Router design thoughts

[m_c]

I've been thinking about it some more, and just skecthed both options.

Fixed bearings
+) Shorter rails. With fixed rails, ideally you need the bearings mounted at the extremes to avoid the working area overhanging the bearings, so you ideally need the rails extending the axis travel past the end of the work area. With fixed bearings, the bearings can be positioned closer together, as the supported area will always remain below the spindle, off course depending on how the table is loaded, it could lead to it bowing.

Fixed rails
+) Lighter table. 4 bearing blocks are far lighter than two rails.



I'm still undecided between fixed v. moving gantry.
I can see the pros and cons of both, but I'm currently swaying towards moving as it means a relatively constant moving weight (moving table means I'd have to tune for it potentially having a lot of weight mounted on it) and it gives me a bit extra flexibility for table loading (could work with longer length materials with less precutting required). Available space isn't a major concern

[Robin Hewitt]

Fixed rails
(+) Lighter table. 4 bearing blocks are far lighter than two rails.

Surely a lighter table is a minus. Vibration is the enemy and dead weight dampens vibration.

Same goes for the gantry, bolting it to a dead weight reduces the rattle.

Power to move a heavy table/workpiece ceases to be a problem the moment you start using ball screws. You get an enormous push.