1. #1
    Hi there
    I am putting together a 2*5 - meter Wood Cutting router using 750 w delta Servo Motors and ASDA B2 Drivers, The Controller is Mach3 (I am attaching the Picture of it). In this Controller the Y axis is called X therefore, my 2 motors for moving the Y axis is called X1, and X2 in this controller which is no problem so far, should mention that I do not need to slave X1 to X2 or Vice versa, because they actually rotate the Motors in Opposite direction, which is cool.
    Everything was working fine, and at my first trial I moved the Motors very smoothly and nicely. I started the referencing process, and everything referenced rather nicely, and I moved to calibration Process, and everything was going fine. But at the end of the day I noticed one of my long axis, Y (which is being powered or moved by two servo Motors X1, x2) motors is lagging slightly. I thought that I should Tight up My Gantry Screws and bolts, which I did the next day, but at a little later time when I tried to reference the Axis, I noticed that My Y axis is not referencing properly, and after moving a little it stops before it reaches my Inductive Home switch, and then it continues to reference my X axis.

    After Many Trial
    My Z axis Reference properly
    My Y Axis Stops before reaching my Home switch
    My X axis Reference Properly

    Should mention that My Y axis occasionally referenced properly, but at next trial It again stopped before reaching my Home switch, and at each Trial it traveled a different distance before stopping, and as I tried more it traveled less distance before stopping. And at some Trial one of my Y axis Motors Lagged rather drastically, and a little short circuit at X1 Motor connections happened, which caused me to turn off the Machine, and re wired that connection (My X1 Motor)

    I wonder what could be the cause of it;
    1: Could it be because of my faulty cables going to Servo motor from my driver? But if I have a faulty wire or cable or the Motor itself, shouldn’t I get some warning and/or alarm coding from my Drivers? Because I do not get any alarm from my drivers
    2: The most suspicious Item to me is my Controller, I think my X1 Plugin is not working properly. Each Plugin contains 4 wires (Direction –) (Direction +) (Pulse –) (Pulse +) Line drive 5V

    Any recommendation greatly appreciated

    Regards
    Jhonansaro
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  2. #2
    Ok looks to be like your running 2 drives from one Motor Output.? This isn't good and could be the cause of your troubles. So I would sort this before looking further.

  3. #3
    Hi JAZZCNC

    Thanks a lot for your reply.

    Could you please explain? How did you figure that out? is it form the pictures that I provided? Please explain

    what is the fix for that problem?

    Regards
    jhonansaro

  4. #4
    Hi there
    Problem resolved, since I was using 2 different kind of Home Switch, apparently they created some kind of noise, that after adding some relay switches to my limit switch the problem is resolved and all is fine.

    Regards
    Jhonansaro

  5. #5
    Quote Originally Posted by jhonansaro View Post
    Hi JAZZCNC

    Thanks a lot for your reply.

    Could you please explain? How did you figure that out? is it form the pictures that I provided? Please explain

    what is the fix for that problem?

    Regards
    jhonansaro
    I figured it out because you only have 3 Motor axis enabled. The fix is easy you need to connect one of the drives to another Motor Output and then use Slaved axis.

    I see your post about different Home switches but still the way you are running the machine from one Motor Output isn't correct and will cause you troubles at some point. The problem comes from pulse timing and over long jobs then any latency in timing will have an affect on position.
    The only exception to this is if the Servo drives provide a slaving option. In this case, you will have the slaved drive connected to the master drive via a cable so will be easy to tell.

    Also the way you have it setup now then your only homing to one Switch on one side. If there is any error between the motors/screws it will never be corrected and over time this will twist and rack your gantry.
    If you had it setup to use slaved axis then you could home each side to it's own switch and be sure the gantry is square. Also because your using servos you could use the Index pulse of the encoders to ensure accurate homing of each motor.

  6. #6
    Hi jazz
    Thanks a lot for your reply, The motors are running in opposite direction right from the control board, s therefore I do not need to slave it anymore. But on the issue of second switch, sounds interesting please explain, particularly on Index pulse, how this can be done?
    Also another challenge is placing the switch itself, which must be in exact position of the other one.

    regards
    jhonansaro

  7. #7
    Quote Originally Posted by jhonansaro View Post
    Hi jazz
    Thanks a lot for your reply, The motors are running in opposite direction right from the control board, s therefore I do not need to slave it anymore.
    Think you misunderstand what slaving is about. It's nothing to do with running motors in opposite directions. It's about two separate Motor outputs working as one unit. The way you have it wired you are using just one output which is sharing it's pulses between two drives. This can lead to timing issues between those drives because cannot gaurantee they will both see pulse exactly at same time. Pulse timing is critical.
    Also like mentioned it also affects homing because only using one switch.

    Regards using the Index pulse then this depends on your Drives and if they have Index pulse output and allow Home to index feature. Most servo drives do, in this case you can tell the drives to home to index by using one of it's inputs then when at home position it turns on it's Index output which then tells controller at home location.

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