I have read a few past posts about putting them on a flat steel table or a peice of glass or a steel ruler? thanks

 

Yep...a piece of glass is flat enough. Then use shim stock, or feeler gauge to check the size of the gaps.

 

what is the max they can be? my cdrom says that the steel driven maximun warpage should fall through a slot of 1.63mm (.064 in.) what the hell does that mean? thanks again fellers

 

Measure the plate thickness. With a mic if you have one. Subtract that measurement from .064. The remainder is the tolerance. Actually its about 1/2 that much, because if you can get .005 " under the glass from one side, the other side is up .005.
So if the plate measures .054, then .064 minus .054 = .010", which means you can be warped .005 per side.