granite countertop for flat sanding?

[INEEDAGN]

I know it wont be as flat as a high dollar granite surface plate like you'd find in a machine shop, but for the purpose of flat sanding trans/engine parts, would a used piece of granite countertop be flat enough to use?

I had my machinist buddy surface grind me a bad ass straight edge and I was gonna carry it into the "local" habitat for humanity re-store and check the flatness of some used pieces, thought i'd ask here first. It's cheap enough to justify vs. the drive to my old employer (who does have a granite surface plate about 3' X 4'). $10 per square foot.

 

[TexasT]

I'd use it but hey, I'm cheap.

Posted from the TurboBuick.Com mobile app

 

[INEEDAGN]

That's what I was thinking! Lol

 

[McHaggis]

I use 1/2" thick plate glass. It's sometimes referred to float glass (in NZ) so its dead flat. Works great and as the glass shop considered my 18" square piece scrap it was free. Even better!

 

[turbo nasty]

I use a old big marble lamp base. I checked it with a machinist straight edge and its flat as flat