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Robot Arm Kit: BYO Servos — Parallax Forums

Robot Arm Kit: BYO Servos

ercoerco Posts: 20,255
edited 2013-08-01 03:48 in Robotics
Thought I found a great deal on a complete 6-axis robot arm kit (bid+ship was ~$84), but most of the Ebay listing is in Chinese. After a bout of BING translation, it appears that the servos are not included. So add six metal gear servos to the total, plus your favorite controller & battery. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=111126127484

Still makes the $99, 5-axis plywood arm kit look good, which includes servos, battery and some kind of controller I never used.
http://www.ebay.com/itm/Robotic-arm-DIY-kit-Lasercut-Plywood-Structure-6servos-AT89S51-MCU-USB-ISP-tool-/330968156179?pt=LH_DefaultDomain_0&hash=item4d0f3d4813

Comments

  • Martin_HMartin_H Posts: 4,051
    edited 2013-07-31 10:49
    I've seen several similar listings for hexapods and quadrupeds. I'm not sure if they're doing that because people prefer it, or people buy in haste and repent in leisure.

    BTW The plywood robot arm we bought was a screaming deal. I figure six servos alone would be worth $70, so we paid $30 for laser cut plywood and hardware. Pololu's laser cutting service would probably charge $20 plus the cost of they plywood, so we essentially got it at cost. I've had a few email exchanges with the guy we bought it from. He's an enthusiast who's watched the forum thread and likes our videos.
  • JLockeJLocke Posts: 354
    edited 2013-07-31 14:05
    I notice that he even has a link to the forum thread in his eBay ad.
  • Martin_HMartin_H Posts: 4,051
    edited 2013-07-31 17:06
    JLocke wrote: »
    I notice that he even has a link to the forum thread in his eBay ad.

    Yes, we're a great ad for his product. When I emailed him he was pleased that we were modifying his basic design. In fact he was extolling the virtues of plywood over aluminum C brackets in this regard. No kidding there are other plywood aficionados out there.
  • ercoerco Posts: 20,255
    edited 2013-07-31 19:22
    Careful, or he'll link to this thread too!
  • ercoerco Posts: 20,255
    edited 2013-07-31 21:20
    Reply from seller in post #1:

    Hello,
    This is no servo, but 119 dollars with 6 servos
    Thank you
    - wester2020

    Still a decent price considering it comes with metal servos and is a full 6 axis arm. The $99 robot is only a 5-axis arm (no wrist rotate), which can be a real limiter. Note that it still uses 6 servos, as two are used on the shoulder lift axis, an excellent feature. IMO the weakest part of the $99 5-axis plywood robot is the shoulder rotate axis, which is just the vertical shaft of the base servo. There is some flex & bounce there. If I understand the translation of the 6-axis arm correctly, the base is acrylic and there is a bearing to steady the shoulder rotate load.
  • Martin_HMartin_H Posts: 4,051
    edited 2013-08-01 03:48
    erco wrote: »
    IMO the weakest part of the $99 5-axis plywood robot is the shoulder rotate axis, which is just the vertical shaft of the base servo. There is some flex & bounce there. If I understand the translation of the 6-axis arm correctly, the base is acrylic and there is a bearing to steady the shoulder rotate load.

    I agree and I added some Teflon furniture glides to that axis which eliminated most of the bounce.
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