Marble top (20" X 30") for measurments


#1

Hi,
An acquaintance is giving away a milled Marble top (20" X 30"). We can use it as a measurement table for keeping gauges, etc (keep it on one of the tables).
Good for measurement prior to Lathe or CNC machining, aligning, and checking parts after machining.

It was at the top of a coffee table, it has a couple of faint water stains. No chips, dings or
cracks. Very heavy, so I will need a hand to move it.
Please let me know if interested.

Thanks,
RK
Marble_Top_Measurement_Table


#2

I wouldn’t expect this is actually reference-surface level flatness, no? Marble is only half the equation, for its temperature stability.


#3

Marble naturally cleaves into flat sheets, so we can assume almost reference level flatness.


May be we can measure it and see?

Thanks,
RK


#4

The tools for validating the flatness of large surfaces are very special and expensive. I’d be very surprised if it was within 0.025” over that size, which isn’t very good. Proper surface plates are thick so they don’t sag, and wear is also a big issue. High precision surface plates will get lapped and calibrated at regular intervals by specialized outfits with a high accuracy inclinometer.


#5

I guess the question is…

In the absence of anything flatter at VHS, would this be useful?

Are there projects where one would want to reference against a very flat surface, even if it’s not a super duper flat surface?


#6

Hi @lukecyca
In the absence of anything else flatter, this should do!
It can be of help to CNCers, especially for small parts.
Best,
RK


#7

I do not think that this would be useful. It is not likely flat enough for any practical use. Small granite surface plates are actually very cheap… $50 range.


#8

I can’t believe nobody posted this yet…


#9

Alright, then I vote we don’t bring this marble top in.


#10

In the absence of any decent water or oil stones It’s probably flat enough for scary sharp tool sharpening in the wood shop…


#11

We’d have to expand our supply of bandages if we go that route.


#12

If nobody else wants it, I would love to pick it up


#13

I have asked the donor if it is still available, if yes, will let you know the pickup place.


#14

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