[RealManBearPig]

Hello!

Electrical engineer here playing as a mechanical. I am in the process of designing a moving gantry CNC router. Currently, I am working on finalizing the Z axis design so I can get an idea of where the gantry's center of rotation will be with everything attached.

Z axis travel will be 170mm max
2.2kw 80mm spindle
Aluminum plates are 1/2" thick with vertical 1/4"x5/8" pieces added for rigidity (may change to steel to get the spindle closer to the gantry)
HGH15ca linear rails with dual carriages
SFU1610 Ball Screw (May change to 1210 if I can find a nice ground one on ebay)

I am using fusion 360 and unfortunately the FEA simulation is no longer included in the maker version (May bite the bullet soon and subscribe to the full version). In the mean time, I'd like some opinions on which of the following would be the most rigid for the spindle plate


Option 1: Spindle mount does not extend past linear rail carriages and is mounted high up on the spindle
Option 2: Spindle mount is halfway on/off the rail carriages and mounts in the middle of the spindle.
Option 3: Spindle mount is completely below the linear rail carriages and mounted towards the bottom of the spindle.

All three options have vertical "stiffeners" attached to the back of the motor plate although without the FEA I'm unsure how much rigidity they're actually adding.