Re: very cheap (read: free) bases for your next gantry project

> >What is a *surface plate*, foreigner wants to know :)
>
> rectangular block of granite, ground and polished to a good

tolerance,

> say 0.000 inches or better. Used as a calibration standard

for "flat"

> in a machine shop. They come in different grades of flatness.
>
> Typically about 3 inches thick at the 12 by 18 inch size.

Thanks Harvey,

Now I know :)
I have one *Collins Micro Flat* inspection grade.
36"x24"x5" Heavy as hell (300-400kg), not suitable for small machine.

Bengt