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please advise on motor kit for ox router.

Discussion in 'Motors' started by Ophis, Jun 7, 2015.

  1. Ophis

    Ophis Well-Known
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    Hi everyone, I am planning on building an ox router soon and am about to start buying parts.
    i am still unsure on what electronics I am going to go with, mainly because of motor torque.

    here is the link for the motor and driver kit I have been considering purchasing.

    http://www.ebay.co.uk/itm/Germany-S...201?pt=LH_DefaultDomain_3&hash=item3f3849dc09

    my first thought is the nema 23's in this kit are 425oz where as i notice the original ox only uses 175oz motors.
    will 425oz be to much torgue? they dont seem to offer any lower torque with the same drivers.

    i know most people would say get a gecko 540 but that alone is about £300 and my budget for the entire machine is £1000 and i dont really like the idea of an all in one board as I know if a wire pops out while the machine is on the driver chips let out their magic smoke.
    i have also read that the leadshine dm542 drivers actually out perform the gecko 540 and that the longs motor dm542a drivers are identical to the leadshine ones if not just rebranded versions of them.

    this kit has 2 power supplys that run at 36v with 9.7amps each so that should be plenty even if all 4 motors are running at once.

    i know the chinese stuff gets a bad rep from the tb6560 drivers that could only put out 30% of their rated current. the seller from the abouve link has 100% feedback with alot of sales so i would guess there must be something good about the longs motor stuff.

    i plan on using linuxcnc with this on an old athlon 2600 mobo, it has usb boot capabilitys so hopefully i can run it barebones inside my controll box and operate the thing remotely over the network.
    for cam software i quite like heekscad so far.
     
  2. Joe Santarsiero

    Joe Santarsiero OB addict
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    It looks like that kit has all you'll need. As long as your mobo has a db25. You can download mach3 and get started. I think there are a couple of others here that have that bob. Rick 2.0 might be one of them if my memory serves me.
    Torque isn't a problem. If you're really concerned then use flexible motor couplings. That way, if you hit anything they have a better chance of snapping instead of twisting something else. You should see if you can find the motor torque curves to check them against the speeds and feed rates you'll be using. Also, I only glanced at that package, but it looked like the drivers can handle 50v. See if they'll upgrade those 36 volters to 48v or what the max output is for the 36ers. Aim for giving the drivers 45v. This will give you the most bang for your buck while protecting the drivers from back emf in the case of estops. If they won't do 48v. then you should be good with the 36. otherwise, the stepper specs are pretty reasonable. Are those drives leadshine knock offs though?
     
  3. Ophis

    Ophis Well-Known
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    hi joe ty for your reply.
    I ended up ordering something different in the end i went for this kit for £138
    http://www.ebay.co.uk/itm/Free-Ship...489?pt=LH_DefaultDomain_3&hash=item233e3fd2d1

    i noticed on the other kit i was looking at the motor shafts were 8mm and no one seems to sell the gt3 pullys with 8mm bore, 8mm to 8mm flexible shafts seem on the rare side too.
    i figured since it was £107 pound cheeper i could buy some new drivers eventually to replace the dreaded tb6560ahq board that came with it, ive seen the long motors dm542 ones sell for about £70 for 4 with a db25 board thrown in.

    the motors are 270oz 23HS8430 and it also came with a single 24v 15amp psu.

    Been having a play with it and set it up with mach3 initially just so i could follow the instructions that came with it, but now have it working on linuxcnc which was abit harder to do, is alot easier to slave a motor to another in mach3, the board uses 3 amplifier enables to drive 4 motors so i got abit confused with that for the linuxcnc settings. all seems to be working now tho, and it seems to sing nice songs when its following the sample linuxcnc lettering.

    am little stuck on the timings for step time, step hold, direction hold and direction setup. wiki.linuxcnc.org says 150,000 for all values but linux cnc will only go up to 100,000. i have tested out a few other settings that ive seen around the internet, it seems to work no matter what i throw at it. im not really sure what im looking for to improve these settings.


    ive tested diffrent dip switch configurations, i notice anything other than fast decay produces horrible squeeling, i have it on 1/2 stepping atm at 50% current have tried 1/8 and 1/16 and i notice it slows down alot in these modes. ive not used more than 75% current as i figured the drivers are rated for 3.5 amps and the motors are 3 amps. i guess it will be more usefull to play with these settings when i have them attached to a machine and i can better see what effect they have on it. If i do end up replacing the board i will most likely go for the gecko g540 after all, more for the readily available information available on settings than anything else.

    got some ox plates off ebay, so time to order millions of extreme solid v wheels, fittings and extrusions.
     
    Joe Santarsiero likes this.
  4. Joe Santarsiero

    Joe Santarsiero OB addict
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    Hey Ophis, congrats on the buy. Good catch on the shaft size. That might've been a headache later! That board will get you by for now. At least you can go further on learning the controller and cad/cam side of your process. I can't comment to much on linuxcnc as I haven't used it. I do know the 6560s need a long pulse width. The tb6560 datasheet should help some regarding pulse width and timings. It won't account for any other delays caused by other board components though.
    Also, in mach3 there is a sherline mode that lengthens the widths considerably. I've read a few posts of others with tb6560s using it.
    Switching between step settings requires software and sometimes hardware changes. The motors should move at the same speeds if everything is set correctly. The major differences are in smoothness and torque. When the time comes, stick with 1, 1/2, or 1/8 if you seem to be getting away with it.
    Here is a good read on microstepping:
    http://www.micromo.com/microstepping-myths-and-realities

    The gecko will treat you right when the time comes and this cheap board should enable you to be ready for it when it arrives.

    enjoy

    Joe
     

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