Sorry for the long radio silence, things have been quite busy here and I could barely find the time to work on this.

I took the advice with the Y-Axis Ballscrew and the Z-Axis sleds to heart and changed the corresponding geometry:
Click image for larger version.  Name: NewZ.PNG  Views: 3012  Size: 219.0 KB  ID: 25776

On the to-do-list are the following things:
  • Add a mounting point for the Z-Axis NEMA 34 behind where the Y-Axis ballscrew currently connects to the Y-Axis sled.
  • Add an "Omega-Drive" belt structure to the front to run the two X-Axis Ballscrews from one NEMA 34 stepper. The "Omega-Drive" structure is there to maximize surface contact between Belt and Gears
  • Finally add that back ballscrew-bearing plate to connect it to the base structure
  • Add a Spot for the Y-Axis Motor to sit. Due to clearence with the Y-Axis sled I am still unsure where to put that, but maybe even below the X-Axis rails on the bottom?

Do any of these plans throw up a red flag from something I have not considered yet?

I have also been talking to the mechanical engineers in my workplace, who came up with a plethora of ideas to alter the design, so I am seeking a second opinion on some of these:
  • Substitute the Aluminium Profile for Steel Box section and weld it. The warping should be controllable in a machine this size, is what I am hearing.
  • Change the Y-Axis gantry to a design that has a Profile up top and one below with the ballscrew sandwiched in between. The rails would go to the front and both profiles would be held together at the sides, like they are now, and with an extra plate at the back. Alternatively manufacture this out of steel section.
  • And now to the weirdest one to me: Mount the gantry to the X-Axis like it is now, but only on one side. Then have the other side be out of thin steel with only a loose connection to the gantry beam, thus only inhibiting rotation, but not translation. This would "solve" the problem of the gantry being over-constrained, since the second beam would only brace against torque, but allow the gantry to move over it, in case the rails are not exactly parallel. I know that in theory this makes sense, but it still seems counter-intuitive to me in terms of rigidity.


In the mean time I will work on getting the steps on my to-do list done and report back once I am done with that!