A2 steel plane blades

[Jim Paulson]

Hi creekers,

I've got a 605 bedrock plane that I'm restoring to use with a shooting board. The plane cleaned up real nice and the only thing I'm changing on it is to add a replacement blade and maybe a new chip breaker. I want to beef up the iron thickness with a Hock blane. What do guys recommend on the blade steel? My preference has always been to get my cutting edges razor sharp, can I get that with A2 steel or should I stick with my gut and go with O1 steel?

Jim

http://www.chairsbypaulson.com

[Casey Gooding]

Either will take a nice edge. Some people think that O1 takes a keener edge. However, if you are using it for a shooting plane, then A2 might hold an edge better against end grain than O1 would.

[george wilson]

A2 is better for wear resistance. I use it on all of the dies and punches for our home business. they punch thousands of pieces of paper and lexan before needing grinding. Paper is abrasive.

[Derek Cohen]

I think that the reason that O1 is considered to take a better edge than A2 is caused by improper sharpening technique. As I understand, the grain structure of O1 and A2 is very similar. It is the extra abrasive-resistance of A2 that can cause some people a problem. If you are honing full faces of a thick A2 blade, then I expect sharpening (especially with oilstones) to be harder going. However I doubt that you would notice any difference if working with microbevels (via a hollow grind or a flat primary bevel). I do not find any difference in "sharpness" with the two types of steel. I use Shaptons.

Regards from Perth

Derek

[Larry Williams]

Hi creekers,

I've got a 605 bedrock plane that I'm restoring to use with a shooting board. The plane cleaned up real nice and the only thing I'm changing on it is to add a replacement blade and maybe a new chip breaker. I want to beef up the iron thickness with a Hock blane. What do guys recommend on the blade steel? My preference has always been to get my cutting edges razor sharp, can I get that with A2 steel or should I stick with my gut and go with O1 steel?


I would suggest staying with O-1. Reports of longer edge life for A-2 are subjective and I can't verify any significant difference. Yes, A-2 does have a higher resistance to abrasive wear. If you're dealing with a wood with a high silica content or something then you may benefit from the higher abrasive wear characteristics of A-2. Most wear to a woodworking edge tool, though, is the result adhesive wear and O-1 and A-2 have virtually identical properties when it comes to adhesive wear resistance. However, A-2's resistance to abrasive wear makes it more difficult to hone and grind.

O-1 has a higher resistance to chipping than A-2. To deal with this most manufacturers suggest more obtuse bevel angles for A-2. The reason manufacturers prefer A-2 is that it has a better dimensional stability in heat treating so it requires less work after heat treating. A-2 is also better suited for mass production because it doesn't require an oil quench but quenches in air.

One of the givens in heat treating is that the higher the heat treating temperature and the more time at that temperature, the more coarse the grain of the steel will be. A-2 requires a higher temperature than O-1 and a longer soak at that temperature.

Here's a chart from Bohler Uddeholm that shows the properties of the steels:

http://www.planemaker.com/photos/A2vsO1.jpg

This chart comes from Uddeholm's web site and a .pdf document about O-1 at:
http://www.bucorp.com/files/aisi_o1.pdf

There is a similar .pdf document for A-2 at:
http://www.bucorp.com/files/aisi_a2.pdf

There is a short but reasonably good definition of adhesive wear at:
http://www.surfaceengineering.com/Solutions-Adhesive.htm

I think if you avoid all the subjective stuff and the thaumaturgic nonsense out there you'll find O-1 offers better properties, good performance at traditional bevel angles and is a lot easier to maintain. There are a number of reasons I avoid A-2 but these are the main reasons.

[george wilson]

Of course A2 is going to be harder to sharpen. There is no free lunch. It holds an edge longer,but is also harder to sharpen.

I don't understand your logic,Larry. You admit that A2 is more resistant to wear,and your chart verifies it. Yet,you say there is no difference?

Having been a toolmaker for many years,I much prefer A2. I use a diamond stone to sharpen,and then black,then white ceramic stones.Last,a strop. If you use these very hard diamond and ceramic stones,A2 is not a lot of work to sharpen. The stones just need to be hard enough to efficiently sharpen the chromium bearing A2 steel.

D2 is very considerably harder wearing,and these stones are the ones you must use to bring up a razor edge. Years ago I made my first D2 knife,and I could not quite get it to a true razor edge because my stones were too soft. When I switched to my present stones I had no trouble getting a razor edge.

[Jim Paulson]

Thanks guys,

Perhaps part of my reluctance to embrace A2 has stemmed from a need now to purchase more sharpening stones. Shaptons as Derek and others are pointing out permits A2 to get the necessary sharpness. Scanning the previous posts, one would need at least 1, 2 and 8K Shapton stones. Would that work well with me currently using my worksharp initially then going to the 1K stone?

