Granite Surface Plates For A Hobbyist's Shop

[verbotenwhisky]

Deluxe Stone Slab the largest I see now is 12"x12".

 

[Dabbler]

For a possible cheap but generic surface plate, is there any Granite countertop places around you. I have a couple drops from my local place that I use. It’s scary how many big pieces they throw away.

The places around here sell leftovers, but using a repeat-o-meter shows that they have dips and mountains +/- .005 all over the face. A friend of mine tried 3 of them - before he bought a busy bee surface plate, 12X18". Even from offshore it was sub tenths on the repeat-o-meter.

My wifey bought a piece of granite 16"x16"x 1.25"thk from Tandy Leather products for 40 bucks, they sell these for folks to use on a table when they are working with leather shaping tools.

well, then it was a GREAT deal!!! congrats!

 

[Nctox]

The places around here sell leftovers, but using a repeat-o-meter shows that they have dips and mountains +/- .005 all over the face. A friend of mine tried 3 of them - before he bought a busy bee surface plate, 12X18". Even from offshore it was sub tenths on the repeat-o-meter.


well, then it was a GREAT deal!!! congrats!

I'm gonna really sound like a novice, which I am, but I remembered a slab of granite cut out for our kitchen sink when the house was built 20 years ago. I dug it out from behind stuff in the basement and am using it with my new to me height gauge. I'm new even to the class of hobby machinist, so my projects may suffer from imprecision, but at least I have something to start.

 

[Dabbler]

@Nctox the granite counter top cutout will be accurate to about .003, which is the thickness of a piece of paper.If you grab float glass, teh thickest you can buy and cover the granite, you will end up with a surface with a local flatness of .0005 or better, and an overal flatness of around .002. This is because the galass will average out much of the polishing holes.

We found the Busy bee (sort of Canadian Harbour Freight) surface plates (about 65$ Canadian pesos) is good to .0004 or .0003. this is more than good enough for hobby work in general.

 

[rwdenney]

For US customers, Woodcraft sells a granite plate that is at least shop-grade, 12x18x3”, for $120. It’s Chinese, and the claim of local flatness of 50 millionths is probably a joke, but mine is within a couple of tenths. I use mine a lot for layout, checking my own accuracy and precision assembly. I think it’s the sweet spot for hobbyist use.

Rick “good enough is good enough” Denney