Hardness Testing a Knife

[Sam Sloane]

Question to those that have experience.....

If I get a knife tested ( at the thickest part of the blade) does the included angle of the blade, even though it is very small, give results different than those of heat treated flat stock?

Thanks all,

Sam

[Sam Sloane]

hmmm.....silence......like being in a swedish forest in the winter.....

[grepper]

There... listen... crickets!

I don't have experience but I would assume, suspect (hope) that whoever was performing the test would square the knife with the indenter. I too would think that a glancing blow would not be ideal.

Is that what you were asking Mr. Sam?

[Mark Reich]

If I get a knife tested ( at the thickest part of the blade) does the included angle of the blade, even though it is very small, give results different than those of heat treated flat stock?

HERE is a very good overview of Rockwell testing guidelines and practices, including information on the perpendicularity of the indenter to the test surface. 

The problem with testing a finished blade is that the test will leave a huge stress riser. That little dent may not look like much, but it gives the blade a place and reason to break.

[Bud]

Just had an experience at work along the same lines as this subject. If the test surface wasn't flat to the indenter, we got a variance of up to 3 points Rockwell. These weren't knife blades but I'd have to think the same applies.

[songshun]

I do not have this experience, but I think it can get that according to the understanding of metal.
anyway, do it carefully