See this is where I'm at, O1 is easier with my current setup. Larry, I appreciated your input here. With my worksharp I've got the option to do the scary sharp deal or use my DMT stones or waterstones to get the job done. But you all are helpful here in considering the jump to A2. Embracing A2 for me means buying some new stones, but the benefit is that the blade gets longer edge life.

Jim

[Stephen Reid]

A2 can be sharpened just as easily with scary sharp as O1.I go from the grinder to 400 1000 2000 then hone on green compound. No problem getting razor sharp.I have both types of irons from LV

[Derek Cohen]

Jim

I don't wish to imply that you need Shaptons to sharpen A2 steel. In fact I believe that you could even do so with oilstones (which I have nil experience with) as long as you use microbevels in your strategy.

If you freehand, simply use a hollow grind. If you use a flat bevel, simply add a micro secondary bevel.

If you were thinking of Shaptons (great stones but not essential), then you can get away with just a 1000 and a 8000. But there are other options that work - sandpaper, diamond (stones and paste) and other waterstones (e.g. Norton - I have not tried A2 on Kings. Keep in mind that LN sell a lot of A2 steel and also sell Norton waterstones ... makes you think?!)

Regards from Perth

Derek

[Larry Williams]

George,

There are two kinds of wear. The dulling wear on a woodworking cutting edge is most often the result adhesive wear, where molecules from one surface are transferred to the contacting surface. Abrasion wear is where cutting edges, usually quite small are cutting away chunks of steel that may also be quite small, but not at the molecular level.

A good example of this is bronze which has a low abrasion wear resistance but a high adhesive wear resistance. That's why bronze is used for bearings instead of A-2.

Look at your dull cutting edges under magnification. Do you see signatures of abrasive cutting and the resulting dull/flat appearance? No, you'll see a highly polished and rounded from wear at a molecular level. You can't see the iron/carbon/alloy molecules on your shavings but they're there and they're there through adhesion rather than abrasion.

Go to your metal working shop, George, and look at all the coatings that have been developed for metal working tooling. That's what those coatings do, they resist adhesive wear that dulls the tooling. The same thing is showing up in woodworking tooling as more and more indexable tooling is showing up. These coatings don't make sense for tools that are intended to be sharpened but things are moving toward indexable tooling for power woodworking tools. Those coatings are actually more prone to abrasive wear than the tooling they coat but they're effective at resisting the adhesive wear that shortens tool life. You do have to know the properties of the coatings and adjust feeds and speeds accordingly to get maximum benefit.

Go back and look at the chart I posted. There's a reason there's a column labeled "adhesive wear." It's an important column. Go look at the definition of adhesive wear I posted a link to. There are good reasons engineers look at adhesive wear.

One way to increase adhesive wear is to increase the pressure between the two involved surfaces. One of the results of the more obtuse bevel angles suggested for A-2 is increasing the pressure between the two surfaces. Can you say, "faster wear?"

If you happen to be working a wood like bois d'arc or Western cedar with a high silica content, you might see some advantage in A-2. However, Western cedar is incredibly soft wood and really needs acute bevel angles to successfully work it. Western cedar may be the single most difficult wood I've worked with hand tools. It requires very sharp tools, acute bevel angles and the knots are probably the hardest wood I know of. The knots in Western cedar will chip a cutting edge in a heart-beat. Even with its high silica content, I wouldn't suggest A-2 steel because of its propensity to chip and the obtuse bevel angles required to deal with that chipping.

[John Coloccia]

Much of the loss of sharpness with wood tools is deformation of the edge, not necessarily abrasion. A2 is typically hardened to 60+. O1 a bit less. Hardness determines the resistance to edge deformation. Once the edge deforms, the forces on the edge go up and things go from bad to worse in a jiffy.

Nearly every piece of steel in my shop is A2, except my Japanese chisels and they're even harder. I sharpen everything on normal, everyday Norton water stones. Nothing exotic. I've also used scary sharp, and I use a Tormek as well. I hardly ever grind anymore, by the way. As soon as a cutting edge is no longer "I can shave with it" sharp, I strop it for a couple of seconds, and it comes right back. It's way easier to maintain an edge sharp than it is to sharpen.

As far as which gets sharper, there's nothing in my shop that gets sharper than my Japanese chisels. I can literally split hairs with those. I can't tell the difference between A2 or O1. Both get sharp enough to shave. The A2 certainly does last longer between honings and I don't think that has anything to do with wear. My personal belief is that the predominant dulling mechanism is plastic deformation of the edge, rapidly followed by microscopic chipping of the edge.

