn horn using a robotic arm to maintain a perfect 25 degree bevel, but if it isn't set up properly or the board isn't flattened properly, that can all lead to tear out or tracks.

Just a thought.

[Christopher Wellington]

Jason - yes, I'm learning that good results with a hand plane depend on a number of factors. This is a persnickety tool.

Since picking up the Lie-Nielsen I've started getting what I consider very good results. When I have the blade sharp and adjusted well, read the grain correctly, use good technique, etc. I can get nice smooth surfaces on maple, cherry, etc.

[Warren Mickley]

I use English "cast steel" chisels from the 19th century. I like them because i can get a very fine long lasting edge. I use Arkansas stones.

I have tried the Lie Nielsen A2 chisels at tool fairs over a long period. Even when freshly sharpened they are noticeably inferior to the chisels I use. Maybe even worse when sharp than mine are when in need of sharpening. I believe the Lie Nielsen people have used Shapton, Ohishi, and one other type of stone to prepare the chisels over the years. If you look at the chisels with a hand lens they all have small chips, which may be due to beginners trying them.

What makes comparison hard is comparing different steel, different sharpening media, different techniques and different skill levels, all in one shot. Where in that jumble do you place the blame for a less than stellar edge?

In 2009 I took a small piece of wood to show and planed it with a Conrad Sauer A2 plane that had been freshly sharpened on 16,000 Shapton. The other side of the piece was planed by my 1915 plane iron. My side was smoother. Sauer no longer uses A2 irons.