Hand Tools Archive

Re: The discussion on wire edge and deflection..

david weaver
..is very esoteric. We generally consider O1 to be a very plain steel. I like it a lot for plane irons as long as it's hard enough, or in general at any reasonable hardness for anything other than smoothers (from last week's discussion about good-working jack and try plane irons not needing the biting hardness at the edge).

What's surprising is tempering these things at 350 degrees in the air fryer, seeing that they come out with the very light straw that you're expecting and then a foil is raised on the O1 off of the buffing wheel (I use a 5 micron al-ox compound from mcmaster carr - it's cheap, and has enough influence that you're not just dawdling, and it also ends up cutting very finely because it's on a buff) and it hangs on with the O1, but not the other knives.

It would come off in use, I'd think, but it's annoying to look at because it looks like a breaking edge, and you should confirm that it's just wire edge by jeans stropping or something and then visually looking at the edge to see that it's disappeared.

Before sharpening razors made of O1, I considered it to be probably a good steel for them because it's so plain. But compared to what's in good razors, it's not nearly plain enough. You can drive up hardness to relieve some wire edge holding tendencies, but that won't solve the problem when you hit an edge with the strop on a razor - the very last bit of edge is the important part and that part needs to hold up to the leather, release any loose bits and then wear a tiny bit. O1 just isn't good at it.

I think that these qualities are what makes the very old very plain water hardening steel dreamy when people run into it (like wiley discussing the older moulding plane irons and just how they sharpen. These characteristics are very useful on a moulding plane iron where you just want to sharpen the profile and not faff with much of a wire edge, and you certainly don't want chipping because of the difficulty in moving the edge back by grinding or heavy honing).

In practice, white II steel hardened between normal japanese and western chisels behaves like I'm discussing above, and is not particularly fragile. The iyoroi mokume chisels that I mentioned take some flack for being less than full hardness for japanese chisels (they are probably 63 or something, they're still harder than western chisels), but they feel a lot like old steel.

I sort of get tied up thinking about this stuff because I like making tools, not because it's really that useful for someone who is just making things out of wood. It's probably not.

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