[george wilson]

Thanks,Larry, like I really need a lecture on tool steel.:)

John,you say that you can't tell the difference between A2 and 01,and then say that the A2 certainly does last longer between sharpenings!

O1 is a simpler steel than A2. A2 contains more chrome.O1 doesn't have much.

O1 contains up to .95 carbon, only up to .60 chrome, up to .20 vanadium,and up to .60 tungsten. These,except for the carbon,are pretty low alloy figures. A2 has up to 1.05 carbon,up to 5.30% chrome,and up to 1.10 molybdenum,and like 01,up to .20 vanadium. I'm leaving out the stuff like silicon,sulfur,etc.

Because of the great increase in these added metals,A2 is a much superior metal. It becomes air hardening due to the added alloys. Years ago,I used 01 for most everything because I didn't have the necessary furnace to harden A2. Now that I have everything I need to use the better metal,I use it for most everything that has to hold an edge.

I make the tooling for our jewelry making business. We use a lot of punches and dies,which are a lot of trouble to make,and which I want to continue to be useful for many years should I die. I am 19 years older than my wife. We punch many thousands of paper and Lexan parts between sharpenings. I don't have to re grind the punches even 1 time every 2 years.

The only other metal I would use is D2,but it is a bear to machine,with about 12% chrome.

Another advantage of A2 is that it is nearly distortion free,being an air hardening steel. My punches and dies must fit VERY perfectly together to cut thin pieces of paper like a pair of scissors. Any gap at all and the paper tears and leaves a ragged tail.

I think the fact that LN and LV have gone to A2 should be an excellent recommendation of its superiority. I encouraged LN to use it years ago when they were using O1. By the way,LN told me that they only hardened the LAST INCH of their plane blades because of warping problems!!!

As for A2 being easier to manufacture with,it is MORE complicated to manufacture with,because you have to have an oxygen free furnace,or wrap it in stainless steel foil. Advantages are it warps less,and holes drilled in it before hardening don't so easily crack through in the (air) quench. 01 needs holes packed full of steel wool to keep them from possibly cracking. Depends upon what you are making in the end.

[Jim Koepke]

Thanks guys,

Perhaps part of my reluctance to embrace A2 has stemmed from a need now to purchase more sharpening stones. Shaptons as Derek and others are pointing out permits A2 to get the necessary sharpness. Scanning the previous posts, one would need at least 1, 2 and 8K Shapton stones. Would that work well with me currently using my worksharp initially then going to the 1K stone?

See this is where I'm at, O1 is easier with my current setup. Larry, I appreciated your input here. With my worksharp I've got the option to do the scary sharp deal or use my DMT stones or waterstones to get the job done. But you all are helpful here in considering the jump to A2. Embracing A2 for me means buying some new stones, but the benefit is that the blade gets longer edge life.

Jim

Jim,

I use a Veritas Mk.II Power Sharpening System with abrasive disks similar to the Worksharp. From the published information on the Worksharp abrasives it looks like the finest Worksharp abrasives are finer than the 1K and 2K stones. With the Mk.II I go straight to a 4K then an 8K stone after using the finest abrasive disk. Let the electrons do the hard part, then the rest can be done quickly by hand.

As others have said, in the long run you will do less work if you hone a blade before it gets dull enough to be unusable.

I think the only way your question will be answered is not with the great information others have posted. Your answer will have to be formed from your using an A2 blade regularly next to a high carbon, O1 or any other blade before you can make your final decision. For even with all of this well researched information before us, it comes down to our own personal preferences overruling the cold facts.

jim

[george wilson]

Google A2 steel advantages over 01. Every listing mentions A2's better wear resistance,and longer lasting edge.

[John Coloccia]

John,you say that you can't tell the difference between A2 and 01,and then say that the A2 certainly does last longer between sharpenings!.

I think you may have read that out of context. I meant as far as one getting sharper than the other. They seem about the same to me. The only steel I have that really gets consistently and significantly sharper are my Japanese chisels.

As far as which gets sharper, there's nothing in my shop that gets sharper than my Japanese chisels. I can literally split hairs with those. I can't tell the difference between A2 or O1. Both get sharp enough to shave. The A2 certainly does last longer between honings and I don't think that has anything to do with wear.

[george wilson]

Thanks for the clarification.

[Jim Paulson]

I feel very fortunate that you folks were willing to give me your perspectives and offer up pertinent research on this question. I also appreciated Jim's discussion on sharpening A2 steel on the Veritas Mk.II Power Sharpening System. Since I love using the worksharp, it was encouraging to hear that I could handle the A2 as well. You have given me some ideas about the various stones I could utilize after honing on the worksharp.

