Hand Tools Archive

Beyond chipping for ideal hardness
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David Weaver
Obviously, there is a comfortable range that these irons will operate in. It's probably 58-63, though there's no guarantee in open atmosphere, my irons will get to the top of the range and be OK.

Also, chipping below a certain point is sort of subjective. An iron that goes from smooth edge to lines all over the place in 100 feet is probably too hard. But what about one that leaves a little line here or there, seemingly suffering nothing else. What I saw from these irons in the test, and with the two at 375 is they will leave little tiny lines, and then with a little wear, those lines go away. There are lots of reasons for this that may be more related to contaminants or material pinned on my diamond hones, etc, so I'm not sure about that.

But further than that yet is my desire to have something that rolls up a wire edge fairly easily because it is quicker to sharpen and easier to confirm that sharpening is done. That is a better iron to me - and I'm not sure what I give up in edge life, but it may be zero percent or it may be ten. I don't know. But I sure like sharpening the mule that went to 405 degrees temper than the other two that went to 375 temper.

Three irons doesn't really make for a good sample to draw conclusions from. It's still fairly difficult to get these irons to bright orange (really bright) and I pushed my second one of this bunch to the point that there were differing surfaces after heat treatment (did I cause some elements in the iron to surface? I don't know). So, the consistency that we'd want isn't there. After testing all three, though, the mule behaves really well and is a little softer. The other two irons are a little more hard tempered and indistinguishable in testing, and as I post this, they're already at 400 in the oven to see if they have the same pleasant behavior as the first iron.

By schedule, if I did things right, that may be 60-61. I don't use a machine shop around here, so I'm not aware of one without doing some footwork (if I was located where i grew up - rural - then machine shops and engine shops are easy to find - they're right in town.

I have the make process for one of these irons down to an hour and a half with my poor man's setup. It'd probably be easier for me to make you an iron to use and let you have it analzyed than it would be for me to track someone down close to here and drive back and forth to them.

I have the mule and one of the two to use, so I probably won't be making many more #4 sized irons, but I also have a record 8 and an old i sorby 7 to make irons for). The third iron here is headed out as a gift.

I just checked the oven and the second and third XHP irons got to 415 in the oven instead of the 405 that I was targeting. I don't think that'll be a big deal (the tempering chart for XHP shows less sensitivity around 400 and slightly above than O1 - actually, it's really insensitive. They also state that they don't recommend tempering below 400 degrees or above 800 (as I recall, that's nearing the range where chromium will start to do bad things if it's left to congregate).

Supposing this is actually the same steel that is used in V11 irons, I'm sure LV did plenty of testing to find out what temper they liked, and I'm sure their work is more legitimate than mine. I'm making a lazy man's iron.

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