I’m hoping that I’ve got the correct Philip. Looking at your website (nice work, by the way), I noticed that you are using D2 tool steel for blades. In my classes we make a couple of small planes and recently began to use A2 steel for the blades. Until this year I used oil hardening steel and because of the fire hazards of quenching in oil, I decided to change. Can I ask why you chose D2 as opposed to A2? I have little experience with the air hardening steels and would like to learn more.
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Shop, for oil quenching there is a suitable oil that does not pose a fire hazard-I suggest you ask an engineering supplies shop about it.
I have not exclusively selected D2 over either O1 or A2: I like to use the 21/4" A2 blade from Veritas since I make a smoother to fit this proven blade.
I also want to use D2 because it has suitable properties and is well proven , provided the heat treatment is appropriate- therefore I leave this to professional specialists such as those in the aircraft maintenance industry: it is well regarded here. Although it can be hardened by oil, air or hot bath methods temperatures required are much greater and more exacting. I would say the main reasons why I want to use D2 is because it has been around since WW1, has been proven and I have a stock of 2" stuff from knife making days.
These steels and some others are good for us, they all have pros and cons, but I believe that a critical factor is the heat treatment, and here one can say that O1 is the only one suitable to treat "at home".If you are to get the maximum from steels other than O1 I reckon it essential that the heat treatment is left to professional specialists .
I would not go off O1 because of that reason you mentioned.
I don't want to start a skirmish about these steels- all the information and mythology is well documented and folk can make their choices freely....
Philip,
Thanks for the response. I will check on the oil. I wouldn't want give the impression that we are experts - we are not. Part of the class deals with heat treating so I can't "contract it out". Over the years I've had good results with O1, now we've had decent luck with A2 and I would like to try D2 if there are some significant advantages.
According to the Tools For Working Wood catalog, D2 steel does not hone well with Shaptons, but are fine for Norton waterstones. Don't know why, I'm just passing along the info.
Daryl, that is interesting. I suspect that the D2 they tried may have been hardened to well over RC61, in which case it can be more brittle than we would accept.
Looking at various engineers references here I see that D2 is normally hardened to a maximum of RC61, whilst A2 can come out at 63 and O2 can get 64.One should not assume that the hardest is best -for woodworking edge tools.Philip Marcou
No - that's not it - the hardess of the D2 was normal. It's just that the D2 is tough and wears out the abrasive before the very hard, not very friable shapton stone releases the grit from the matrix. You can do it but it takes far longer than it does on a softer, more friable stone.
I've noticed that the A2 becomes extremely hard - to the point it will break when dropped. We follow the directions and temper twice, immediately. My calculations show a hardness of 60C. I can understand how blades could be too hard. If D2 is similar, the tempering becomes more important.
Yes, that makes sense. D2 has 50% more carbon which makes it potentially more brittle, which is why I maintain it should not be tempered as hard as A2. Since it has more carbon etc it has better wear resistance, but less toughness. Quoting from a chart here on a scale of one to ten we have D2 with a wear resist factor of 8, as compared to A2 with 6, and O1 being 4. Onthe other hand for toughness D2 rates 2, A2 rates 4 and O1 rates 3. But the thing to note is that these comparisons are made at quench. D2 also has the finest grain size, which is one reason why knife makers are happy with it.
So it's all a question of plus and minus once the shouting is over.Philip Marcou
Most steel manufacturers publish a wealth of data and give specific recommendations wrt. tool steel selection. For example Crucible Service Center give detailed information on hardness, wear resistance and toughness of O1, A2, D2 and many other tool and die steels (and pitch their specific competitive advantage).
