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Nice Cheap Servo for Continuous Rotation Modification — Parallax Forums

Nice Cheap Servo for Continuous Rotation Modification

ercoerco Posts: 20,255
edited 2015-03-19 19:20 in Robotics
I'm building one or two small mobile robots each week now (oh, how I love my new job!) and I've been modifying several different cheap standard-size servos for continuous rotation. Some are easier to mod than others, some have better fine motor control. This week's favorite is Hobby King's Turnigy TGY-S4505B .

1) It's cheap, $5.10-$5.65 depending on Int'l vs US warehouse and if you wait a while to order (discount offered)
2) Dual ball bearings for long life
3) Doesn't need the internal pot for support. Just snip off the plastic pot shaft and it's mechanically disconnected.
4) Snip a single post off the output gear for 360 degree rotation
5) Unsolder 3 pot wires (note color, they vary) and route thru a small hole in the case to an external 5-10K trimpot.
6) Excellent center stop stability
7) Excellent fine motor speed control
8) 1.75" diameter circular servo horn included makes a fine free instant wheel, just cut a rubber band "tire" out of an old road bike innertube.

It uses nylon gears, so don't overload it, but I was pleasantly surprised how well this one works. I hate re-nulling drifty CR servos every other day, and so far I haven't had to with these. A five-star thumbs-up from erco, I'm ordering more.

Edit: Servos driving 1.75" servo horn "wheels" at 6V (4xAA) gives maximum forward speed of ~7"/sec.

Comments

  • NWCCTVNWCCTV Posts: 3,629
    edited 2014-11-10 18:02
    Are you working from home now?
  • ercoerco Posts: 20,255
    edited 2014-11-10 18:37
    Yes, consulting and inventing. Best of both worlds!
  • GordonMcCombGordonMcComb Posts: 3,366
    edited 2014-11-11 08:51
    erco wrote: »
    Yes, consulting and inventing. Best of both worlds!

    So what would they call this combination of consulting and inventing? How about ConVenting? Or there's always InSulting!

    Welcome to the world of work-at-home, pal! Just remember to change out of your jammies if you make a quick trip for hardware at the Home Depot.
  • WhitWhit Posts: 4,191
    edited 2014-11-11 19:51
    Just remember to change out of your jammies if you make a quick trip for hardware at the Home Depot.

    Or send a tele-presence robot out on the chores and stay in your jammies!
  • WhitWhit Posts: 4,191
    edited 2014-11-11 19:57
    erco wrote: »
    I'm ordering more.

    And selling more... You sir, are a menace!
  • ercoerco Posts: 20,255
    edited 2014-11-11 20:42
    Whit wrote: »
    And selling more... You sir, are a menace!

    At least I've learned to order all I want before posting. I've previously had some good parts bought right out from under me when I shared before ordering. Only after I hoard do I turn you vultures loose to feast on the leftovers. :)

    I still gotta figure a way to get my 5%.
  • ercoerco Posts: 20,255
    edited 2014-11-13 09:38
    Or there's always InSulting!

    I missed that initially. Very well crafted, good sir! I am indeed a paid professional InSultor.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-11-13 10:17
    Just remember to change out of your jammies if you make a quick trip for hardware at the Home Depot.

    This is the main reason I buy my hardware online.

    And they're not jammies; they're work clothes!
  • ercoerco Posts: 20,255
    edited 2014-11-14 14:14
    Duane Degn wrote: »
    This is the main reason I buy my hardware online.

    Online? Impossible for most plumbing repair jobs from my experience. It's maddening staring at the wall of various fittings at Home Depot, trying to get all the parts, valves and NPT, street elbow parts to fit together for any particular application. Click & order will never replace brick & mortar (thank goodness) for most one-time jobs IMO.

    And no, I've never had any complaints about my PJs! I keep my drop seat firmly buttoned for the most part.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2014-11-14 20:42
    they're work clothes!
    Boxers or Briefs?
  • ercoerco Posts: 20,255
    edited 2014-11-14 21:37
    NWCCTV wrote: »
    Boxers or Briefs?

    "Depends", said the old fellow.
  • ercoerco Posts: 20,255
    edited 2015-03-19 15:09
    Here are some nice ones already set up for continuous rotation, no modification required. Also comes with a 1.75" servo horn wheel. BIN two for $16, or you can win them in auction for ~$6 occasionally. I bought two and was impressed, they have nice slow speed control and when I hooked these cheap Ebay servos up to my cheap Ebay servo tester, they were PERFECTLY calibrated to stop in the center position. A very good sign!

    Spring RC SM-S4303R

    http://www.ebay.com/itm/231493244643
  • Martin_HMartin_H Posts: 4,051
    edited 2015-03-19 18:46
    I have a pair of Spring RC servos and like them. They're geared down a bit, so the have 71 oz/inch of torque which I combined with higher traction wheels to give my Boe-bot some authority when it moves.

    My previous favorites were GWS CR servos that tolerated 7.2 volts. But these are a bit better.
  • ercoerco Posts: 20,255
    edited 2015-03-19 19:20
    Martin_H wrote: »
    But these are a bit better.

    High praise indeed from Martin, the Master of Mechanical Mayhem! Happy to hear you concur.
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