M2 vs M42

[PJ Seiber]

I'm relatively new to this craft (2yr.). I'm wondering what your all's opinion is on the the best steel. Please chime in and let us all know what your opinion is. M2, M42. M42 with cobalt, cryogenic, Sheffield steel, and any other you can think of.

[Mel Fulks]

Real M-2 is good . There are ..or were , some supplier’s advertising that their steel was “ Same hardness as M-2” …..and it was , but it
did not leave a finish as good as real M-2 or T-1. Both are good , T1 will stay sharper longer than M-2. Cheap knives , even when
sharp ,often make for ‘tear -out’, as the steel is low. quality.

[Richard Coers]

Cheap knives , even when
sharp ,often make for ‘tear -out’, as the steel is low. quality.
Tear out is most often operator error in my opinion. Any kind of steel right off the grinder will cleanly cut wood. I mean the Egyptians turned wood after all and I assume they used some kind of hard copper alloy. I started turning with carbon steel, and once I learned to sharpen, even those worked quite well. Many will say you can even get carbon steel sharper. Carbon steel has worked for decades in a hand plane without tear out. Best steel? Of course each alloy can have benefits. It's like asking what the best car is.

[Neil Strong]

It depends...

Best steel in terms of edge durability?
Best steel in terms of edge fineness?
Best steel in terms of sharpenabilty?

On durability, you get different results with different cuts. I got the following results from my testing with heavy wing peeling cuts...


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With light finishing shear cuts you get a different result...



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With heavy push cuts in very hard woods I got a different result yet again...



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The Tantung (Tt) performs better with the heavy push cuts but I found it didn't take and keep as fine an edge for the light finishing cuts in which M42 performed much better.

Fine grained Tungsten Carbide will cut for considerably longer yet again but it is much harder to sharpen.

[roger wiegand]

Neil, I'd be interested in your testing methodology-- is it published somewhere? You are seeing much larger differences than I might have expected based on my un-measured, anecdotal use of gouges made of different steels. My observations are completely without controls or experimental design, so real data are quite interesting.

[Mel Fulks]

I’ve tested steel machine knives by using them like “drawknives” . The real M2 and up will leave a shiny surface and cut without a lot
of force. In employments some shop owners who were using the steel that came with the machine were dealing with tear-out by
running everything through sanders . I proved that with good steel , that was not needed. But perhaps Robinson Crusoe got a
satisfactory shave with a shell honed on the best island rock.

[Reed Gray]

For 90% of my turning tools, I have either D Way M42, or Thompson V10. Simply, they cut longer without needing to be resharpened. I use the Big Ugly tool, a scraper for all of my heavy bowl roughing, I might sharpen it every 10 or so bowls, or at the half day point. Gouges for finish cuts, since they will cut more cleanly than scrapers, and clean up with a shear scrape. I can't tell any difference between the D Way and the Thompson tools for edge durability. I haven't done production work in maybe 10 years, and started using them maybe 15 years ago.

robo hippy

[Neil Strong]

Neil, I'd be interested in your testing methodology-- is it published somewhere? You are seeing much larger differences than I might have expected based on my un-measured, anecdotal use of gouges made of different steels. My observations are completely without controls or experimental design, so real data are quite interesting.

Roger

I've posted my testing protocol and results elsewhere. I can perhaps do the same here on this forum in a separate thread, but not immediately due to other commitments that I have at the moment.

My workshop experience is that I don't notice much difference between the different steels (with the exception of tungsten carbide). My workshop practice is to sharpen a batch of bowl gouges and go through them one after the other until they are all blunt then resharpen them together before starting to use them again. So, I get ample opportunity to observe how each performs one after the other. I have all of the steels that we use and and I still use all of them equally often.

Tool manufacturers will claim that their steel or heat treatment will outperform the tools from their competitors by factors of 'X', but I've never found those claims to hold up in practice.

Novice turners shouldn't get hung up on the steel in their first gouges, nor their heat treatments. They are better off buying additional gouges at less cost and experimenting with different flute profiles and grinds.

As a personal preference I like M42 for finishing cuts and V15 as a work horse steel, but find that flute profile and grind make a bigger difference than the steel, as does also the type of cut being used.

I'll leave you with one significant difference that I found in my testing and that was between Tungsten Carbide and the other two commonly used turning tool steels; V10 & M42, which performed about the same with this cut on very hard wood. I found that TC definitely outperforms the other commonly used gouge steels, but it is of course a useless bit of information until TC bowl gouge tips become more readily available to us...:rolleyes:


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[John Kananis]

I'm curious if anyone knows where m4 (like the oneway mastercut gouges) fits into the mix.

[John Keeton]

I have D-Way tools (M42), Thompson (V10) and a few M2 only because the profiles of those tools are not available in higher grade steel. I turn a lot of hard maple and there is a great disparity in how long I can get clean cuts. I have to touch up the M2 tools after very few minutes, whereas the M42 and V10 retain a sharp edge for substantially longer. I haven’t done timed tests, but a guess would be a factor of 8:1. The M2 seem to take a nice edge. It just doesn’t last long. I understand that M4 is perhaps 2:1 on holding an edge over M2, but I don’t recall ever using it.