http://www.crucibleservice.com/eselector/general/generalpart1.html
http://www.crucibleservice.com/eselector/prodbyapp/tooldie/t&dchemtbl.html
From these curves I conclude that (comparing A2 and D2):
* hardness is pretty much the same (in practice it is very difficult to measure Rockwell hardness with a margin of error significantly lower than +/-1 HRC)
* if you want to sharpen less go with D2 (slightly better wear resistance than A2)
* if you hit a lot of knots, go with A2 (better toughness than D2, by about a factor of 2)
(* as a consequence D2 will be harder to sharpen than A2, no free lunch there either!)One word of caution however:
* Other manufacturers' steel might perform differently
* Manufacturers spec tool performance for use in machine tools with lots of horse powers (kilo Watts for non US readers). The "initial sharpness" of a cutting tools rapidly degrades to a "working sharpness" until the tool finally becomes "dull". For hand tools the "working sharpness" would be considered "pretty dull".Here's a lightly new twist on the O1 vs. A2 vs. D2 vs. M2 discussion:
Maybe we hand tool users should consider two types of application, and wearing my engineer's hat I made up a graph to support my thinking (see attached).
1) smoothing (smoothing plane, infill pane, etc, red region): requires keen sharpness, easy to achieve best possible "initial sharpness", sharpen often to maintain "initial sharpness", toughness and wear resistance nice to have but of lesser importance.
2) stock removal (Jack plane, etc.; green region): requires superior wear resistance, sharpen as infrequently as possible, best possible "initial sharpness" of lesser importance.I believe the ideal blade for 1) is a traditional laminated blade (O1, white paper steel, blue paper steel or maybe even good old high carbon steel), with the added benefit of better damping properties as compared to current solid steel blades; the ideal blade for 2) is made of A2, D2, M2 or similar material (if you don't prefer to use a p@w*r tool for that task).Chris
Chris, thanks for those links- I had missed your post.You are right when you say there are no free lunches- it's a question of trade-offs and plusses and minussesto be weighed in with the widely diffeeing characteristics of timbers in this world.
I like those three, being O1 ,A2 and D2 and haven't found a problem with any.
A question for which you may the answer: I have some 1/4 laminated steel bars from which I used to make cutters for slotted collars for the shaper and have no idea what the hard metal is -what do you think it could be? It seems to be rust resisting, very hard, easy to grind with white wheel and takes a very sharp edge from slip or oil stones no problem. I think it is asking it be made into some smoother blades....It has the name of Spear and Jackson on it, but this does not mean they were the manufacturers.Philip Marcou
Philip,For what I know that could be pretty much anything, (as a scientist it hurts to type that but) why bother if it works? Let us know how it works out!Chris
>>> D2 also has the finest grain size,
Are you sure about that? D2 had the most chromium of the steels mentioned (~12% vs ~5% for A2 and ~0.5% for O1). This means bigger and coarser carbides, opposite of fine grain. That's why one can get a keener edge with O1 vs D2.
>>> which is one reason why knife makers are happy with it.
I also don't know about that one. There may be other reasons. I would say the combination of wear resistance and stain resistance (almost stainless steel characteristics). Also the image that it is a "higer performance" steel and is expensive, despite the fact that most folks have a hard time putting a good edge on it.
Don't get me wrong, I was a knifemaker once and used this steel a lot, but it is not "user friendly". You've probably heard this one: "D2, takes a lousy edge and holds it forever."
Take a look at 52100 steel. It's ball bearing steel I have made a lot of chisels from old bearings . Tempering at 375 will get you 61 Rockwell.
John
Sharp, I am sure about the comment on grain size, as it is what I have observed when comparing D2 with O1. As for the grain size of A2 I have no practical experience, and am not inclined to try snapping a Lee Valley blade.I also have a knife making book with data summarised from the book "Tool Steels", by Roberts,Hamaker and Johnson, published by the American Society for Metals, so relied on the information on A2 in there to come up with the comment that D2 has the finest grain stucture of the three at quench.
Apart from enhancing stain resistance and colour, the presence of Chrome means to me increased hardness penetration and the fact that it combines with carbides, making them harder which implies increased wear resistance. When upwards of about 11% Chrome is added to high carbon steel the wear resistance increases steeply- so both knifemakers and woodworms (even planemaking woodworms) should be happy....since D2 has much more Chrome than the other two.Actual grain size is also influenced by the amount of heat during the heat treatment process.
