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Servo Motors

ArchiverArchiver Posts: 46,084
edited 2000-10-07 20:48 in General Discussion
I need to pull a metal pin that is about .500" (1.27cm) in diameter out of a
mating receptacle. The amount of force required for the pull is about 6
linear pounds (2.7 kg).

The issues are the cost and size of the standard servos.

Does anyone have any ideas of what to use that will fit into an
approximately 1.5" ( 3.8 cm) diameter tube?
The required travel distance is about .250" (6.3mm).

Comments on this one Ronald Doctors?

Thanks.

David

Comments

  • ArchiverArchiver Posts: 46,084
    edited 2000-03-16 17:25
    David,

    There's a standard type of linear actuator that uses a stepper motor with a
    threaded shaft through the center... And you could do something similar by
    using a conventional motor to turn a nut that draws a threaded shaft
    through the required stroke. Industrial equipment vendors sell complete
    assemblies for jobs like this.

    >I need to pull a metal pin that is about .500" (1.27cm) in diameter out of a
    >mating receptacle. The amount of force required for the pull is about 6
    >linear pounds (2.7 kg).

    Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
    Manufacturer of the famous BOB-II Serial Video Text Display Module!
  • ArchiverArchiver Posts: 46,084
    edited 2000-03-16 18:32
    Mike:

    Is there any reason for precision positioning? Or are you just wanting to
    pull the pin out of a detent or locking hole and then have the ability to
    re-insert it? If all you are doing is moving the pin in and out there are
    tons of linear actuators out there that should be able to do the job with
    simply and on and off command. If you have compressed air available a simple
    double action air cylinder and inexpensive electric solenoid air valve would
    solve the problem

    Hope this helps
    Randy A.
  • ArchiverArchiver Posts: 46,084
    edited 2000-03-16 20:23
    How fast do you need to do this. Withe correct gearing a tiny motor can move a
    mountain!

    From: "David Covick" <dac@w...>
    To: "PIC STAMP LIST" <basicstamps@egroups.com>
    Date sent: Wed, 15 Mar 2000 21:24:48 -0800
    Send reply to: basicstamps@egroups.com
    Subject: [noparse][[/noparse]basicstamps] Servo Motors

    > I need to pull a metal pin that is about .500" (1.27cm) in diameter out of a
    > mating receptacle. The amount of force required for the pull is about 6
    > linear pounds (2.7 kg).
    >
    > The issues are the cost and size of the standard servos.
    >
    > Does anyone have any ideas of what to use that will fit into an
    > approximately 1.5" ( 3.8 cm) diameter tube?
    > The required travel distance is about .250" (6.3mm).
    >
    > Comments on this one Ronald Doctors?
    >
    > Thanks.
    >
    > David
    >
    >
    >
    >
    >
    >
    >
    >
    > eGroups.com home: http://www.egroups.com/group/basicstamps
    > http://www.egroups.com - Simplifying group communications
    >
    >
    >
    >


    ron... the motor man...
    Ronald Doctors
    http://www.members.home.net/rdoctors
  • ArchiverArchiver Posts: 46,084
    edited 2000-03-17 01:46
    Mike, Randy, Ronald,

    Thanks all for the response.
    The linear actuator that uses a stepper motor sounds like a plan but may be
    to costly for my little project. I will certainly look into this though!
    Yes, the pin will be "re-inserted" by the actuator. This a battery powered
    device....low power is the key.

    Ronald, Your idea of a motor and gears is interesting too. I worked with
    some tiny maxon? motors about 10 years ago. Very powerful. In fact, I used
    it in a microwave oven turntable. I captured the microwave energy from
    inside the oven using a "rectenna" rectifying it before the motor. Very
    slow speed and powerful for the turntable, but the
    motor was turning fast.

    You've all given me some clues. Thanks!!

