Knowledge You Can Build On — Est. 1998
Hardness of steel
Bob Larson
>I am looking for an explanation of the designations for the hardness of steel used in turning tools. Most often I see tools that are M2 High Speed Steel (HSS). In the Woodcraft catalog there is a line of turning tools made in China which are rated R62-64. Anyone out there know what the difference is?
Re: Hardness of steel
DaveZ
>You have apples and oranges there ;-) M2 is a type of steel. R62-64 refers to the hardness of the steel(rockwell scale)
Re: Hardness of steel
john Lucas
>Bob
Each company has a hardness rating that they have determined is the optimum for that tool. Most turning tools are somewhere between 58 to 64 rockwell. files are in the high 60s and cabinet scrapers are much lower. Higher than 64 and they get brittle and won't hold an edge for turning because the edge breaks off. Lower than 58 or so and the metal is too soft to hold an edge. I'm talking mostly about turning tools here.
Since all the metal is different you can't really say just because this is 58 and this is 64 that the higher number is better. It depends on the steel. Your best bet is to buy tools from known companies and trust thier best judgement to give you the proper hardness.
The other solution is to ask about certain tools on this and other boards to see if someone has purchased them and either likes or dislikes them. o
