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  • surplus motors

    I posted earlier about the usefullness of sewing machine (home, not industrial) motors. Lot of posts here about treadmill, winshield wiper and power seat motors and their adaptability to most anything.

    Offered an automobile starter motor (Chrysler, about 5 inches long by 3 or so in diameter - for sure, not to start a 440 hemi).

    While dc they sure spin at high revs. Wondering if these are useful for machining endeavors? Evidently need some slowing down - gears or pulleys.

    Can they be adapted to use the electronic controllers?

    Interested in any experiences by forum members.

  • #2
    Might make an intresting low voltage servo if you PWM limited the current down enough.
    they definately are not designed for 12v operation for any length of time. Still, add in a worm gear+a thermal cutout fuse and they would make for some nice fast position adjusters of something. (winchs, linear worm gear setups, etc)
    Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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    • #3
      Starter motors are designed to spin one with with much torque. It might be good for something like an industrial 12V die grinder.

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      • #4
        Originally posted by Black_Moons
        Might make an intresting low voltage servo if you PWM limited the current down enough.
        they definately are not designed for 12v operation for any length of time. Still, add in a worm gear+a thermal cutout fuse and they would make for some nice fast position adjusters of something. (winchs, linear worm gear setups, etc)

        Does anyone (yourself perhaps) have a nice schematic for a PWM device that could harness a car starter motor for low speed drive service. I built a reverse drive unit for my Harley sidecar. It drove a roller on the sidecar wheel that was pulled into place.

        It worked very well but the only problem was that I was using a 12 VDC Winch. It had lots of power but it's way too slow. I thought of a starter motor but ran into my lack of knowledge of PWM's. It's sitting in a box awaiting a different motor.

        As you know, starter motors have almost no resistance. Typically they can pull over 100 amps on 13 VDC from a car with no current device in place. I need to limit the current a great deal.

        Any suggestions would be appreciated.
        Last edited by gnm109; 11-20-2009, 11:56 AM.

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        • #5
          Can't say that I do.. it requires some basic analog knowage, but generaly what you'll end up with is some kinda osillator, idealy with current feedback to automaticly adjust current as the motor is loaded down, controling a really big mosfet to switch on and off at 10khz+, varying the duty cycle to maintain the same current
          Play Brutal Nature, Black Moons free to play highly realistic voxel sandbox game.

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          • #6
            Run time will be your biggest issue. A starter motor is generally not rated for continuous duty.

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            • #7
              Only good in the right application...

              A starter motor is designed for High Current-High Torque. Is is great for short run times (like starting a car). If you need High Torque you will also need BIG (VERY BIG) power supplies and if you can afford big power supplies you can probably afford a better motor/supply combuination that will work much better.

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              • #8
                The answer is no. A starter motor is series wound and its speed is only limited by the load or when it flies apart. In short it is either running away or bogging down. It will only survive under heavy loads and very short runs.

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                • #9
                  Yeah, I'll keep looking for another type of motor.

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                  • #10
                    Originally posted by Dunc
                    Offered an automobile starter motor (Chrysler, about 5 inches long by 3 or so in diameter - for sure, not to start a 440 hemi).
                    That size is likely a PMGR and yes it will crank a 11:1 440 Hemi. All the race cars here use small PMGR starters, very reliable. The old big round kind are junk on a race car, excellent source of trouble.

                    But to the OP - not really for continuous duty.
                    Chris
                    Merkel, Tx
                    http://raceabilene.com/kelly/hotrod

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                    • #11
                      Most starter motors run in plain oilite bushings, not very durable for continious duty. And most are shunt wound and not intended to run for more than a few seconds, they also have the disadvantage of field and armature windings designed for high current loads. There are permanent magnet field starter motors available but with bushing bearings, they're still pretty expensive. A good ball bearing, permanent magnet DC motor would be very expensive from automotive sources.

                      Were I to need a high torque DC motor, to power a machine, I would probably be looking in the newspaper ads for a treadmill or other exercise machine. With their own motor control and good torque, they're actually a bargain, as long as nobody makes you use it for what it was designed for.
                      No good deed goes unpunished.

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