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Source for quality, high torque, low rpm (4-6rpm) 12V motors (with wheels too)? — Parallax Forums

Source for quality, high torque, low rpm (4-6rpm) 12V motors (with wheels too)?

vanmunchvanmunch Posts: 568
edited 2012-04-20 16:12 in General Discussion
Hey Everyone,
I’ve been building a new wheeled robot and I need help finding a good place to buy quality, high torque, low rpm 12V motors. Ideally, I would like to be able to buy wheels from the same place but that’s not a deal breaker.

I’ve been using Parallax’s wheel kit:
http://www.parallax.com/Store/Accessories/MotorServos/tabid/163/CategoryID/57/List/0/SortField/0/Level/a/ProductID/507/Default.aspx
but their rpm is too high and their torque is too low.

The robot I’m building will weight ~150-200lbs, but only needs to travel at 5-10 ft per minute or ~4-6rpm with 6” tires.
I’d like to stick with 12 volts because I’m using HB-25 motor controllers:
http://www.parallax.com/Store/Accessories/MotorServos/tabid/163/CategoryID/57/List/0/SortField/0/Level/a/ProductID/64/Default.aspx

Please let me know if you have any ideas or if you think that it can’t be done with 12V. I’d rather find out now that I’m crazy than buy some and learn the expensive way! :)
Thanks!
Dave

Comments

  • Beau SchwabeBeau Schwabe Posts: 6,568
    edited 2012-04-07 15:32
    vanmunch,

    I've used cordless screw drivers before to drive lawnmower wheels... And I've run them at 12V but not for very long :-) ... They should be ok at 6V which is the minimum motor supply voltage for the HB25.

    Note: You might need to disable the locking mechanism of the cordless screw driver... I haven't done this in awhile, but it's as trivial as removing a single pin.

    Alternatively you can look into windshield wiper motors... essentially that's all the motor mechanism is in the Motor Mount and Wheel Kit
  • al1970al1970 Posts: 64
    edited 2012-04-07 22:29
    Hi:

    If you don't mind blowing $50 on an idea. I don't know if you can put a wheel on it but I have used electric winch before on an arm.. The kind you use for a truck that can be picked up at Walmart for about $50. They work on 12 volts and are strong and slow. It is very easy to make it go CW and CCW by bypassing a relay and a gear stopper. I have used it to lift 100 lb. bags and the bags stay even when the power is off. I don't think you will find anything that gear down and cheap.

    Al


    vanmunch wrote: »
    Hey Everyone,
    I’ve been building a new wheeled robot and I need help finding a good place to buy quality, high torque, low rpm 12V motors. Ideally, I would like to be able to buy wheels from the same place but that’s not a deal breaker.

    I’ve been using Parallax’s wheel kit:
    http://www.parallax.com/Store/Accessories/MotorServos/tabid/163/CategoryID/57/List/0/SortField/0/Level/a/ProductID/507/Default.aspx
    but their rpm is too high and their torque is too low.

    The robot I’m building will weight ~150-200lbs, but only needs to travel at 5-10 ft per minute or ~4-6rpm with 6” tires.
    I’d like to stick with 12 volts because I’m using HB-25 motor controllers:
    http://www.parallax.com/Store/Accessories/MotorServos/tabid/163/CategoryID/57/List/0/SortField/0/Level/a/ProductID/64/Default.aspx

    Please let me know if you have any ideas or if you think that it can’t be done with 12V. I’d rather find out now that I’m crazy than buy some and learn the expensive way! :)
    Thanks!
    Dave
  • vanmunchvanmunch Posts: 568
    edited 2012-04-08 19:05
    Hi Guys,
    Thanks for the good advice and ideas. I’ve been looking some more at used power chairs and comparing them what it would take to find wheels, wheel mounts, ect. for a custom 12v system and not too surprising… it’s a lot cheaper to just buy a used power chair and use a Sabertooth 2X60 motor controller. I’ll let you know how the project goes, it should be done by mid June.
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2012-04-08 19:15
    Keep an eye on your local Craigslist ads. You can sometimes score a great deal on one that isn't working well because of old batteries. If the peak loads end up exceeding the Sabertooth controller you may also want to look into the larger OSMC controllers. I have those on a couple large robots and they work well.

    Robert
  • T ChapT Chap Posts: 4,223
    edited 2012-04-08 19:49
    Allelectronics.com. I was in LA for many years, they have a variety of scooter motors, windshield wiper motors etc. The windshield wiper motors are slow with a lot of torque, it would not be hard to add wheels.
  • vanmunchvanmunch Posts: 568
    edited 2012-04-09 08:29
    Robert, T Chap,

    Thanks for the advice! I'll check them out. :)
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-04-09 10:18
    Power chair motors are the best for this type of weight, but of course they are the most expensive of the bunch. You used to be able to find them for $50-75, then the combat robot folks discovered them and the going rate is more like $250. Each.

    Motors for automotive applications are good sources of cheap and high torque, but do keep in mind the motors are intended for intermittant duty only. This is especially true of starter motors.

