I never lock mine either. I've checked with an indicator to see if the front of the table moves relative to the head when the locks are tightened -- it doesn't. But, it has box ways and the locks clamp on the side of the ways, so I wouldn't expect the table to move even if the ways were worn. I'm pretty sure you could detect some movement on my old dovetail way Bridgeport. Perhaps relevant to this is that BP manuals point out that the table on a new machine is fitted so that the front of the table is about .0005 high.