A2 vs. High Carbon (O1) Our High Carbon Tool Steel is the finest-grained tool steel available and the finer the grain the sharper the edge. A2 is a newer alloy that will hold its edge longer; the alloying elements that increase edge retention form large, tough carbide particles during heat treatment. Its a little harder to sharpen and bit more expensive but if edge life is paramount, you cant go wrong with A2. But if ultimate sharpness and ease of sharpening are more important, high carbon steel will allow you the sharpest edge possible.
Which HOCK blade do I need for my Block Plane? We offer four different block plane blades in two different alloys. The first determinant is the blade width, either 1 3/8" or 1 5/8". The next is the width of the slot in the center of the blade. It will be either about 7/16" wide or about 5/8" wide. Available in our High Carbon Steel (HC) or Cryogenically Treated A2 Tool Steel.
1-3/8" wide Blade:
7/16" slot: BL138 (HC) or BLA138 (A2)
5/8" slot: BW138 (HC) or BWA138 (A2)
1-5/8" wide Blade:
7/16" slot: BL162 (HC) or BLA162 (A2)
5/8" slot: BW162 (HC) or BWA162 (A2)
Why are some HOCK Blades made in France? Way back during the Clinton administration, we ran out of room in our small shop in the backyard. Rather than expanding our capacity here, I started shopping for job shops that could make our blades, to my exact specifications -- alloy, heat-treat, finish -- as well (or even, possibly, better) than we can ourselves. After a considerable search, I was contacted by a small, family-owned factory in France that makes industrial cutters and surgical blades. We established an excellent relationship that we enjoy to this day. They make a large portion of our production with the balance still being made right here in the backyard. Their quality is as good and (don't tell Larry I said this) sometimes better than what we can do here and I'm proud to have my name on these blades.
Why are some blades black (dark gray) and some shiny? When we were making all of our blades here in our small backyard shop, they were all gray/black because we didn't grind them flat after heat treating. The gray/black is a very thin coating of iron oxide that forms during heat treatment. Several years ago, we started having some of our blades made by others (don't worry, the alloy and hardness specifications are the same); large shops that cut the blades with lasers and wet-grind them to thickness after heat treating. The thicknessing makes them nice and flat and shiny-bright.
We still make many of our products right here in the backyard shop (still mostly by Larry, even after all these years) and they're the ones now that are gray/black with our debossed logo.