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  1. #11
    Quote Originally Posted by John S View Post
    so it it defaults on one axis whilst cutting and trips you wreck the job ?
    No, surprisingly enough, so long as it doesn't expire on a G0, they've thought of that :naughty:

    It tells you before it fails so you can stop everyone, then powers up to the same phase settings it was on when it failed.

  2. #12
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    I've wondered about this too. We buy motors based on charts and curves, but the manufacturers don't declare anything of the test method.
    How tricky would it be to build a simple test rig? Budget ~100?

    Stepper -> direct coupling -> load
    The load could be something like a motor with variable resistance across it.

    I'm thinking: set a stepper, drive, and power supply combo running at a known RPM from mach or EMC2. Measure the voltage and current through the load, gradually increasing the load (by removing resistors in small steps), until the stepper stalls. Plot the data point, then increase the RPM and repeat.

    Obviously the results would only be valid for the stepper/driver/power supply combination tested. And the results between different test rigs (if more than one were built) would not necessarily be directly comparable because of efficiency differences of the load motors. It would allow you to check the effect of a power supply voltage increase, or a new motor type, or a new driver, or moving to microstepping, or etc etc etc...

    How much work is there to get to the point where the results might be comparable between rigs? Would defining a "standard" dc motor type be good enough (eg choose an appropriate RC motor P/N from a popular manufacturer)?

    Just thinking out loud...

  3. #13
    Tom,
    Good idea but still relies on "Is the motor in the box the same one the spec sheet is for ? "

    And to be honest working with the Chinese I'm very sceptical.
    Out of a box of 40 rotary tables that all had the exact same run out error according to the spec sheet? every one ?
    John S -

  4. #14
    Quote Originally Posted by Robin Hewitt View Post
    No, surprisingly enough, so long as it doesn't expire on a G0, they've thought of that :naughty:

    It tells you before it fails so you can stop everyone, then powers up to the same phase settings it was on when it failed.
    So that relies on you being there ?
    Not a lot of use to me then, My big CNC is running all day today, last half hour I've been down Asda buying a new kettle but it's still churning out parts.

    .
    John S -

  5. If you measure the torque directly it doesn't matter what type of load.

    a simple way to measure torque is to use two indexing discs (opto or magnetic pick-up) separated by a torsion spring (a thin rod or shaft). By measuring the timing difference between the indexes one can calculate the angular displacement thus the torque (the torsion rod can be calibrated statically with a simple arm and weight).

  6. #16
    Quote Originally Posted by John S View Post
    So that relies on you being there ?
    No more than you have to be there to turn the handles, computers can handle fault conditions.

    I can see you aren't impressed :rofl:

  7. #17
    Tom's Avatar
    Location unknown. Last Activity: 30-11-2016 Has been a member for 7-8 years. Has a total post count of 172. Referred 1 members to the community.
    relies on "Is the motor in the box the same one the spec sheet is for ? "
    I agree - this can be a bit of a lottery. Sales literature sometimes gets pegged to a P/N for a good while longer than the engineer who wrote the data would be happy with. Hopefully though it means you get something better than on the spec sheet, rather than worse. (hopefully).


    a simple way to measure torque is to use two indexing discs (opto or magnetic pick-up) separated by a torsion spring (a thin rod or shaft). By measuring the timing difference between the indexes one can calculate the angular displacement thus the torque (the torsion rod can be calibrated statically with a simple arm and weight).
    Bill that's a much more robust way of doing things. The index disc on the stepper side could also be used to check for missing steps before the stall. It's probably even possible to use a couple of parallel port inputs to feed into the halscope in EMC2 to take the readings...
    Hmm I can feel a project coming on before I build machine number2!

  8. #18
    Quote Originally Posted by BillTodd View Post
    a simple way to measure torque is to use two indexing discs (opto or magnetic pick-up) separated by a torsion spring (a thin rod or shaft).
    Do we really need brake horse power? Couldn't you just wrap a bit of string round the pulley, tie it to a spring then see how far it gets before it stalls?

    You could then calibrate the spring by tying it to a horse :naughty:

  9. The 2M2280n is a new driver that replaced the leadshine driver that everyone is familiar with (M2280) The M2280 stated 220V but in reality if you supplied it with 220V AC over a long period of time the driver would fail.
    the new 2m2280n, is way better than the leadshine driver and is totally different, with a lot of new features that until recently you would only find of very expensive drivers.

    It still only rectified the AC, so will not work with smaller motors, and is really only good for the largest 34 and 42 frame motors, and the downside is the heat, but if you are using good quality motors, you will be ok
    When i worked at MCP we have a lot of the M2280 drivers back from customers connecting them direct online.
    Even though the motors got hot, no motors were returned after failure, this is because we used quality motors.
    There are a lot of motor manufactures in china and most started when a large state owned factory changed and a lot of the engineers decided to start out by themselves.
    There are four manufactures in china that i would be happy working with, and the others i either have no experience of or would not touch them with a barge pole.
    I have been working with Chinese motor manufactures for nearly 15 years and started off with the large state owned factory (GBM).
    The problem is that a lot of so called motor manufactures are not actually manufactures and are only agents and the problems of getting the motor you ordered becomes a problem, because they shop about for better prices and motors on one order will be different on the next so that is why you need to work with a factory that is ISO 9001 and produce motors that are CE or UL.
    There are not a lot of those.
    If you have continuity problems with the motors you are currently buying then you are buying from an agent or a factory with no quality control, and need to change.

    The ISM6045 is 5V only.

    Someone asked about encoders, we have solid shaft encoders in stock, but have not had the chance to put them on our site so if you know what you need tell me and on Monday i can check stock and tell you the price.

    We also have hollow shafted encoders but not as many.

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