M42 Tersa knife blades are a grade of high speed steel with a high content of cobalt in the alloy. It is less brittle than carbide steels. Similar to nickel in hardness and durability Cobalt increases hardness, edge life and heat resistance.
Molybdenum: produces toughness and neutralizes brittleness of chromium. Also helps increase edge life. The difference between the M42 and the regular HSS Tersa knives is most noticeable in the footage obtained from a set before they are worn out When using in the main hardwoods. Along with that the M42 is ground differently than the HSS; it has a ‘micro-bevel’ (has been ground at 2 different angles, 2nd angle being about 3 degrees less).
M42 is less prone to chipping or breakage than conventional M2 on tougher applications. Rockwell “C” scale hardness for M2 is 61 to 64; M42 is up to 68. M42 is much harder to machine than M2
When machining a wide variety of hard and softwoods in window, door and furniture production – oak (red and white), cherry, maple, teak, walnut, afromosia, Douglas fir, yellow cedar to name a few. When running Tersa heads in joiners, planers, and moulders We have found that, for the most part, the M42 doesn’t produce a better finish, but it does last a lot longer when machining hardwoods. For woods such as teak, walnut, or afromosia, M42+ is the best blade available Most makes of machine such as Rojek. SCM. Felder, Wadkin along with other makes such a Scheppach and Sedgewick have heads that are capable of taking a Tersa M42 or Tersa HSS Knive blade When In the main Just machining soft woods on a planer thicknesser along with 4 sided planers we have found for the finest finishes is produced by Tersa HSS giving durability with the finest of finishes on this type of timber.