Retromaster’s Electronics Projects

…related to old computers and other assorted stuff…

MF70 CNC New Y Axis

Posted by retromaster on December 28, 2009

Here are a couple of photos showing the new parts for the new Y axis installed. The speed has been improved by a factor of at least 3. This is with the existing stepper control board drives based on the ULN2003. With the planned new bipolar stepper drives,  the speed should increase even more. This said, however, the new Y axis is far from perfect. The motor swings up and down while the axis is in motion.  I am guessing that this is due to the imperfect motor-screw coupling, and perhaps also because of the extension standoffs that I’ve milled for extending the travel of the Y axis. While the Y travel has been extended successfully, it seems that the standoffs do not sit very well on the face of the Y axis slide, therefore the endplates are not at a perfect right angle.

It seems that the speed increase may have resulted partly from the motor mount screws (only 2 as opposed to previously 4) acting as a flexible coupling, compensating for the rigidity of the actual couplings. Although these problems prevent the machine from reaching its true potential, it still performs acceptably, and for this reason I’ve gone on to build parts for the X axis. Once the new X axis is complete, I’ll be able to mill parts much more quickly and build the new parts (such as new couplings or standoffs) needed for fixing the imperfections in the machine.


2 Responses to “MF70 CNC New Y Axis”

  1. Ron said

    Did you use any special type of bearing for the lead screw support? I would thing there is too much ‘play’ in a regular ball bearing. Also is the other end done the same way? Did you make your own coupler?

  2. retromaster said

    I used just regular bearings. The ones I used do not seem to have any noticeable play, although it is possible that there is still some there. Both ends are done the same way. As I said, the new Y axis is far from perfect but it is still a significant improvement compared to what I had before (and what the stock MF70 has). I made my own coupler, and that’s partly why it’s not perfect either 🙂 I am steadily improving this machine, using the machine itself 🙂

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