The cost factor of high quality tools is easily justifiable IMO. Except for some scrapers that don’t get a lot of use in my shop, I would never buy M2 tools if the profiles I like were available in CPM metal. I have asked Jimmy Allen of D-Way about making continental gouges, but he said they are just not economically feasible given the limited market.

[Brian Brown]

Yes, they are definitely selling stuff, but maybe this link would be helpful. I find their videos to be quite valuable.

https://www.youtube.com/watch?v=vcM6kStHhCw

[Neil Strong]

Yes, they are definitely selling stuff, but maybe this link would be helpful. I find their videos to be quite valuable.

https://www.youtube.com/watch?v=vcM6kStHhCw

Here is the chart from that video that Brian posted...


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It has M4 but not others like V10 that many of us use. Here is a chart that includes V10...


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I've added where I think
M42 sits on that chart.

Edge retention or durability is what we woodturners mostly look for in a tool steel.

That chart is from the knife steel nerds and includes many steels that are not of interest to us woodturners, but here is the article it is taken from with more information on their steels than most of us woodturners will ever want to know!

https://knifesteelnerds.com/2021/10/19/knife-steels-rated-by-a-metallurgist-toughness-edge-retention-and-corrosion-resistance/

PS You can see from that chart why I like V15...:)

.

[John Kananis]

What an amazing wealth of information you folks are. I've been eyeing up those d-way and Thompson tools, I'm going to add them 1 at a time as the need arises.

[Reed Gray]

I don't agree with his call on edge sharpness and the V10. The sharpening discussion comes up regularly, and the consensus seems to be that edge sharpness is pretty much the same for all metals that we use, but some are easier to get to that point than others. The tantung that I use on my Big Ugly tools is a coarse cast metal, but finer than the old carbide used on the older saw blades. I can hone it to an edge that will compare with any metal I have ever worked with. The CBN wheels have made a huge difference in sharpening. Sharpened on identical wheels, I can't tell any difference between V10 or M42.

I am not sure about the Oneway tools, though I do have one of their spindle detail gouges, and i tis one of the longer lasting edges. I had an old Packard gouge that was supposed to hold an edge '5 times longer' and didn't notice a lot of difference until I went back to an M2 gouge.

robo hippy

[John Kananis]

I found this and it seems (to me) the difference between m4 and m42 (from a metallurgical composition perspective only) is more molybdenum in m42 and more tungsten and vanadium in m4.

https://www.makeitfrom.com/compare/SAE-AISI-M42-T11342-Molybdenum-High-Speed-Steel/SAE-AISI-M4-T11304-Molybdenum-High-Speed-Steel

[John Keeton]

What an amazing wealth of information you folks are. I've been eyeing up those d-way and Thompson tools, I'm going to add them 1 at a time as the need arises.
John, the flute profiles Doug uses are different than D-away and one or the other may suit you better. I started with a Thompson V bowl gouge and wore it out over a few years. I am on my second one, but now prefer the D-Way profile. For spindles I prefer Thompson. I agree with Reed on sharpness. I sharpen on a 600 grit CBN and can’t tell a difference in the edge. On durability IMO it depends on the wood. It it has a lot of silica I think the 10V does a bit better, but that is pretty subjective on my part. They are both excellent tools and it really comes down to what works best for you. I have several of both!

[Neil Strong]

I don't agree with his call on edge sharpness and the V10. The sharpening discussion comes up regularly, and the consensus seems to be that edge sharpness is pretty much the same for all metals that we use, but some are easier to get to that point than others.



Sharpness is to some extent a subjective measure. My subjective judgement has been that M42 takes a finer edge and keeps it for longer than V10 when used for light fine finishing cuts.

I confirmed this when I undertook some controlled tests in which I compared several steels, including M42 and V10. Here are my results...

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But, V10 holds its edge for longer compared to M42 when used for heavy cuts...


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The Tt is the results is for Tantung, which outperformed both V10 and M42 on the heavy cuts, but didn't do so well on the fine finishing cuts.

The metallurgy explains these differences, but how a tool is used also effects the result, thus the difference between the light finishing cut performance compared to the results from the heavy push cuts.

These side by side test were all done on very hard Australian woods using traditional bowl gouges that were all ground on the same grit wheel (#360) to a 55* bevel angle. As John Keeton points out, flute profiles can make a difference in performance. All of the test gouges used in the above tests had parabolic flutes other than the M42, which had a V flute profile. I attempted as best as I could to control for any difference in flute profile.

[David Walser]

These debates are always fun and interesting. However, on the question of whether M2, M4, V10, or any of the other common high-speed steels used in making turning tools, can be sharpened as keenly as the others, this has been answered in the lab. One of the ways to reliably testing the sharpness of an edge is to use an instrument that measures the force necessary to cut through a standardized, calibrated medium. The less force this takes, the sharper the edge. (See, for example, the Edge-On-Up Edge Tester. There are other brands that use, more or less, this same method.) There are other types of instruments that measure the sharpness of an edge. My point is only that there are instruments that measure an edge's sharpness, and it has been demonstrated through the use of those instruments that all of these tools can be sharpened to same degree of fineness. That is, any differences in sharpness can be accounted for by the variability of one sample from another sample of the same metal, or any differences fall within resolution of the test instrument.

