Hardness tester questions

PEU

PEU

Gaucho Knifemaker
Joined
Aug 6, 2006
Messages
1,182
Last week I got an used hardness tester, after proper conditioning now reads the supplied test blocks to half point RC accuracy.

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I would like to know something about test blocks, the one that came with the unit its indented a lot more times than recommended its not easy to find a decent spot anymore.

1) Can these be resurfaced on a tangential grinding machine?
2) is it normal for a test block to have different reading on the outer perimeter of the piece? I mean not on the side but going away from its center it appears to be softer.
3) can the other side of the block be used? OK I will need to grind the top indentations to be flat, but should be the hardness on the back be the same?
4) is it possible to make an accurate test block on the shop? I was thinking of hardening D2 steel, tangential grind it and calibrate it with a couple of hardness testers.

I'm not in the US, otherwise I would eBay a new one in no time :)

Thanks!


Pablo
 
Just take the test block and sand the in dented side on a granite surface plate.Make figure eights just till you knock off the high spots and use the other side for testing.Also my test block reads the same at the edge as in the middle.

Stan
 
The blocks are supposed to be "Certified" to the marked hardness over the entire block, although if you have any play in the table or column on your hardness tester, you may be tilting the block a little perhaps, which could give a slightly lower indicated hardness.. Not sure, just a wild guess.


Stan's suggestion is probably your best bet other than ordering a new block, although you may need one anyway, if you keep getting significantly different readings from various areas of yours.
 
I also have a few blocks that are out of space.... don't see why you can't use the other side after flattening it out that's what I plan to do eventually..
 
Will try the sandpaper on a granite surface and try the other side. Has anyone tried resurfacing/regrinding the block?


Pablo
 
I would think you could surface grind it down, although im not sure how deep the hardness target spec is...
 
As long as its for your own personal use, I would kind of agree with all the above. Its supposed to be a very consistent 'material', so which side shouldnt matter too much. I would just do some verification tests (say 5) on the new size to make sure they are consistent within the given tolerance band. ( I would love to know what they make them out of and how they treat them). I would imagine if you wanted to make your own you would ideally want to start off with a PM steel. Good luck
Lang
 
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