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:



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/So...s-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.