As of now, the stock screws on the ZTW 7×12 kit aren’t particularly fast, but there is an upgrade involving a new “F8” leadscrew that I’ve done for the X-axis (my article about it) that makes the router travel 6.4 times faster – seriously. This video should explain what is involved when making the upgrade, but I’ve jotted down some notes afterwards.
As seen in the video, you’ll have to take the bottom support apart and detach both the guide rods and the original lead screw. Once this is done, you may need to lift the axis attachment up or remove the motor to avoid pulling on the wires too much.
With the gantry assembly detached, unscrew the anti-backlash assembly from the gantry, then roll the lead screw off of it. Save the screws and nuts as you’ll use them with the new one, then screw everything back together inside the gantry. If you screw the anti-backlash assembly on outside, it won’t fit, but you’ll realize that as soon as you do it. Reattach everything and you should be good to go mechanically.
When this is done, don’t forget to adjust your “motor tuning” to take advantage of your new Z-axis speed. The motor steps per unit in inches should be 5080 and the maximum velocity and acceleration can be set at 100 or lower (possibly slightly higher too) For most people, the Z-axis would probably be the least important axis to upgrade, but for my light painting experiments, it should speed things up very significantly. For comparison, watch the video above then see the video in one of my early light painting posts. Really an incredible difference.