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Practical Results from Iron and Sharpness Testing

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D_W

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A shorter thread with no discussion of testing process, just results that I found in a careful test (none disagree with subsequently found published results)

Edge life by abrasive fineness

* Finer abrasives will yield longer edge life (even when you don't allow them to increase time spent sharpening or create arduous processes)

* cheats to try to get even quicker through sharpening (by sharpening the bevel side with a quick abrasive and then working the wire edge off with a fine one only on back polishing) do not yield a significant improvement in edge life over the coarser abrasive used for the bevel side

Edge Life by Type of Plane Iron - Long Grain

* The relative comparison of various irons in relative edge life (approximate) with O1 tempered to approximately 63 hardness as "1" in long grain are as follows:
- Ward high carbon - 0.8 (bummer, one of my favorites)
- O1 - 1
- japanese blue steel - 1
- A2 (lie nielsen) - 1.25
- Chinese high speed steel (approximately 64/65 hardness - versitron tested) - 1.65
- CPM 3V at 59 hardness (versitron tested) - 1.65
- PM V11 - 2
- CPM M4 at 64 hardness (versitron tested)- slightly greater than 2 (the overall winner in terms of durability)

Edge Life by Type of Plane Iron - End Grain
* O1 - 1
* PM-V11 - 1.1+, but no chance of achieving relative results similar to long grain

The end grain test was painful to complete because just testing two irons in one iteration (weighing shavings, etc), the cutting resistance from O1 in end grain made for sore wrists and planing of about 2000 feet between the two. You are not misreading the total, by the way - the irons involved planed about that much , or each just under 1000 feet or just over. End grain was tested on a wide board upright in a vise (not shooting with a plane on its side - planes work far better in end grain for completing a volume of work when they're used upright)

M4 was the durability champ in long grain, but planing resistance was high, thus V11 was chosen to compare the relationship for end grain.

I also don't think the results gained from further testing with CPM M4 would be that useful because it's monstrously expensive. Nobody would ever make an iron that cost less than $100 with it.

Thoughts on Sharpenability and grindability
* ward and O1 - grinds and sharpens easily on anything. Blue steel, close to that.
* A2 - a little less so than O1, even though relative hardness was similar (I didn't test softer stock plane irons because the lower hardness would confuse the results - it's easily possible for both to be the same hardness if sharpening a soft iron in the field isn't a need)
* chinese HSS and M4 - both were slow grinding, but reasonable sharpening. The m4 iron went back to its owner. I still have several of the chinese HSS irons. They are extremely cheap ($8), but some arrive in a fashion that users would never be able to get past to sharpen them properly. They're out of flat quite often and tested at 63-65+ hardness along the edge in several versitron strikes - way above their claim of 61 hardness.
* 3V - hard grinding and slow sharpening, even on diamonds. If there's edge damage, the slow sharpening and strong ability to hold on to any wire edge (even from a finish stone) is kind of a pain. The buyer thought the iron was 61 hardness. there's a back story here in that 3V knife spec is 59 and the hardener (paul Bos of buck knife fame) may have slipped up because 99% of what he hardened was likely 59. Edge life would be slightly greater at 61 (the steel's spec sheet says 61), but I didn't have the iron at 61 and it is an iron that's not easily purchased, and it's outdone for practical purposes by V11.
* V11 grinds at a slow speed, even though it sharpens very sweetly on anything once you get to the finishing step. It sharpens to an easier cutting resistance and brighter surface polish on wood than even hard O1 does - on a washita. The slow grinding speed may make it offputting, especially if someone doesn't use a power grinder. Not a big deal, but if you're planing dirty damaging wood like the limba that I showed in another thread (with silica), removing the damage may make you wish for O1

M4 and 3V are out of the question for natural stone use. The chinese HSS probably is, too, for practical purposes, and the quality of the edge on the A2 iron after it outlasted O1 was unpleasant - it fails suddenly as it dulls and split shavings and lines on surfaces are the result.

As much planing as each iron was capable of doing, i don't think any of the results suggest the need to replace anything. O1 achieved long grain durations between 800 and 2000 feet, depending on the board used. That's a lot of planing, and a 2 minute break will be warranted.

The point of the tests was to gauge durability and substantiate claims about V11 among others and supplement prior tests done measuring small wear strips with testing that actually went to practical failure (which for most heavy hand tool users will be the inability of a plane to stay in the cut without additional downforce - planes going in and out of a cut leave ripples behind no matter how much you try to avoid it - above and beyond forcing you to do much more physical work)

The ancillary sharpness testing proves more useful (which is why it was brought up in another thread), and at little extra cost. It also substantiates other prior tests done by other individuals that I thought might be questionable. I was wrong - my efforts ended up duplicating theirs.

I also doubted LV's claims about edge longevity and repeated the durability test to make sure the relative wear was the same in both (M4 was provided for the second durability test to find something that outlasts V11 - they're close).

I make no suggestion about what other people should do - this gives you a starting point if you're interested in something from a results standpoint. I've switched my metal stanley style planes to V11-like irons that I've made. It's made working with those planes a little more pleasant, but having dimensioned a couple of hundred board feet (by hand) since doing this test, I doubt it really makes any significant time difference. Using a power thickness planer would, though.
 

D_W

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It's just opinion, but CPM M4 lasted the longest (by a little) and sharpened well, but was relatively slow to grind and had a lot of resistance in the cut.

V11 lasted about 95% as long or something along those lines and was less slow to grind and has much less resistance in the cut, so if I was picking a winner, that would be it.

It bugs me a little bit when something is only available from one company, but that's the way it is.

I think O1 is still the best choice for someone grinding by hand, and overall as well as it still seems tougher than anything else (it'd be my first choice in a jack plane, too, because it's quick to sharpen damage out of).
 
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