As someone who is no stranger to using ceramic, water stones, and diamond stones for sharpening, I really benefitted from all your insights here. I have a greater awareness too of the knowledge base you provide this forum.

Many thanks for your helpfulness,
Jim

[Sandy Stanford]

Hi creekers,

I've got a 605 bedrock plane that I'm restoring to use with a shooting board. The plane cleaned up real nice and the only thing I'm changing on it is to add a replacement blade and maybe a new chip breaker. I want to beef up the iron thickness with a Hock blane. What do guys recommend on the blade steel? My preference has always been to get my cutting edges razor sharp, can I get that with A2 steel or should I stick with my gut and go with O1 steel?



http://www.chairsbypaulson.com

I'm absolutely convinced that I cannot get A2 to as sharp a state as O1. I've been at this game a while. No A2 for me. Further, I don't like having my sharpening media dictated to me by the steel.

[Andres Sender]

Since my favorite blades are M3 and my aspirations currently point more towards M2 and Japanese steels, I don't have much to add directly to this question, but I think Brent Beach's plane blade tests provide some useful data points. To me the differences between O1 and A2 seem relatively subtle, although as time goes on I am less and less a fan of run-of-the-mill O1 (which Lie-Nielsen isn't).

http://www3.telus.net/BrentBeach/Sharpen/bladetest.html

I can't resist indulging in a brief philosophical detour however: if you’re not letting your steel dictate your sharpening equipment, then you are effectively letting your sharpening equipment dictate your steel, which in terms of practical effect is potentially even more limiting.

I don’t mean that as an assault on anyone’s preferences. Many factors affect one’s choice of tool and I have great respect for many craftsmen who have mastery with very different tools. :)

[Sandy Stanford]

Since my favorite blades are M3 and my aspirations currently point more towards M2 and Japanese steels, I don't have much to add directly to this question, but I think Brent Beach's plane blade tests provide some useful data points. To me the differences between O1 and A2 seem relatively subtle, although as time goes on I am less and less a fan of run-of-the-mill O1 (which Lie-Nielsen isn't).

http://www3.telus.net/BrentBeach/Sharpen/bladetest.html

I can't resist indulging in a brief philosophical detour however: if you’re not letting your steel dictate your sharpening equipment, then you are effectively letting your sharpening equipment dictate your steel, which in terms of practical effect is potentially even more limiting.

I don’t mean that as an assault on anyone’s preferences. Many factors affect one’s choice of tool and I have great respect for many craftsmen who have mastery with very different tools. :)

That's a set up for a grand game of tail-chasing, an activity in which I have no doubt many are more than willing to engage.

[george wilson]

I like A2 just fine,but for the projects I have posted here,I used 01 and W1 steel blades. it doesn't really matter what tool steel you use. It is your skill that matters. For production situations like my punch press stuff,it is a different matter,and I much prefer the longer lasting metal so I don't have to replace punches and dies when I'm too old to do it well anymore.

[Wes Grass]

'Adhesive wear'. On wood? Seriously?

I think they're talking about galling.

As for A-2, I too have made a bunch of tooling from it. Hard to grind? Try some Graph-Mo from Timken ;-)

[Bob Glenn]

Ah, George, I respect your experience and knowledge greatly, however, with a wife nineteen years younger than you, why are you spending so much time jousting here about tool steel? :rolleyes: You didn't think you could slide that by us with out at least one comment, did you?

BTW, I just had some A2 hardened and it is a complicated process.

Thanks for all your input to this forum.

[Leigh Betsch]

I built a bunch of blades out of A2 and had them professionally heat treated and cryo treated. I'm not going to take the time to do a real study on what type of steel is best for plane irons, so I jumped in and went with A2 based on my toolmaker days. But what do you experts think of D2? I avoided it because I'm really not set up with the proper tooling (carbide and coolant) to mill and grind it at home. But it seams to me it would make a great plane iron if a person wanted to put the effort into it.

[george wilson]

I have made knives out of D2. It is very tough to machine with its approximate 12% chrome,and other alloys. Not quite enough chrome to get it into the stainless steel category. It is also a steel that can be brittle. It has the peculiar trait of not feeling as sharp as it really is. I can only sharpen it with diamond stone,followed with a black and a white ceramic stone. Other stones I used to use weren't hard enough to get it razor sharp.


You don't want to go twisting on a D2 blade.

D2 was developed as a highly wear resistant steel for steel shearing blades. It has a feature of showing multi layered triangle shaped crystalline structures in it when it is mirror polished.

