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Blade Selection and Preparation
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As a part of our steel selection process, we developed a long list of candidate
alloys for testing. From this list we selected 15 different metals: two cast tool
steels (O1 and A2) and 13 powdered metals (PM). Six of the PM blades used two different
heat treatments, so in total there were 21 different blade configurations tested.
The materials were assigned code letters, so during testing we did not know which
metal was being tested.
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All blades were prepared in the Veritas Tools machine shop to the standard Veritas
Tools specifications used for blades:
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 a lapped face finish of less than 5µin
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a micro-bevel surface finish of less than 16µin
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The blades were checked for conformity to the specifications before initial testing
began. The blades were tested to measure their hardness as a result of the heat
treatment process. Hardness tests were done in four locations on each blade to ensure
that the hardness was consistent throughout the material. For the materials used,
hardnesses ranged from Rc54.1 to Rc64.4. As points of reference, the O1 blades averaged
Rc60.5 and the A2 blades Rc60.6. Following hardness testing, the blades were reassessed
for conformity to specifications.
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The next step was to sharpen the blades. For consistency in sharpening, the Veritas®
Mk II Power Sharpening System (PSS) was used. The blades were tested at bevel angles
of 20°, 25°, 30° and 35°. The primary bevel was ground down to 17° using an 80-grit
micro-abrasive. The micro-bevel was honed using a four-step process with 100µ, 40µ,
9µ and 5µ grit papers. The lap side was continually honed using 15µ and 5µ papers
to remove the wire edge. After sharpening, the surface quality was measured on both
the lapped and micro-bevel surfaces. All blades were sharpened to within the baseline
of 3µin on the micro-bevel surface.
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