When grinding especially heat is a real problem. If your grinding a flat piece heat is the ultimate enemy. And if your grinding round stuff on a spinner all day the bearings make heat, causing the centerline to grow and shrink.
Here's the best damn heat sink you can have on the planet. Take a heat sink from an old computer. pentium 2 chips were the largest and had huge heat sinks on them. Aluminum rocks, but copper is even better. Take the heat sink and cbore 2 holes in opposite corners and glue "wire edm" magnets in them slightly below the surface. I'm telling you guys it will suck the heat out of a block in seconds. If using it on a spinner for round work, place the heat sink on the back where the bearings are, obviously point the ribs up because heat rises. you will keep the spinner ice cold making it repeat to within a tenth all day. Normally when you grind a bunch of parts you use your surface plate as a heat sink, moving the parts around the plate as you rough them out cooling them down. Add the heat sink in the pile and it will cool your surface plate down also.
If you need a quick chill down, blow some air thru the ribs and it will cool on steroids.