Replacement plane iron

[Craig22]

I've converted my three Clifton planes to Ron Hock A2 cryo blades and chipbreakers. I started with the 5 1/2 and was so impressed I've done the same thing with my 4 and 7.

I know there is an argument that high carbon blades take a sharper edge than A2, but you can work for much longer with A2 before resharpening.

Expensive? For sure. Worth it? In my view for sure.

Hock has a good explanation about the differences between O1 and A2 cryo here O1 vs. A2

 

[D_W]

It's not that A2 takes a sharper edge, but for some people who don't complete sharpening, it may seem like it (it probably drops its edge easier).

What O1 does is wear more uniformly. In hocks two plane irons, the A2 should last about 25% longer than O1. That's the relative difference between my O1 irons and a LN A2 iron (I tested one of my irons later against a hock and it lasted about 5% longer, which is probably equivalent to zero in margin of error).

Someone with a grinder and modern stones probably won't care much about the difference between O1 and A2, but someone who is new and who can sharpen both equally might like the longer interval from A2.

This is what O1 looks like when it's out of clearance (functionally dull).


And A2



The grain of O1 is finer and it abrades a lot faster, which should mean that someone with experience would have a shorter sharpening interval with it. You can see at the very tip of the edge, the grain size coming off of A2 is visible, but for O1, the line just looks wavy.

The fine edge holding of O1 is a bit better (you'll have fewer small random chips), but anything that does significant damage to either will do the same to both.

The A2 iron edge pictured above is LN - which is cryo, like hock. If A2 doesn't get cryo treatment, apparently, the carbide distribution is more coarse (brent beach showed an LV and LN A2 iron edge a long time ago and you could see that the LV iron was more coarse at the edge as it wore - D2 is worse yet - and has a more coarse grain than A2 - more or less a similar steel with more chromium in it, so that's expected).

From a practical standpoint (the above is from a relatively controlled test - measuring length planed and weight planed to make sure both are in proportion), a decade or more ago, I had both Hock O1 and A2 irons and used a guide to sharpen, and used the same plane to plane a bunch of panels. The slightly longer working interval of A2 is noticeable if you do something like that (e.g., you'll notice that you get one and some more of the next panel done with A2 if you only get one panel planed to thickness with O1).

I've grown to like O1 better, but I sharpen a plane iron in about a minute.

V11 edge life is about double O1, and looks like this (the process to make it results in finer carbides than A2 - very uniform, gobs of chromium and wear resistance because of it)


But it's a bit of a trick to use a V11 iron in real day to day work and not damage the edge before it would've dulled from wear. If it's close in cost to A2, it's pretty much a better iron, though, and it's stainless.

 

[D_W]

The reason O1 looks smooth in terms of wear is because the grain isn't large enough to show up on the visible spectrum when wearing. Different woods can create different looking pictures, though. The above is beech planed, and this is what V11 looks like planing maple.



In both woods, it lasts the same relative length vs. O1 (and O1 has to be relatively high hardness for the proportion above). I'd guess LV's O1 irons lose about 10-15% of their edge life due to their softness vs. hock. If the two are 5 points apart by chance given their specs, it may be more like 20%.

(the wear strip on these irons is due to the cap iron deflecting the shaving upward after the wear area - it would be less well defined without a cap iron set closely).

For visual reference, this is A2 sharpened with 1 micron diamonds:


I can't find a picture of the O1 fresh, but they all look the same. Here's japanese blue steel:


subjectively, V11 is slicker through the cut (and feels sharper), I'm guessing due to the chromium in it. V11 performed so well in these tests that made a bunch of irons out of the same steel as it is and used them for a while (mine last about the same amount of time as LV's, which isn't a surprise). But O1 wears more uniformly and takes half the effort to sharpen (and if nicking is an issue, it grinds at least twice as fast with less heat) - ultimately, I find it a little bit more practical. If nicking occurs due to dirt or silica or whatever else (pin knots that have stuff in them), the abrasion resistance of the alloyed iron works against you and you more often go back to work with an iron that still has nicks in it.

There is definitely (without regard to alloy) a case for good irons when they're harder to take a better initial edge, and the same may be true for some of the wear resistant types. The edge will be better off of V11 when using a washita (it barely cuts it) and the surface brighter vs. hock O1, or any O1. A2 is out in that comparison because it hates Washita stones and some of the carbides get pulled out resulting in a dullish ragged edge from the start.