hardness test samples

M

maxegb

Joined
Apr 17, 2000
Messages
108
Hi everybody,
I started to work on some knives reviews (stay tuned for an extrema ratio breaking in the competent forum),and i was looking for a reliable (altough empiric)way to check the hardness of the blades. My eyes fell on an automatic center punch that i found in my hardware store. Basically it's a spring loaded punch, so the amount of force that it uses to mark a center it should be more or less the same everytime.Now,since the force is always the same,if i have a sample of metal of unknown hardness i can use the punch on it and then compare the resulting mark with control samples of known hardness.Maybe i will not be able to spot the difference between 59 and 60 HRC, but i will give it a try.The problem now is to find samples of materials that have a known hardness,or a list of usual hardes for common items (such as a file or a drillbit...) Has anyone got any idea?
Thank you!
 
Max,

One problem you will have with this method is that the tip of your centerpunch will not be hard enough. After several "shots" on a Rc 60 blade, it will no longer have a point!!! On the blade it probably won't leave much of a mark even on the FIRST shot. A Rockwell tester uses a diamond tipped probe to test hardness.

The next best thing to a Rockwell tester is a set of hardness testing files available at most of the knife suppliers including www.Sheffieldsupply.com


Neil
 
thank you.Actually i tought about that and i was wondering what i could use to substitute the tip. maybe a widia drillbit (are they called wiadia in USA as well ?).
 
I think your idea is worth a try, but it may be hard to get accurate results.
Another method used to estimate hardness is the file test. Files very a lot in hardness, so you will need some samples of known hardness to compare with.
The method that I like is the scratch test. To scratch test, you scratch your sample with the point of a knife; if the sample is scored, it is softer than the knife point, if it is not scored than the sample is harder.
 
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