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IndustryArena Forum > CNC Electronics > Servo Motors / Drives > What size are these servos?
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  1. #1
    Join Date
    Sep 2008
    Posts
    100

    What size are these servos?

    Hi,

    I just picked up a couple of dc servo motors, they have the following specs

    Cont. Stall Torque Lb-In (N-m): 40.00 (4.50)
    Cont. Stall Current: 11.2
    Peak Torque Lb-In (N-m): 190 (21.5)
    Peak Current: 46.80
    Torque Constant Lb-In/Amp (N-m/Amp): 3.97 (0.45)
    Voltage Constant v/r/s (V/KRPM): 0.449 (47)
    Resistance: 0.81
    Inductance (mHy): 3.4

    My question is what voltage and max current setting would you suggest running them at and how much power do they develop??

    Other general comments are welcome

    thanks

    Matt

  2. #2
    Join Date
    Dec 2003
    Posts
    24221
    It does not show the max rpm?
    But for a average max for a DC brushed motor, assume 2500rpm, this would require a voltage of 117vdc.
    A linear supply fed from 120vac should provide the required DC.
    The DC supply to the drive should be at least 10% higher than the rated motor voltage.
    30lb-in/amp and cont stall torque of 40lb-in would = 10amps, the cont stall current shows 11amps.
    So if you allow for a drive that will current limit around 11 amps.
    The power rating is a cont torque of 40lb-in.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  3. #3
    Join Date
    Sep 2010
    Posts
    1765
    list mfgr name and part no - lots of us have lots of specific info....... maybe we have data sheets on it.

  4. #4
    Join Date
    Sep 2008
    Posts
    100
    The manufacturer is baldor, the model is sd35-30-a1-a11

    I also have a pair of mk2 gemdrives and the power supply module, i presume thye will be analogue rather than step/dir?

    The max terminal voltage for the motors is listed as 180vdc and the max rpm is 3500, giving a power of 1.5kw??

    Do they sound useful? I bought a pair of ballscrews for my new mill and they came with from an old punch press, do i use them or do i splash out on an ac system from dmm??

    Matt

  5. #5
    Join Date
    Dec 2003
    Posts
    24221
    I couldn't find anything in my data base on those motors? Do they have encoders on them?
    If true servo type they could be very useful at those specs.
    At one time, Baldor made a utility grade DC motor for the Treadmill industry with no encoder fitted.
    Larken drives may drive them if you need step/dir.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  6. #6
    Join Date
    Sep 2008
    Posts
    100
    Thanks for the reply al.

    I found my info here:

    http://www.transaus.com.au/files/TA_Servo_DC_Baldor.pdf

    It lists them as having been replaced by mt4535ctycn

    In what respect do you mean they could be useful with those specs? To me or to sell? I figured i didnt need the power for my axis screws so i might use one as the spindle motor and speed it up 3 to 1 or so??

    They dont have encoders attached, the encoders are connected to the ballscrews.

    Thanks

    Matt

  7. #7
    Join Date
    Dec 2003
    Posts
    24221
    If they are oversized for the machine you have in mind then you could use one as a spindle.
    Generally Baldor have always made good motors.
    For a controller, you could use a construction site 240/120v transformer for power and use a KB or Baldor SCR drive direct off the AC.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

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