In article ,
"The Davenport's" wrote:

Hi All,
I've gotten a Rockwell hardness tester without instructions. It seems to
be so simple but I'm having trouble figuring out how to use it. From what
I've found in web searches it seems that there should be a "minor" load
applied and then the "major" load applied by the weights and then back to
the "minor" load to take the reading. I'm not exactly sure how to apply
the "minor" load on my machine. I can turn the base screw to apply some
preload but that hardly seems exact. If anyone has used a machine similar
to this one and could describe the process I'd appreciate it.

pics at:
http://www.personal.psu.edu/kjm182/pics/hardtester/dial.jpg
http://www.personal.psu.edu/kjm182/pics/hardtester/overall.jpg

There is a handle on the lower right hand side of the frame of the
tester...roll it towards you...that will raise the load weight.

Set your pre-load so that the hand in the small dial is pretty well centered
on the dot. Do this with the big screw that your sample table is sitting on
top of. Then turn the outer dial until the dial is zeroed.

Now gently push that preload handle away from you and it'll go the rest of
the way by itself...when it stops, gently roll it back towards you and read
your value from the dial.

Done.

First off, just to be clear, I ain't the OP, just an interested
bystander with an observation/query about the item in question.

Correct me if I'm getting things cock-eyed, but...

This gizmo sounds to me like it's essentially a concept of "put in a
sample, work the lever to put a (presumably calibrated) amount of force
behind a hard (diamond?) point, then measure how deep the resulting dent
is and convert the depth to a rockwell number." Correct? Incorrect?
Somewhere in between?

I say this 'cause the discussion on preloading and zeroing the dials
sounds *A WHOLE BUNCH* like the setup for measuring runout on a shaft,
or brake rotor, or similar, using a machinist's dial indicator.

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