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Thread: Wiring help....

  1. #1
    Join Date
    Apr 2007
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    Victoria
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    Default Wiring help....

    Building my first machine but need a little help with the wiring side of it...

    I'm using the gecko 540 with nema 23 387 motors and a 7.3A 48v power supply.

    Do I need to run resistors in my DB9 connectors for this setup ? Motors draw 3.5A, Inductance of 2.8mH. I'm a little confused as the gecko manual states if your motor draws 3.5A or above you dont need a resistor and can safely run it but the 540 wont go into current standby mode which will result in increased motor heating.

    When using sheilded cable for wiring the motors, at the motor end are you required to connect the braiding to the motor housing and or frame. (Table frame is all alluminum) ?

    They probably sound like very basic questions but I dont want to damage the controller due to a simple wiring issue.

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  3. #2
    Join Date
    Feb 2008
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    Australia
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    You can run it without a resistor but then when the motors are ideling it wont cut the current to 70%.

    Basically you lose that feature if you dont use a resistor.


    IMO it doesnt matter if you shield it to the motor or machine, the housing of the stepper motors are also made of cast aluminium, personally I use the mounting bolts of the motor to attach my ground.

  4. #3
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    Agree with the above post. With the grounding just make sure you don't use the braid to ground on both ends. I would personally use the control box (if conductive) or something in the control box as the ground bar and having the ground location tied into the earth of the mains power for two reasons. One its logical to then run grounds out from the box, thus reducing the tendency to create ground loops. Secondly, if you ground to the motor side only and run no other ground, you have an isolated ground (ie. not drained anywhere) and if by some chance a voltage is produced to the frame there is no protection, having it connected inside the box to the ground bar and that is connected to the earth of mains will cause that circuit to trip, thus making it safer.

    Either way you wire is fine, just make sure you have no loops and although unlikely, i would recommend having your frame tied to ground for protection.

    Daniel

  5. #4
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    Apr 2007
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    Victoria
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    Thanks for the info. I'll earth the sheild at the controller end, found an easier way to do it. I'm heading to jaycar to grab some resistors and limit switches now. Will post up some pics of the build in the next day or so.

  6. #5
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    Look forward to seeing your build.

  7. #6
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    Apr 2007
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    Victoria
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    Here are some pics of the machine to date. I cant take the credit for designing and building the frame / gantry as member ttjarret from here did that.
    Cutting area of 875 x 700 x 180mm (xyz). 20mm square linear guide rails. Alluminum extruded frame and 6061 T6 plate for the gantry sides and end plates.

    I have wired the control box and made the DB9 connections. My motor couplings arrived today so will hopefully get the machine running by the weekend. Table top also finished.

    I want to fit limit switches to all axis and use them for homing aswell. Can I just use 3 switches to do this or do I need 6 ? I was hoping to use mach 3 to setup soft limits and use the limit switches as homing switches....?

  8. #7
    Join Date
    May 2003
    Location
    Perth WA
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    Good to see the machine
    Your homing and limit can be the same switch. You can get away with 3 switches if you mount them on the moving element. I find four better as it is difficult in my design to mount them on the gantry sides so I put one each end on the table frame for the X.
    Use quality limit switches if you want accuracy
    One Greg's suggestion I use these and have found them perfect and well priced.
    Cheers,
    Rod

  9. #8
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    Machine and controller look very slick. Keep up the good work.

    Daniel

  10. #9
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    I finished wiring the motors and set the mach3 software up. Spent a couple of hours troubleshooting why I couldnt get my motors to move. I thought I had a straight through parallel cable, turned out to only have 9 wires in it. I will probably have to wait till next week now to run it as the local computer / electronics shops dont sell db25 cables anymore. I could make one but dont feel like soldering the db25's...

  11. #10
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    I bought 2 from Auspcmarket, one is 2m and the other is 5m long. Just in case your still looking. They shipped fairly quick but i'm sure you'll probably find something closer.

    Daniel

  12. #11
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    Quote Originally Posted by HzSandman View Post
    I finished wiring the motors and set the mach3 software up. Spent a couple of hours troubleshooting why I couldnt get my motors to move. I thought I had a straight through parallel cable, turned out to only have 9 wires in it. I will probably have to wait till next week now to run it as the local computer / electronics shops dont sell db25 cables anymore. I could make one but dont feel like soldering the db25's...

    Got a Jaycar near by?

    I know they stock them but they aren't cheap.

    ~$15-20

  13. #12
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    Location
    Victoria
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    Thanks for the heads up, found one at Jaycar today. Can move my motors now Now to figure out how to use this thing....

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