Question about hardness tester

[Jim McGuinn]

I have the chance to do some horse trading for a Rockwell hardness tester the problem is it reads in N & T scale I found a conversion table to C scale. Can this be used for knives.

 

[Mike Morehouse]

Jim, N and T conversions only work on thinner and softer materials. The tester will not have enough weight to be able to cause an indentation in hardened material such as knife blades.

 

[John Moran]

http://sizes.com/units/hardness_rockwell.htm
The 45N scale is designed to test hard thin sections such as knife blades or case hardened material. But its all about the "Load" and "Indenter". You need to make sure it has 3 weights on the hanger in the back, and that it has a "Sphero-conical Diamond Indenter". Also you need calibration blocks. If you have to buy the Indenter and blocks this could add another $300.00 to your cost.

If it only has one weight (15Kg load) and a "Ball Indenter" it will be like Mike said, only good for soft metal. Knowing where it came from, and what it was used for could be useful in making a good decision. Photos could also help. This is one of those cases where details count, and you have to know what your looking at.

John

 

[Don Hanson III]

You do not want a tester that reads N scale for knives. The first one I got was a Wilson superficial N scale and I never could get consistent results. Scraped it and got one that reads C scale and all is good.

 

[John Moran]

You do not want a tester that reads N scale for knives. The first one I got was a Wilson superficial N scale and I never could get consistent results. Scraped it and got one that reads N scale and all is good.

I have both and they both work good. The 45N scale was designed to test hard thin sections, and specifically measure the hardness without leaving a deep penetration. Inconsistent results could come from a machine that needs repair, incorrect penetrator, broken penetrator, or a host of other things, not what scale it is reading.

 

[Don Hanson III]

I have both and they both work good. The 45N scale was designed to test hard thin sections, and specifically measure the hardness without leaving a deep penetration. Inconsistent results could come from a machine that needs repair, incorrect penetrator, broken penetrator, or a host of other things, not what scale it is reading.

The machine I had was like new and had a good penetrator. It was explained to me that the superficial tester that uses the N scale is more sensitive and not ideal for thicker through hardened steel. Yes, both will work, but I found it better for me to get a tester that reads in C scale.

 

[Jim McGuinn]

Thanks for all the advice. I'll see how much t goes.