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  1. #31
    Hi Jonathan..

    I had always thought bipolar series was preferred to get the higher speeds? Is parallel better?

    Steve..

  2. #32
    Quote Originally Posted by fasteddy View Post
    I had always thought bipolar series was preferred to get the higher speeds? Is parallel better?
    Yes parallel is generally faster. Bear in mind the current the drivers is set to also makes a difference as the torque is roughly proportional to the current (until you go much above the rated current and the rotor saturates). If the nearest current setting to the current in series is greater than the parallel setting then it may not make much difference. Karl has the motors on 2.37A, and the rating is 2.1A so it's already 13% over. The PM542 maximum is 4.2A, so the same as the motors ... so if putting in parallel gains less than 13% then you may not gain anything though it would be nicer. There's more to it than that though... in the end it's easiest to just try it and see. Keep an eye on the motor temperature too.

  3. #33
    Quote Originally Posted by Jonathan View Post
    You and Steve are both running these motors in Bipolar series, not parallel ... interesting.
    If so then it's very likely your way under voltage and just simply running out of torque, the torque drops off very quickly when wired series.!#

  4. #34
    Quote Originally Posted by JAZZCNC View Post
    If so then it's very likely your way under voltage and just simply running out of torque, the torque drops off very quickly when wired series.!#
    However, for completeness, the torque when wired in bipolar series is greater at low speed than the same motor wired in parallel.

    It looks like in Steve's case it's the Y/Z axis motors that are in series, and they're not at fault. Still worth trying, as long as the power supply can take it.

  5. #35
    Quote Originally Posted by Jonathan View Post
    However, for completeness, the torque when wired in bipolar series is greater at low speed than the same motor wired in parallel.

    It looks like in Steve's case it's the Y/Z axis motors that are in series, and they're not at fault. Still worth trying, as long as the power supply can take it.
    Yep exactly, thou as the speed rises the torque drops away very quick in series and because the X axis needs the most torque due to it's mass and it's happening when rapiding I'd be changing to parallel.

    Edit: That said I still don't think this is Steves problem due to him having the problem at lower speeds.?????

  6. Just taken some motor current measurements on my machine - measured at the output of the star-wired PSU:

    - Powered up but stationary the 3 drivers and motors together pull 0.87A (DC) total. Motors bipolar series. Driver PM542 settings now 2A (RMS) limited.
    - MACH3 jogging X,Y or Z axis individually pulls 1.36A during acceleration levelling at 1.25A - this is the machine's full MACH3 limited speed of 400mm/min.

    Jogging in, say, X and then also jogging Y - ie causing the horrible mechanical noises and poor movement - pulls 1.6A to 1.9A total.

    Jogging the Z full speed and then - at the same time - jogging either the X or Y in any direction does not cause any problem (likewise moving either X or Y and then engaging Z causes no problem).

    My PSU is rated at (43V) 5+ amps so, given the figures above, current does not seemed to be an issue.

    I'm wondering if this problem is due to inertia/momentum/twisting forces in the, not very expensive, X-Y table?

  7. #37
    Hi Jazz..

    Just a quick mention that I am only getting this problem when the X and y are at maximum speed...

    Steve..

  8. #38
    Have now re-installed Mach - no difference..
    Also tried another PC, although it is a pretty low spec laptop (setup as a standard PC) - no difference..
    Going to rewire my nema 23's (3Nm) in bipolar parallel today, not sure if I will be able to do the same with my Nema 34's as they are 4 wire motors, just waiting on a bit of advice on that, unless someone out there knows how to do it?

    Just want to say that although I have not got to the bottom of this problem yet (and neither has Karl, my sympathies dude), I am very grateful for all the advice given.. Checking so many aspects of my machine is a real confidence booster with the level of scrutiny it has had this week, I feel like several engineers have checked my work and so far, most of what I have done seems right and a couple of things I have been able to improve..

    Steve..

  9. you cant connect a 4 wire motor in parallel, it is similar performance wise as if you had an 8 wire motor connected in parallel.
    Out of interest does this problem happen if you disconnect the ballnuts from their mounts?
    Also does the X axis stall when the Y axis is in a specific position or is it random?
    My thinking is that is may be a mechanical problem with the stiffness of your machine?

  10. #40
    Still happens with the ballnuts disconnected, I had removed the ballnuts last week and cleaned them out, then tested that principle as I was originally thinking along the same lines.. The problem can happen at any position on the bed (2mt x 1.4mt) although it seems to happen much more on moving the x axis +, rather than -..
    Mechanically, the machine is sound and I have torn apart and rebuilt it twice in the last week, everything is freely moving..

    If I get a chance, I will make a little video of it happening later today..

    Steve..

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