I think that A2 is going far enough for plane irons,myself. The longer the blades wear,the more time they take to sharpen.

Steels like high speed steel have too coarse a grain structure to get as sharp as simpler steels.

As for my wife,it's my age,not hers that keeps me here!! She wanted an artist husband.

[Larry Frank]

I have been reading this thread with some interest. It should be noted that A2 tool steel is a very complex material and sensitive to how it is heat treated. Granted this seems a bit of a strange statement for material that hardens in air. However, the subsequent treatments such as anneal or cryogenic cooling have a large impact on the final properties. Without extremely careful treatment, the material could have quite a wide range of final properties. The same comments can be made for all of the tool steels. One is really left with trusting a good name producer of tools to make certain that the material has been properly treated.
The term HSS or high speed steel also has a very large range of compositions and potential variations in properties. Without knowing exactly which HSS you are dealing with and how it was heat treated, it is not possible to even begin to generalize on its properties or how it might work in a woodworking situation. If someone is curious about some of the compositions, you could look it up in the Wkipedia or some of the other sources that you would find with a general search.
Most people are not really interested in the exact composition or how a steel is heat treated but only the final properties. With my background as a metallurgist, I do find it interesting. However of more importance to me, I just want a blade that is sharp, reasonable to sharpen and consistent in properties. It appears for my uses that A2 makes very nice shavings and produces a good surface on the wood.

[Jim Paulson]

Being a former geologist and an amateur blacksmith, I've really enjoyed the input provided here. I'm fascinated with metalurgy and I'm on the same page with Larry. I am more interested in purchasing a blade that was carefully treated by others and one that I can make sharp.

Since I don't have a microscope to look at the steel or the time to do that, I'm glad others have done that kind of research. Bottomline, I'm going to give the A2 a try in my Bedrock 605, but when it comes to making my own blades to be used in wooden molding planes I'll have to stick with O1.

Jim

http://www.chairsbypaulson.com

[James Carmichael]

Oye! Here we go again! May I recommend to the moderators that we post this as a sticky?

A2 is harder and will hold an edge longer. The tradeoff is that it is more difficult to sharpen, and it usually costs a little more.

Unless you're opening a 19th-century cabinet shop where you will be planing 100s of BF of rough lumber every day, either iron will serve you well and will outlast you.

[Ron Hock]

Here's the "official" line regarding O1 and A2 from Hock Tools: http://www.hocktools.com/A2.htm

The only thing mentioned in this thread that I must correct is the misconception that A2 is "harder" than O1. A steel's hardness is a function of the heat treatment process and either one can be tempered harder or softer by choice. A2 is "tougher" -- less brittle -- than O1 (at the same Rc hardness) which accounts for its edge retention reputation. I know it's a fine point but that's where this discussion ends up: two great steels differentiated by their fine points.

[george wilson]

Yes,any steel is as hard as you leave it from tempering. W1 will actually get harder than anything else I have used. It will reach 67 RC,if I recall correctly.

However,excessively hard steels don't hold an edge too well because they are also too brittle,and the tiny edge breaks off.

60 RC is too hard for 01,in my opinion. I made a blade of 01 and tempered it at 60 RC. It never kept a good edge. 58 is a better figure,or even 55.

[Ron Hock]

All of our plane irons are and always have been hardened to Rc62.

I suspect your blade's poor performance was a result of the hardening technique, probably overheating which causes the growth of large, fragile grains. The piece will still test properly hard but the large grains make it very fragile and the edge will crumble easily. If you break a piece of steel that was overheated, the large grains are visible and will look sparkly. Properly treated steel will look matte gray inside, like gray primer. It's an extreme test, but if something should break, take a close look. You can often see why.

[Sam Takeuchi]

If you get a craving to try different blade in the future, give Tsunesaburo laminated blue steel blade for bench plane a try. It's in the range of Rc 66 - 67, still high carbon blade, but definitely lasts longer than other high carbon blades I've had dealings with. Yet, it's laughably easy to sharpen since the majority of 'meat' is soft iron. There is a great balance between edge retention and ease of sharpening. Simply a beautiful blade. The only drawback is that it's not as thick as other replacement blades. It falls right between stock Stanley and replacement blades offered by Ron here and LN, but it can be coupled with thicker replacement cap iron it works very well. It hasn't chattered on me in several months of use so far. It's simply a wonderful blade and I think if you like O1, you'd love this blade. It is available from Japan woodworker as well as few other places.

I don't notice any chipping in normal use on soft and hardwood. The only time I got a bit of chipping was when my stock was loaded with silica, but that would've obliterated commercially available A2 blade just as well. For that, I use M2. While I like M2, it's not for everyday woodworking.