Straightness of steel/alumunium box section

[routercnc]

If I understand the dwg in post#17, then the router plate mounting footprint onto the Y axis carraige is now very narrow. I assume the blocks with the hole in for the ballscrew are the mounting feature into the bearings and into the Y axis carraige.

If this is the case I personally would go back to you original drawing. Ross can make this work, but your geometry requirement is obviously a bit different. Don't think the bearing load would be a problem for the original dwg, especially compared to the compromise on mounting in post#17. If you keep the angle piece you can always add these to the router plate if required. Any further views on that Ross?

The supported rails do have bulk, more so than profile, so it looks like you've done all you can.

[edit: Wonder if you should allow for (i.e. drill the holes for) a second pair of bearing blocks at the lower Z support. Because of your long Z axis reach the loads will be high at the bottom bearing, trying to open it up on the post#1 dwg. Another one next to it would help. Bit like some heavy doors have 3 hinges, with 2 close together. Never tried 3 in a row - don't think there would be a tolerance problem unless someone knows different. ]