Y and Z Axes Version 3
Posted by retromaster on February 8, 2010
Here are the final versions of Y and Z axes of my CNC-converted MF70. The Z axis end-plate consists of two 5mm thick aluminum plates bolted back-to-back. One ball bearing is mounted in each plate, held in place together with the tightened nylon-insert nuts on the leadscrew. To clear the ball bearing on the bottom side I had to raise the end-plate using two nuts as spacers (not shown in the photo). I’ve also replaced the coupling with the new flexible one. It looks and performs considerably better than the previous version.
In the previous version, the Y axis leadscrew was supported at both ends. Instead, I decided to switch to a single side support scheme similar to the Z axis. This has the advantage that, on the other end, the carriage can move all the way to the Z axis column. I had to mill a new standoff for the end-plate in order to make room for the second ball bearing. This standoff is screwed to the lower table base to make it sit perfectly flat. To make sure that the single side support does not cause an issue, I’ve also built a new delrin nut that is a bit taller one one side than the original one, so that it tightly sits and slides on the lower aluminum base of the table, creating kind of an additional support. Overall, this new version of the Y axis is a very good performer and the travel has been extended to around 92mm, effectively doubling the stock MF70 travel.
For the moment, minor corrections and improvements aside, I consider the machine complete. In the future, perhaps I may switch to higher torque motors and more sophisticated drivers to improve on speed and smoothness. My intention now is to put together a project page to document the final state of the machine and provide some technical information, schematics, drawings, etc.