Hardness Testing

I am emboldened. Much of my thoughts about what I can feel with hardness, and how consistent I can feel it is supported by the hardness tester.

This is a boast, as George Wilson used to say, when you can do something, maybe it’s still boasting, but it’s true.

But this means ultimately, you could do it, too, as I have no real special talent other than curiosity and plenty of people on the forums will confirm that if you ask them.

I will put up a separate post about the hardness results that I’ve found in a bonanza of testing over the last several days, but they also help to confirm other thoughts of mine – that older English tools aren’t any too soft.

Thus far, of the chisels and irons that I’ve liked, and that are well received, only one tested below 60 (a parer that I’ve used little). Everything else has tested 61.5+.

A few other things have solved mysteries that I thought maybe I just wasn’t perceiving correctly, and a pair of boutique irons that I always thought were a bit of a bear compared to their specs (hock O1 france and LN spokeshave iron) tested at 64 hardness. I struck them both over and over to come up with the same thing.

I think it will be an interesting thing for us to look at as I compile test data.

The tester that I purchased is a hand held tester that can be used in a stand, but it is a full strength diamond cone tester, just like the upright stationary types. There are some nuances in handling it, but anyone who can sharpen a plane iron freehand would gather these quickly, and then the device will return a value that differs by well less than a point on the C scale every time.

Lastly, the device has confirmed that the things that I think i can do well (26c3 steel) and consistently are really close. Every single 26c3 item so far has struck at 63.5 except for one, and that remaining item struck a test result of 64. I’m so pleased to see that because I can scarcely perceive any hardness difference between any of those four, except I did perceive the 64 result as being slightly hard. But I could have also been telling myself that because it was heat treated twice and got a little overtemp on the second try. I certainly wouldn’t claim to feel 1/2 point.

At any rate, this tester will help us bust some myths, and it has already helped me clean up two steels I was coming up short on with the induction forge.

What we see in test results and now my addressing those shortcomings, and then confirming that how I get hardness where it should be doesn’t lead to a poor outcome is a good topic for a future post, because it will help you do the same if you’d like to try your hand at heat treating, but you’re reading too many internet articles that tell you that you’ll just find uncontrollable grain growth or lack of hardness.

I will give you some advice on how to get reliable sampling without having to buy $700 chinese hardness testers or induction forges. All you’ll need is a good file and willingness to make test samples with offcuts and look at them under any inexpensive magnification.