My machine is made with 8080 extrusions for the long axis. One of the "features" of 8080 extrusion is something called the "Drop Lock" which can be seen here: 80/20 Inc. - The Industrial Erector Set?
The problem I'm having is that when I bolt down my t-slot extrusion table to my 8020 extrusions, the middle of my table raises about .008 and the ends drop about .003 for a total "bow" of the middle being about .010 higher than the ends. This happens with just the smallest amount of pressure at the ends. I Didn't measure but it's probably even worse when both screws at each end are tightened down. I'm thinking that this is due to the drop lock feature.
I've checked the table extrusion and it's very flat when it's not being bolted down at the ends. just barely tightening it down to the extrusions it's still flat. By barely, I mean when you take up the slack and the screw just touches the metal. Anything beyond that (like an 1/8th turn) and the middle starts to bow. when the middle is at +.008", the screws are still loose enough to move the table top easily.
This is a problem. Any suggestions on what could be done to remedy this?