Sheffield Micro Vickers Hardness Tester...

[gnomon]

Hi,

I just acquired a Sheffield Micro Vickers Hardness tester model MVK-C. It was made in Japan around 1956.

I am missing a few parts, the light source that illuminates the test impression, the objective for the filar microscope, and the weight disks.

I could use some clues as to what power objective, what sort of light source, and weights I need to complete my machine... Anybody familiar with this machine?

Thanks!

Chuck Harris

[Gordon]

Hi Chuck

to the Surface Engineering Forum.

Sorry, never come across this one before. A quick search revealed nothing except "Akaishi" instead of Sheffield, but that didn't lead to anything either.

Generically microhardness testers have measurement optics giving around X500 (+/- 100) magnification. Main objective lens ~X40 or X50 and eye piece around X10 or X12.5. Usually, a second objective lens around X10 used for viewing/spotting at X100 magnification is included.

Light source typically halogen bulbs ~20-50 watts, usually filtered to give green light (for better contrast). Usually there will be some form of condenser lens, iris, filters etc associated with this.

Weights normally placed directly on top of indenter mechanism so they should be roughly a similar weight to the the intended applied load (- natural indenter mechanism load).

Good luck in your search.

[gnomon]

Hi Gordon,

Thanks for the reply.

I found one reference to the MVK-C associated with the Akaishi name too. They are probably the true manufacturer. In 1956 Japanese companies weren't held in high regard in the US, and much of the rest of the world, so it was common for them to take Anglicized names.

I have seen 4 or 5 papers on the scientific paper mills that reference this machine, but not wishing to pay big money for simply a glimpse of the name, I have passed over them ("... we used a MVK-C Micro Vickers Hardness test set to measure the film hardness of...").

A main objective of X40 or X50 gets me into the ball park. Would that be a Planar (Plan), or an Achromatic objective? I would guess Plan because the planar objective gives a flat field over 90% of the viewing area. Most of the microscope objectives in the X40 or X50 range are oil contact types. I would presume that this instrument would be using a dry objective.

I guess I will have to measure the filar eyepiece and see what objective is necessary to make its graduations come out in decimal mm.

As to the weights, is it typical to use only a single weight on the platform, or is it common to stack weights to reach the final indenter weight? If only a single weight is used for each measurement, than each weight would need to be reduced by the indenter/platform weight. Or if multiple weights were used, I would expect that the lowest weight would be reduced by the indenter/platform weight, and the rest would be marked with their true weight.

Thanks!

-Chuck Harris

[Gordon]

Hi Chuck

I think you have answered all of your questions there I think a single weight is normal for each testing load, but I suppose multiples could be used if the indenter mechanism alone is balanced out at zero.