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Dollar Servos — Parallax Forums

Dollar Servos

ercoerco Posts: 20,256
edited 2010-10-27 14:33 in Robotics
A while ago, I was amazed to find small 9g servos for ~$2.40 each in batches of 12. I ordered a bunch from HK, and they work fine. Not super-high quality, and they cannot be made into continuous servos since they only have an output gear sector (half a gear). But to play around with and think about making a gazillion-servo walker or such, they are well worth it.

Well, I just found two servos for $2.33 (free shipping from HK) at http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=110579827241 and ordered 8 more. Let's see, a cheeseburger, or a servo? I have to wonder if they can ever be cheaper than this, or will this seller come to his senses and raise his price?

Similar servos can be bought in the US from http://www.hobbypartz.com/topromisesg9.html for $2.77.
!Bz4sPKgB2k~$(KGrHqUOKj0E)OikY4ZQBM(9uOuiB!~~_12.JPG
400 x 400 - 58K

Comments

  • RavenkallenRavenkallen Posts: 1,057
    edited 2010-08-30 19:24
    Yeah, hobbypartz is where i buy my servos from. They actually have really good prices compared to others. For continuous rotation, i just hack it apart. First, i tear out the drive electronics entirely. Then i solder some wires directly to the motor. The last step is to saw the notch off so that it will rotate 360 degrees... It is like having a regular DC motor, only it is more powerful and has better connectors....i actually have those EXACT servos.
  • P!-RoP!-Ro Posts: 1,189
    edited 2010-08-30 19:40
    Hobbyking has one for $1.99. http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=9549
  • Paul K.Paul K. Posts: 150
    edited 2010-08-31 00:45
    Heres a little pic of a project I've been working on. It uses the hextronik 9G servos from Hobbyking. There beefier than the Hitec 55's and cost a fraction of their price.

    The left is the final prototype(hextronik servos) and the right is the orginal(hitec HS-55's). It runs on a Prop and it has an IK engine as well as several different walking gaits. I plan to start my own thread(finishing up some videos) but just saw this and thought I'd show what I used these cheap servos.
    IMG_1717.jpg
    800 x 600 - 87K
  • ercoerco Posts: 20,256
    edited 2010-08-31 09:27
    Beautiful! I figured someone would beat me to it! That's just the servo-intensive kinda walker I was imagining. Please do follow up with videos!
  • ercoerco Posts: 20,256
    edited 2010-08-31 23:33
    Perhaps it WAS too good to be true. I just got an email that my Paypal payment was refunded, but no explanation was made. The item is no longer offered at that price by the seller. I emailed the seller, no reply yet.

    Per my original post, "will this seller come to his senses and raise his price"?

    Apparently so.
  • HumanoidoHumanoido Posts: 5,770
    edited 2010-09-01 04:21
    You find these kinds of deals all over China. But let the buyer beware. A lot of these are reject standards that didn't meet the specs for one reason or another. If you're lucky, its just stuff from a company that went out of business and the product is working. For hobby apps, you could always buy 20 and repair some using parts from others.

    Humanoido
  • lardomlardom Posts: 1,659
    edited 2010-09-01 06:28
    Just yesterday I paid $12.99 apiece for two servos at a local hobby shop. I want to start experimenting with multiple motors. You learn as you go along.
  • vanmunchvanmunch Posts: 568
    edited 2010-09-03 16:15
    @Paul K

    Looks great, what did you use to machine your parts? I look forward to seeing your videos!
  • Paul K.Paul K. Posts: 150
    edited 2010-09-04 20:26
    I converted a grizzly mill over to cnc. Its beefier than a sherline, it can take bigger cuts and is faster.

    Videos will be up tommorrow.

    I saw the video of your hex with the prop. Nice work. You posted a comment on my youtube account as well. (QuantumRoboticsInc's channel)

    The little blue hex was the first proto type. Since then I went from foward kinematics to inverse kinematics.

    Your board looks like my first prototype and should run the code no problem. I will make the code public to as it uses objects posted here.
  • Paul K.Paul K. Posts: 150
    edited 2010-10-26 22:25
    Here's a small follow up. I dont want to drift from the topic of this thread but a follow up was requested.

    Here are those little servos at work. For the money they are tough little guys.

    http://www.youtube.com/watch?v=eddcCu5X9iM&feature=player_embedded

    Older vid using Foward Kinematics. 1st prototype.

    http://www.youtube.com/watch?v=wK5A97Wyqtc&feature=fvwk

    I will be making a dedicated thread on my large hex and will go into details and post code. I finally got the code cleaned up.

    You can take a look at the most recent video as well its under my profile on youtube.
  • ercoerco Posts: 20,256
    edited 2010-10-27 09:27
    Paul: Beautiful work, both mechanically and coding! Well done.

    Nice to hear a glowing review and recommendation for $3 servos. Do you have a link to your Hextronic servo source?
  • Paul K.Paul K. Posts: 150
    edited 2010-10-27 14:33
    Thanks

    http://hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=662 is the link. I usually stock up on things when I place an order so the shipping charge dosent sting that much.
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