Best Z-Axis Setup

[keith1018 (Keith Wayne Medford)]

I have a question that I know is going to generate many different opinions. But here goes anyway.

What is the optimum Z-Axis setup??? I have tried the following and none seem to work exactly as designed. Currently the bed is made of 20x20 Aluminum Extrusion and has a 10inch lift height.

1st Setup was a Single motor controlling a long GT 2 belt, and a Ball Screw at all 4 corners…worked somewhat ok. But occasionally had to readjust to get back in alignment.

2nd Setup was Dual motors controlling each side of the laser. 2 Shorter belts with a belt working each side…worked ok but still had to occasionally adjust.

3rd Setup (Current) 4 Individual Motors each controlling a Ball Screw with a Bearing rod for some stability and alignment, the motors are Nema 17 Pancake motors with a single controller. Each mounted at a corner of the Laser Bed. Down side is that the motors can and do get yout of SYNC, and it can and does cause some issues. Especially since there is only 1 Switch for bed leveling. But, it works ok, so far, just implemented this design.

5th Potential design if the above does not prove sufficient is to replace with possible Nema 23 Motors, bigger Ball Screws, and better support rod, to include using 4 separate Controllers linked to the Ruida DSP Controller. Just not sure how this setup would function, as with all of the above setups.

6th Potential Design will be getting 4 small Scissor Jack, and link them together with a Pinion Gear and have 2 on each motor.

Just trying to find the best solution to a common issue with home built Machines, especially large and truly custom ones.

Keith M

[ednisley]

@keith1018

Single motor controlling a long GT 2 belt, and a Ball Screw at all 4 corners

That’s basically the setup in my OMTech 60 W machine:

The hulking NEMA 34 stepper motor (on the left) drives a continuous 15 mm wide belt around the four leadscrews at the platform corners.

Each leadscrew has an upper bearing, but they seem to be sufficiently warped that the platform moves in a gentle 1 mm circle as they rotate, so hitting precise XY locations at different heights doesn’t work well.

Because the Ruida controller cannot home more than a single motor, using one motor with sufficient mojo to raise the platform seems more practical than hacking anything with multiple motors. That motor will require a much wider belt / pulleys than the skinny ones found in small lasers & 3D printers, plus dramatically higher belt tension to avoid skipping (even without debris in the teeth):

Show us pictures, because we loves us some homebrew laser action around here!