I am in the middle of a build and I am having trouble with the extrusions..... I have ordered 10 and 15 series T-slot aluminum extrusions from a place called automation4less several times over the years. This last time has been a big enough problem that I will never return nor can I recommend them ever again. I will just cut to the chase here and describe the problem and am hoping that you guys can help me get it rectified.

The "frame" of my table is made out of 15 series 3" square t-slot extrusions running horizontally connecting plate aluminum on the sides where the linear guides will mount. I noticed an issue with the extrusions prior to assembly that is now creating a major issue. The cuts on the extrusions are not square. They taper off .017" and worse from what I have found so far, This is causing an issue when I tighten down on the screws that attach the side plates to the extrusions. It is causing the plates to warp and in turn causing the linear guides to warp and making the bearing blocks run rough in some areas. When I loosen the bolts the bearing blocks run like butter on a hot skillet. I thought to myself that I would just line them all up and have the out of square portions all run the same way. When I do this, the other ends have the issue running in opposite directions. I have room to give on the length of these. Basically I need to find a way to accurately square up the ends of these pieces.... Any suggestions?