So, why do so many of us believe that one of these steels can be sharpened more finely than the others? I think two things are going on. First, each of us is a sample of one. Our experiences are unique to us. Your M2 gouge is different from mine, even if they were made in the same factory. Each piece of wood that you turn is different from the wood that I turn, even if it is the same species. Heck, each piece of wood that you turn is different from the next piece that you'll turn. Given all this variability, is it any wonder that we might have different impressions of how sharp an M2 gouge might be compared to one made from M42 or some other steel?

The second reason is really a subset of the first. It is that some of these steels are harder to sharpen than the others. When I started turning, a lot of experienced turners used high-carbon steel tools for making their finishing cuts. The claim was that high-carbon steel tools could be sharpened to a finer edge than the (then) new M2 tools. Well, that wasn't true. M2 tools could be sharpened to just as fine an edge. What was true was that the methods these turners used to sharpen their high-carbon steel tools didn't work as well with the newer M2 tools. So, it wasn't that the M2 tools couldn't be sharpened, it was that the turners couldn't sharpen them. I think, but don't know, that something similar is going on today.

[Neil Strong]

So, why do so many of us believe that one of these steels can be sharpened more finely than the others?

~:~

Because we know from experience that they can be sharpened more finely and, more importantly, that some steels hold a fine edge for longer. Not perhaps as much of a difference as some tool makers would want us to believe, but there are differences, otherwise why would anyone bother with any of the alternatives, regardless of any differences in the effort or cost to make them sharp?

What the cutting test like the CATRA cutting test (https://www.catra.org/testing-equipment/knife-edges/aet/) do for knives is standardised the conditions (eg % of silica in test material) under which a knife is tested for the durability of its cutting edge when used in a slicing action.


But, such devices in themselves don't tell in a single test run result is the more complex interplay between edge geometry, carbide size and tool presentation that we deploy in wood turning.

For those that might be interested in such things, the following article goes into some of those complexities...

https://knifesteelnerds.com/2018/06/18/maximizing-edge-retention/


Going back to the results from my light fine finishing cut test that I included in my post #17, and repeated here again...


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... the protocol that I used to measure the durability of the fine cuts was the continuous length of the fine shavings coming off the gouge. A steel was knocked out when the fine shavings coming off it fell below 1" in length, which is the point at which I considered the gouge had become too blunt for this cut and tear out likely to happen. Here is what I was measuring...


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The bevel angle on all of the gouges in that test run were ground to 55°, so that was a controlled variable. My interpretation of the results is that the finer carbides in M42 allowed the acute wing edge to cut fine shavings for longer than the V10. It took and kept its fine cutting edge for longer. On that test with that particular cut the M42 was definitely sharper than the V10 if the CATRA criteria of “How long will the sharpness last?” is used.

[PJ Seiber]

Thanks guys, this has been interesting to say the least. Very informative. Like I said I'm kind of a noob and as I invest in tools I want to get the best bang for my buck. I'm looking at more for durability and sharpness. A BIG THANKS AGAIN.

[John Keeton]

One other factor to consider - an edge is created by bringing together two surfaces. With most other woodworking tools, both surfaces are honed to an equal grit to produce a fine edge. In woodturning, typically our gouges are ground only on the outside surface. There are exceptions like the skew. If one of those surfaces has visible mill marks that are not honed away there is an inherent barrier to obtaining a fine edge. The flute of a D-Way gouge has been polished. Many or most other brands have not.

I haven’t reviewed this thread recently, but I don’t recall that being mentioned.

[George Yetka]

Metallurgy, is quite frustrating it would be nice if there was 1 steel to rule them all. Something that had strength, edge retention, antirusting, ease of putting an edge , etc etc. I find you have to pick your favorite 1 or 2 attributes for a blade and suffer on the rest

[Neil Strong]

One other factor to consider - an edge is created by bringing together two surfaces. With most other woodworking tools, both surfaces are honed to an equal grit to produce a fine edge. In woodturning, typically our gouges are ground only on the outside surface. There are exceptions like the skew. If one of those surfaces has visible mill marks that are not honed away there is an inherent barrier to obtaining a fine edge. The flute of a D-Way gouge has been polished. Many or most other brands have not.



John makes an important point here. It is well worth the effort to put a fine polish on the working end of the flute if it doesn't come with that. I can't see an existing thread on methods for doing that, so I'll add that to my to-do-list.

The other tool that we use that benefits from a polish on its working face is the scraper.

I've been making some bowl gouges recently and at the end of that process I take the grind/polish on the flutes down to a finer finish than I will grind the bevels to. An inch of polished flute will suffice for as many re-sharpenings of the bevel that most of us will need if we are grinding with CBN wheels.

Here is the latest one I have been working on, which has been made from tungsten carbide...


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Needless to say, when I'm doing side by side test runs of the different tool steels I bring the flute polish up on all of them to the same level of finish and grind the bevels on the same grit wheel.