Granite Plate Inspection

Do any of you use a granite plate offline to check parts? If so, do any of you have a thread insert pattern on it? I am about to by one and am trying to decide what would be the most helpful hole patter to have. I was thinking about staggering some 3/8-16 inserts along one short edge about 3 inches in. 3ft*6ft*12inch granite.

JEFMAN over 1 year ago

Here, you can have whatever you want made, with a few definition plans:
https://microplan-group.com/en/negozio/accessories/inserti-filettati-e-boccole-su-granito-2/

CET of granite is about 6 µm/m/K (between 4.5 and 7.5)
Aluminium is about 23µm/m/K.
If the plate is screwed on the granite at each end, a difference of temperature could create a pitch (twisted) of the plate, maybe more important than the granite flatness...

If you edit the compensation matrix of your cmm, looking at the straighnesses LXZ and LYZ will give you a idea of the defects, even if it's on the guide ways and not on the whle surface.

Just a thought...
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kingsld1 over 1 year ago

You do have to be careful with threaded inserts in granite. It is very possible to overtighten and pull the inserts out. If the plate is outside your door, someone will do just that.
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Benedictj1 over 1 year ago

You do have to be careful with threaded inserts in granite. It is very possible to overtighten and pull the inserts out. If the plate is outside your door, someone will do just that.

Murphy's Law..lol it will happen. Only I have a torque wrench that will be there and This plate will be off limits to night shift..hahha The plate I have now has a T-slot milled through the granite. It was broken out years ago..True Stone offers a metal insert that looks promising. they mill a square groove and epoxy the metal insert in. seems like a good idea.
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kingsld1 over 1 year ago in reply to Benedictj1

Always thought Murphy was an optimist.... Although that why we all have jobs in Quality.
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lost_in_endicott over 1 year ago

Our surface plates don't have inserts. We use Tesa Hites with air assist. The inserts don't play nice with the air cushion.

On a side note, the last place I worked at made our own grid plates for the CMMs. 1/2" Mic 6 plate, 1/4-20 threaded inserts with 1" spacing. We even sent them out for hard anodize, and the assembly dept painted in the letters and numbers on the grid. They turned out nice, and I think they were still cheaper to make than to order complete.
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