If one can't get a reasonable edge on D2, or any tool steel for that matter, there is something wrong with the steel or its heat treatment.
I am not advocating any of three over the others-just looking at differences that matter to us, and I am pleased that there is a choice-several more than just A2, D2 and O1 can be used for woodworking tools.Philip Marcou
From the sounds of this, I better stick with A2. The heat treating doesn't scare me but kids have a hard time getting a good edge. I guess D2 could make that problem worse.
Thanks.
Sharpie, for you or phillip,
So what do they use in the various well known folding knives? It seems that hardness is a often a sensible tradeoff to other functions, and sharpening should be a simple routine. My knowledge of knives in practice is:
Swiss Army, won't rust, cant sharpen (ive never owned one and wont)
Puma, very hard takes a while to put a new edge on, good edge but feels like it might be brittle
'Old Timer' beautiful very fine edge, but stains easily (mine has a lovely water wash on the long blade created by apple juice one day) - can miantain an edge with strop for a while.
Compared with Pfiel (chip carving knives) - dont hold an edge as long as the puma, but easy to maintain a carving standard edge with a strop - your hands need a break anyway.
Around the house and for carving I prefer the fine edge on the carbon steel of the Old Timer - keeping the edge sharp is much less hassle than dragging a thick tool through wood. I have about the same profile on the Pfiel.
Around the bush I carry the Puma - I dont carry a stone in my pocket and need to rely on it all day if necessary.
take care
Dave
Hi Dave,
The Pumas that I had (before they developed legs) were 440C stainless-stamped on them.As you say, hardish and don't seem to get all that sharp-typical of high stain resisting steel.I think Gerber and several others use or did use 440C, but they all keep coming up withe steels claiming to be superior to anything else.
Swiss Army- not sure what steel , but I still have the amusing image of several Swiss Army knoives pegged into the classroom floor-all broken off ....Very brittle, in fact one turkey even snapped his with his fingers.Don't even know if they are still like that, and was sick of the sight of them everywhere in Geneva- preferred to gaze at Rolexes etc there... Therefore in those days I spurned them, but I used to sharpen them for all the other lads-because it was easy to get a shaving edge (differing to what you said).The knives we liked then were Joseph Rodgers- good old O1 no doubt.
Never had an Old Timer, but suspect it is either O1 or W2 or L6.
P.S-never got an answer from Arthur Goodall....Philip Marcou
Edited 11/9/2006 8:07 pm by philip
Phillip
Thanks for the knife stuff - I asked the question because people seem obsessed with hardness. I could sharpen the old swiss army - it just didnt stay thaat way after opening two cereal boxes. Now for all those people on this thread complaining about US made (remember that I live in a country that is on the receiving end of US trade policy) It really is hard to go past your production knives - the leatherman has to be the best advancement on design since......
Pity about Arthur - probably worth dropping in when you are in town in the afternoon - I suspect that you would catch him after a couple of tries without much effort.
Remember talking about the difficulty of immigrating to Aust?
Came across a story (4/5 on the credability scale) the other day. An american on a student visa does a fine arts degree in furniture here. Completes as the top student and then tries to stay - remember we have a massive skill shortage over here and are trying to get skilled immigrants.
Apparently we dont need his skills, so he tries to get classified at the local tech college. They train to a max standard labelled '4', looked at his work and classified him a '5'.
Rejected by immigration because we only need 4s.
Dave
Dave, given the mentality of some of those turkeys employed by Immigration authorities I would say the story is believable, unfortunately. However, if the guy is determined, there is bound to be a way.
But the real problem is if the market and or the economy is not ready for up market woodworkers/cabinet makers/manufacturing artists they just will not flourish. Karl Holtey says he is yet to sell a plane in Australia because "they are not ready yet". At the time I had a sense of humour failure so did not ask him if he had tried New Zealand.
Is Leatherman still being made in the States?Philip Marcou
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