    When you work with this much torque it's often a good idea to use a more "giving" power transmission between the motor and wheel. You can achieve just that with a nice V-belt arrangement, AND enjoy more torque and lower speed. Put a small pulley on the motor, and place a larger pulley on the inside of the wheel. (Obviously the pulley needs to be a smaller diameter than the wheel!)

    You then only need to put the wheels on bearing shafts, which is cheaper than augmenting the output shaft of the motor in order to accommodate the weight. I would surmise you could keep the Parallax motor and wheel kit, and just devise (say) a 10:1 V-pulley system. Not counting frictional losses, you get 10X the torque (and /10 the speed). You can try keeping the 6" wheels that come with the kit, or go with some beefier pneumatic wheels from Harbor Freight.

    -- Gordon
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-04-09 10:41
    Beau Schwabe (Parallax) wrote: »
    Alternatively you can look into windshield wiper motors... essentially that's all the motor mechanism is in the Motor Mount and Wheel Kit

    Beau,

    I'm guessing you meant power window motors? I don't think the windshield wiper motors are as strong. Plus with windshield wiper motors, the robot would just go forwad and then back not making much progress. :smile: (Yes, I know they could be modified to just move forward (I was being funny (I often have to point this out when I make a joke)).)

    Edit: I see T_Chap also referred to windshield wiper motors. Are they really windshield wiper motors or power window motors?
  • T ChapT Chap Posts: 4,223
    edited 2012-04-09 11:22
    I mentioned windshield wiper motors, however, All has a lot of different motors, some with gears which are slow running and high torque. Search their site for "motor" and see a lot more. Some of these gear motors are really high torque.

    http://www.allelectronics.com/make-a-store/item/DCM-697/12VDC-RIGHT-ANGLE-GEARHEAD-MOTOR-WITH-WORM-DRIVE/1.html
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-04-09 11:38
    T Chap wrote: »
    I mentioned windshield wiper motors, however, All has a lot of different motors, some with gears which are slow running and high torque. Search their site for "motor" and see a lot more. Some of these gear motors are really high torque.

    http://www.allelectronics.com/make-a-store/item/DCM-697/12VDC-RIGHT-ANGLE-GEARHEAD-MOTOR-WITH-WORM-DRIVE/1.html

    Thanks for the reply T_Chap. I don't think I have heard of windshield wiper motors being used in robotics before. I guess they do need a lot of torque to move snow and slush at the end of such a long arm.

    I had thought the Parallax motor set, Beau linked to, used power window motors, not windshield wiper motors. This made me wonder if you had just referred to windshield wiper motors since Beau had.

    Now I see windshield wiper motors are also a good choice for robot motors.

    I'm still unclear about the Parallax motors. Are they windshield wiper motors or power window motors?
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2012-04-09 11:48
    Duane Degn wrote: »
    I'm still unclear about the Parallax motors. Are they windshield wiper motors or power window motors?

    I am sure they are power window motors. I've never seen wiper motors come in Left and Right hand versions (although someone probably makes them for some odd import).

    I wouldn't recommend using starter motors for a robot drive. Those can gobble up a ton of power and would drain your batteries before you know it.
  • TtailspinTtailspin Posts: 1,326
    edited 2012-04-10 07:07
    They are Windshield wiper motors. :smile:



    -Tommy
  • localrogerlocalroger Posts: 3,452
    edited 2012-04-10 07:59
    A few years ago I built a trike bot with two windshield wiper motors that American Science & Surplus was selling at the time. They were very powerful, and that bot had no trouble rolling through grass twice as tall as it was.
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2012-04-10 11:34
    Automotive motors in order of preference:

    Windshield wiper (they're made for continuous duty, but as noted, not all are capable of reversing -- check first!)
    Power window
    Power seat
    ... way down the list...
    Starter (not all can be reversed; consumes lots of current; definitely not for anything but short duty)

    A couple of other options popular in surplus:
    DC winch (for cars, runs at 12V)
    Golf cart motors (most are for 24-36V, but can run okay at 12V at lower torque)
    Old-school satellite dish positioners

    This motor seems a good candidate. Have no idea what its duty is, and the "inch-pounds" spec looks a bit suspicious. Cheap enough to try, and AmSci does allow returns (AFAIK).

    http://www.sciplus.com/recommend.cfm/recommendid/15332

    -- Gordon
  • idbruceidbruce Posts: 6,197
    edited 2012-04-10 11:49
    vanmunch

    Take a look at these robot kits. You might get some ideas on gearing up or gearing down motors to meet your requirements. Bruce
  • vanmunchvanmunch Posts: 568
    edited 2012-04-20 13:01
    Hey everyone,

    Thanks for the great info and advice! I'm still trying to get caught up from traveling to the UPEW.

    I've managed to buy a decent power chair and the Sabertooth 2X60 is handling it just fine. I just have to be a bit careful now... there's enough torque to take my hand off...


    The project should (fingures cross) be done in ~2-3 months and then I'll post some more info. :)
  • W9GFOW9GFO Posts: 4,010
    edited 2012-04-20 16:12
    Electric wheelchair motors would be my first choice but there are also the $25 CIM motors which are used on the 140lb FRC robots.

    http://www.andymark.com/product-p/am-0255.htm
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