    David

    Original Message
    From: Mike Hardwick <decade@w...>
    To: <basicstamps@egroups.com>
    Sent: Thursday, March 16, 2000 9:25 AM
    Subject: [noparse][[/noparse]basicstamps] Re: Servo Motors


    > David,
    >
    > There's a standard type of linear actuator that uses a stepper motor with
    a
    > threaded shaft through the center... And you could do something similar by
    > using a conventional motor to turn a nut that draws a threaded shaft
    > through the required stroke. Industrial equipment vendors sell complete
    > assemblies for jobs like this.
    >
    > >I need to pull a metal pin that is about .500" (1.27cm) in diameter out
    of a
    > >mating receptacle. The amount of force required for the pull is about 6
    > >linear pounds (2.7 kg).
    >
    > Mike Hardwick, for Decade Engineering -- <http://www.decadenet.com>
    > Manufacturer of the famous BOB-II Serial Video Text Display Module!
    >
    >
    > eGroups.com Home: http://www.egroups.com/group/basicstamps/
    > http://www.egroups.com - Simplifying group communications
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-07 14:08
    I want something as precise as a servo but that can make a full 360
    degree turn. help
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-07 14:38
    Buy a servo- modify it for full rotation. The mod is well documented in the
    BOE-bot manual (available for down load from the Parallax website. I have
    done it with very little difficulty; if I can do it, <<anyone>> can [noparse];)[/noparse]

    Good luck.

    peter

    Peter C. Charles, Ph.D.
    Research Assistant Professor
    Department of Microbiology and Immunology
    Rm. 730 Mary Ellen Jones Building, CB# 7290
    UNC
    Chapel Hill, NC 27599-7290

    "He that but looketh on a plate of ham and eggs to lust after it, hath
    already committed breakfast with it in his heart."

    --C.S. Lewis


    Original Message
    From: gmonrose@j... [noparse]/noparse]mailto:[url=http://forums.parallaxinc.com/group/basicstamps/post?postID=4rRyBzahoOFtWxr-In79xVPWyflfWUyQ3DE6IOuhbMEvTtQSzDFFLjrRNPD4X4eaHyF5W3HNRrW7qy_E]gmonrose@j...[/url
    Sent: Saturday, October 07, 2000 9:08 AM
    To: basicstamps@egroups.com
    Subject: [noparse][[/noparse]basicstamps] Servo motors


    I want something as precise as a servo but that can make a full 360
    degree turn. help
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-07 14:41
    I found some good servos and motor here

    http://www.technologyindex.com/

    Original Message
    From: <gmonrose@j...>
    To: <basicstamps@egroups.com>
    Sent: Saturday, October 07, 2000 2:08 PM
    Subject: [noparse][[/noparse]basicstamps] Servo motors


    > I want something as precise as a servo but that can make a full 360
    > degree turn. help
    >
    >
    >
    >
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-07 17:29
    > I want something as precise as a servo but that can make a full 360
    > degree turn. help

    Servos can be modified for continuous rotation quite easily. Follow
    the link on:

    http://www.hvwtech.com/servos.htm

    to a photo tutorial on how it's done.


    Mark Hillier, VE6HVW
    President, HVW Technologies Inc.
    Canadian Distributors of Parallax Products and other Neat Stuff
    Tel: +403-730-8603 Fax: +403-730-8903
    http://www.hvwtech.com
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-07 17:41
    True, but keep in mind that you will lose positional control of
    the servo, unless you add some sort of an external feedback.

    I've found that you can squeeze close to 180 degrees of rotation
    out of a standard hobby servo, without any modification. If this
    pan/tilt setup will be mounted against a wall or in a corner, I would
    think that you'd do fine with unmodified servos. As always, YMMV.

    Cheers,

    Steve


    << > I want something as precise as a servo but that can make a full 360
    > degree turn. help

    Servos can be modified for continuous rotation quite easily. Follow
    the link on: >>
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-07 18:53
    Oooops, I didn't catch the original posting mentioning that this
    will be ceiling mounted (in the center of the room?). How about
    a standard servo for the tilt mechanism, and a cheap stepper
    motor for the pan mechanism?

    Cheers,

    Steve

    << If this pan/tilt setup will be mounted against a wall or in a
    corner, I would think that you'd do fine with unmodified servos. >>
  • ArchiverArchiver Posts: 46,084
    edited 2000-10-07 20:48
    >I want something as precise as a servo but that can make a full 360
    >degree turn. help
    >

    Assuming that you are not looking for rotation, (as the other posts are),
    and are looking rather for precise posisioning within 360 degrees, you
    can use a servo with a 4/3 gear ratio to your controlled device or a stepper
    motor with some kind of position feedback.
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