My second router design

[Ross77]

I'm just in the process of doing a post to explain the reasons why the rails work better that way. Looking at the Thompson guidance the load capacity is reduced by a quarter if the force is pulling the bearings away from the rail. whilst you probably wont exceed the max. load of the bearing it is the rigidity that is important.


Nice touch adding the wrap around z axis carrier, should be rock solid. I noticed on the Thompson site that they use a small bolt to squeeze the open ends onto the rail to pre-load them and remove any clearance to further stiffen the carriage. you could easily add this if needed ( note only very small amount and does mean the rails must be perfectly aligned as the factory clearance is to over come minor rail alignment problems.)

With regard to the the red sections I would stick with ali as you will then be able to have decent tapped threads for the rail mounts and backing plate. Normally solid bars are not the most efficient way of making beams as the centre part offers little in the way of torsional and bending resistance (parallel axis theory), but as you want a solid machine for Ali then the extra weight will help damp out vibrations. if you went for steel I would go for box section to reduce weight but these are known to 'ring' as certain frequencies, add the need to grind and its probably best to go for the Ali bar.

I would still be tempted to widen the y axis to create a squarer beam, as this will improve the torsion resistance when the cutter is in he middle of the beam. you could just add some angle to the back plate.

Again just my opinion, not saying you have to do it this way.