Retromaster’s Electronics Projects

…related to old computers and other assorted stuff…

MF70 CNC New Drive & Motors

Posted by retromaster on April 11, 2011

Here is the new motor driver installed and working with the new steppers. It is the infamous 3-Axis TB6560 Chinese driver commonly found on ebay. I could have designed and built my own, but the price was too attractive to pass up. The board supports 1/16 microstepping and 3.5A per channel @ up-to 36V supply. Combined with the new motors (Minebea/Astrosyn, apparently salvaged from Diebold ATMs) the speeds have more than doubled-up, at slightly more than 200mm/s.

The enclosure (from a local supplier) is of good quality, but ultimately an overkill, and it is a bit too large for this board. Unfortunately, the nearest size in the manufacturer’s catalog was just a couple of centimeters smaller than the board.

Despite all that looks good on paper, I have to be wary of recommending this driver board, because mine turned out to be defective! Upon testing, I found out that the Y-axis was not providing enough torque. Some inspection with a multimeter revealed that the DIP-switch for the Y-axis was broken, resulting in the current setting being ignored. The fix was easy, with just a couple of wires, as in the photo above. Nevertheless, this just seems like another example of fine (!) Chinese manufacturing on display.

5 Responses to “MF70 CNC New Drive & Motors”

  1. What really went wrong with the plastic parts? Breakage?

    I too am interested in this TB6560 driver board. As you say, the price is tempting, but the reviews all over the internet says nay… Just can’t see how a manufacturer that makes these boards have not yet come up with an improved version.

  2. retromaster said

    Well, the plastic parts flexed too much (I wish I had taken some photos). I later remembered that the original plastic parts on the MF70 were backed by some sheet metal inside (and still they did not have to support a heavy stepper motor) so this result is perhaps not so surprising.

    My TB6560 driver board seems to be working fine so far… But do expect problems if you get one. Apart from the problem I described in the post, there is also the issue of high-pitched noise emanating from the steppers. Frankly, though, I am not sure if this is due to the driver board itself or EMC2, but I need to check with the oscilloscope to find the source of this noise.

    In the end, the board I have works… But the bottom line is, it’s a gamble, and be prepared to pick the soldering iron up if you buy one.

  3. Simon said

    I realized I have a Proxxon mill I hardly ever used, and this has inspired me to want to convert it.
    I have a couple of questions.
    1) Did you replace the lead screws? I guess I might have to as I don’t seem to be able to remove the screw holding the handles on, and the top handle appears to be riveted and not screwed at all.
    2) Do you know what torque you are using on your motors? I want to make sure I get a motor that is sufficient.

    Thanks

  4. retromaster said

    Simon,
    I did replace the lead screws. But it is possible to remove the handles, they are held in place by rolled pins. Please see here: http://www.indoor.flyer.co.uk/millingmachine.htm
    I cannot tell you the torque ratings for the motors because I do not know, they were salvaged from other equipment.
    -RM

  5. Simon said

    Thanks for the quick response. I had one last question (and a request!)
    Are you using any sort of limit switches, as I don’t see any mounted on the machine? (i.e. to stop the machine from trying to keep running when at the limit of one of the machine’s axis travel).

    And the request, I tried to download the Parallel Port breakout.zip and it says that it has been removed.
    Did I miss something here, if there is a reason why you removed it? If not is it possible to upload it again?
    Thanks so much.

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