PCB Isolation Routing
Mk I (smasher)
Motors and controller
All axis are driven by M8 threaded rod and delrin drive nuts. M8 rod has a 1.25mm pitch so it is very slow. However, on the plus side it has acres of torque.
A very simple anti backlash arrangement was set up by placing a couple of springs on the bolts that mount the drive nuts. Tightening the drive nuts by different amounts causes the drive nut to twist relative to the rod, thus taking up any backlash and wear. It's not perfect but fairly simple and quite effective.
The X and Z axis are coupled to the motor directly via an oldham coupler.
I am using 2 screws on the Y axis, so these are coupled together via a long T2.5 16mm wide, 1300 pitch toothed belt and pulleys. On hindsite, HTD3 or 5 would have been a better choice.
I am very impressed with the twin screw arrangement. I'm sure it helps with the rigidity and accuracy of the dubious Y axis bearing design. As an added bonus, it frees up the underneath of the machine. This makes it much easier to mount say a rotary axis underneath the work area or the work on larger material by poking it up under the router.