I need advice about stepper motors

Discussion in 'The Projects Forum' started by circuit4, Mar 21, 2011.

  1. circuit4

    Thread Starter New Member

    Mar 21, 2011
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    Hello,
    I need to find a replacement for an old stepper motor. I do not much about the stepper motors and electronics overall, but any help is appreciated. I look for a new stepper that can be operated with a computer (preferably w/ a USB driver or GPIB). I copy the machines specs below, do you have any suggestions for me? (The machine is too told that I couldn't single information about it online).

    Airpax
    B82408

    5V 3.5W ROT REV
    RPM 0-16.8
    PPS 0-280
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Are you looking for a functional replacement to go in the place of the old Airpax, or are you simply looking to run a stepper from a computer?

    That number does not turn up anything. Airpax makes a zillion different steppers. It may be that yours was made under contract and has no commercial equivalent.

    The link has a lot of information about steppers, which may let you figure a possible replacement - http://www.cs.uiowa.edu/~jones/step/
     
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  3. circuit4

    Thread Starter New Member

    Mar 21, 2011
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    Thanks for the reply,

    I am looking for a replacement, because this airpax is too old fashioned that we cannot connect it to the computer. So basically I look for a replacement that has similar features and I can control with a computer. Actually this stepper motor is integrated to a monochromator. We want to replace the motor so we can operate the monochromator manually (Like most devices in the lab can be controlled by some software, such as Labview).

    Would you suggest any particular company or model?
     
  4. GetDeviceInfo

    Senior Member

    Jun 7, 2009
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    because Labview gives you access to most of your computer's hardware ports, I'd suggest googling for stepper motor serial port or parallel port. You should find plenty of hobby and commercial offerings.
     
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  5. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    It sounds to me that the difficulty is not the stepper motor itself; it is the lack of an interface between the stepper motor and the computer - whether serial (USB or RS-232), parallel (LPTx: ), GPIB, etc.

    From the notes you wrote down, it appears that the windings are specified for 5v operation @ 3.5W, or 0.7 Amperes.
    You did not mention how many wires the motor has.
    4 wires = Bipolar stepper or possibly a BLDC (3-phase) with 1 common.
    5 wires = Unipolar stepper with 1 common (center tap).
    6 wires = Unipolar stepper with 2 commons, can be run as bipolar with 10v leaving commons unused.
    8 wires = universal type; can be operated as bipolar or unipolar.

    You will need a multimeter to start sorting out the wires, measuring Ohms from each wire to all other wires. Start by labeling the wires with pieces of tape and a marker, "A", "B", etc. and writing down the resistance measured between each pair of wires.
     
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  6. circuit4

    Thread Starter New Member

    Mar 21, 2011
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    @GetDeviceInfo,
    Would you suggest company?

    @SgtWookie,
    I will try to do that when I have access to the motor.

    Right now I'd really appreciate some company suggestions.
     
    Last edited: Mar 30, 2011
  7. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    I can't give recommendations on stepper motor drivers that interface to a computer.

    However, you might check over here: http://cnczone.com/
    There are lots of people on those forums who are CNC hobbyists, who have interfaced multiple stepper motors to computers.

    Since you only need one stepper-to-computer interface, it should be somewhat easy.
    Since your control requirements are different (computer software interface), that may be a significant hurdle to overcome.

    But first, you need to find out more about your motor. I get nothing but dead ends trying Google searches.
     
  8. Rbeckett

    Member

    Sep 3, 2010
    205
    32
    There is a document called "Jones on Stepper motors" that is a gold mine of info. It will answer most if not all of your questions or direct you to more advanced reading if you need it. The doc is rather old, but still very valid. I think the doc is at the University of Iowa or some other school close by. If you cannot find it I will look into my files and see if I have a copy and email it to you. Good luck!!!
    Bob
     
  9. circuit4

    Thread Starter New Member

    Mar 21, 2011
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    Thanks for the links Rbeckeett.

    I am attaching some pictures of the device. It turns we don't know if the motor is working or not, we have used it only manually so far. So if you have any idea about it, let me know.

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
     
  10. circuit4

    Thread Starter New Member

    Mar 21, 2011
    5
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  11. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    That is not just a "stepper motor". It has a gear box on it. It may even be a BLDC motor(Brush Less DC). How many wires are actually coming out of the main motor casing? Its hard to see in the photo. They normally don't use a stepper motor and a gear box together, that, low RPM, is one of the reasons for using a stepper motor.
     
  12. shortbus

    AAC Fanatic!

    Sep 30, 2009
    4,004
    1,523
    @ Circuit4 - In your first post you listed the motor specs. as the following -

    5V 3.5W Rot Rev

    RPM 0 - 16.8

    PPS 0 -280

    Think you'll find this to mean -

    5V 3.5W ROTation REVersible

    RPM 16.8

    Pulse Per Second

    These are not normal specifications for a stepper motor. They are usually some thing like - 5V 3.5W 1.8 degrees / 200 steps per rotation.

    To figure out the motor you need, your going to have to do some investigating. You'll have to remove the motor from the gearbox to figure out if it is a reducing or multiplying gearbox. Then from there you can figure out if you actually have a stepper motor or some other type of motor.

    The only way from the specification printed on the motor that it could/would be a stepper motor is if the gearbox is a 5:1 reduction ratio gearbox. A stepper motor running at 280 PPS would give 16.8 RPM at that rating. The math follows;

    280 PPS x 60 seconds in minute = 168000 steps per minute

    168000 steps/min divided by 200 steps/revolution = 84 RPM

    84 RPM divided by 5 = 16.8 rpm out put of gearbox
     
  13. stillLost

    New Member

    Feb 3, 2012
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    @circuit4

    Did you ever get your monochromator working? I have the same model and what appears to be the same motor, but with a 9-pin D interface. I would love to know how you got it connected to a computer

    Thanks!
     
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