Need a HRC test favor

[JTknives]

I am in need of a favor if any one can help.

I have a hardness tester but it's not your standard penatrator style tester, it's an old scleroscope that drops a diamond tipped plunger on the steel and catches it on the rebound and translates that to hardness. I went through and cleaned every part when I first got it as it was reading inaccurate and all over the place. But I have come to a head scratcher and don't know what to trust. The tester came with a testing block that that says 92-94 shore Which is 66-67hrc. But when I test that block my numbers are all over the place from like 90 to like 100 shor. But when I test a knife blade it's solid and repeatable to within +-1shore. For example my D2 puukko I heat treated and cryo (1725° 30min,LN 5hr, 400° 2hrx3) came out at 90-91shore. I also just did a A2 kitchen knife that got the same treatment but had a 1750° soak for 30° and then cryo and befor tempering it reads 92shore. Befor cryo it was reading 87-88 which is right about book hardness for A2 it seams. Every once and a while i will get an errant number but 95% of the time it lands right in that range. 88shore=64rc and 91=65rc according to the conversion chart, http://www.carbidedepot.com/formulas-hardness.htm

So I'm wondering if I could heat treat and temper say 5 coupons each at a different temper. I will keep one half of the coupon and mesure the hardness and Wright the hardness on them and send you the other half to mesure to double check my numbers to see if I'm on track. Or I can just slip some cash in the package so you can ship them back. This will also give me a known gage block of sorts.

So if anyone out there has a dependable reliable HRC tester and can spare a few min to test some samples I would be in your debt.

 

[HSC ///]

I have a Goko Seiki at work, I can do it if you want.
It's not independently calibrated or adjusted,
We don't have a use for it at work, I'm the only one who uses it for my knife-making
I'd say it's within +/- .5 point

 

[SBuzek]

I can also test them for you if needed.
Stan

 

[JTknives]

Sweet thanks guys, I will prepare samples and send them you you. I might send them to both of you guys and include an envelope with some money so you can send them back if that's ok. That way I can test the same test blocks as you did.

I have been playing around with it today and after reading how the shore scale works I might found a solution to why my test block reads high. The shore scale is a measure of w5 water quenched and non tempered and that is 100 shore. Then the scale is devided up eavenly from that point down. I bottomed out the impact plunger by letting it drop on my finger. This let the diamond tip rest below the bottom of the tester. I then brought the tester down onto the test block. This creates basickly a zero rebound with the diamond sitting right on the test block. I then rased the plunger to get a reading and it was reading like 15 shore. I then adjusted the dile up till it read zero. Now when I test my 92-94 shore gage block and it reads perfect between 92-94. So I hope I have solved the mystery but the coupons will tell the truth.