Granite cutting board from Homesense @ $16 Dimensions ~18" X 12" X 1"

Good for finishing surfaces flat.

Perfect for blueprinting the oil pump.

Good idea!

Excellent sleuthing Blue!

You can either spray glue various grades of sand paper to it or use this system of abrasive particles as the lapping media like these

http://www.leevalley.com/en/wood/page.aspx?p=33017&cat=1,43072

I wonder just how flat that granite really is?

I wonder just how flat that granite really is?

I'm thinking the same thing.

Less than 1.5 thou. I have read:

Source:

http://www.model-engineer.co.uk/forums/postings.asp?th=28101

"I also have a granite plate from Tesco. I checked it with a GOOD straight edge (a new "best" ruler) and could not get a 1.5 thou feeler gauge under it at any point on the surface. I reckon that it is good to a thou over its surface - more than good enough for workshop use.

The smaller ones - down to "coaster" size may be useful for confined spaces!

Bizibilder"

Less than 1.5 thou. I have read:

Source:

http://www.model-engineer.co.uk/forums/postings.asp?th=28101

"I also have a granite plate from Tesco. I checked it with a GOOD straight edge (a new "best" ruler) and could not get a 1.5 thou feeler gauge under it at any point on the surface. I reckon that it is good to a thou over its surface - more than good enough for workshop use.

The smaller ones - down to "coaster" size may be useful for confined spaces!

Bizibilder"

Cool, I'm thinking I could pick one up and check it with an indicator using the EDM table at work.

I just tried this crude "zone" technique and got outlier +0.003" to -0.002" variations skating over the surface with a dial indicator....with most of it +/- 0.001"

http://www.ehow.com/how_7620766_calibrate-granite-surface-plate.html

Edited August 21, 201212 yr by Blue

IMHO flat enough for 99% of automotive work.

Excellent sleuthing Blue!

You can either spray glue various grades of sand paper to it or use this system of abrasive particles as the lapping media like these

http://www.leevalley.com/en/wood/page.aspx?p=33017&cat=1,43072

I wonder just how flat that granite really is?

From the link in the above quote: "For your convenience, we also offer a safety-glass lapping plate (8-1/2" x 14" x 1/4") that is guaranteed to be flat. "

Looks like it runs less than $14!