Need a $13 Robot Arm?

Flash sale, whatever that means. Never again? EVER? https://www.gearbest.com/novelty-toys/pp_009244385861.html Looks like a uArm style arm.

Pretty sure the four 9G servos are not included, but the hardware (screws & such) is. BYO controller.

I still like Hobby King's HXT900 servo, although metal gear servos might be best for at least the two shoulder joints (heavy loads).

Ken, I still say Parallax ought to sell an arm kit like this. Sure would look great on top of an AB or S3!

https://www.facebook.com/Gearbestshopping/videos/2194834950840835/
"When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

- Pablo Picasso

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  • 6 Comments sorted by Date Added Votes
  • Or get this metal kit (no servos) for $24. 6-axis, includes ball bearings. https://www.ebay.com/itm/US-6-DOF-Aluminium-Mechanical-Robotic-Arm-Clamp-Claw-Mount-Robot-Kit-Black-47cm/192622166077

    This beast definitely needs metal gear/shaft servos for the high-load joints.
    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • wmosscropwmosscrop Posts: 278
    edited October 21 Vote Up0Vote Down
    erco wrote: »
    Pretty sure the four 9G servos are not included

    The servos are shown in the included parts (4th picture). I'd wonder about their quality, though, at this price.

    Edit:The servos are included for $17.99 (select the size on the right).

    Edit 2: I just bought one (with the servos). I selected the "US express" shipping option, so I should get it in about 3 weeks.

    Tulsa, OK

    My OBEX objects:
    AGEL: Another Google Earth Logger
    DHT11 Sensor

    I didn't do it... and I promise not to do it again!
  • Yes, the servos are not included with the $13 option. If you get 4 9g servos for $5 more that's a pretty good per-servo price. But quality is hit-or-miss. I plan to use Hobby King's HXT900 servos, they have a great reputation and are not expensive at $3 each now. Servos in this arm will be under a big load, so I like to build in the best quality I can from the start.

    "When you make a thing, a thing that is new, it is so complicated making it that it is bound to be ugly. But those that make it after you, they don’t have to worry about making it. And they can make it pretty, and so everybody can like it when others make it after you."

    - Pablo Picasso
  • OK, got the arm on Friday, put it together over the weekend, in between several sessions making wood crafts for my wife to sell next month.

    The good:
    * The parts are sturdy and very well-finished (I didn't have to remove any burrs, but I did spend quite a bit of time removing the protective paper.
    * Extra screws and nuts are provided.

    The bad:
    * Instructions are very poorly done. Instead of diagrams there are pictures. The arm assembled in the instructions is made of a translucent plastic and makes it very difficult to figure out which part is which in some of the illustrations. Not to mention the very skimpy text.
    * Some of the parts provided are almost mirror images of the the parts in the instructions. Lots and lots of fun figuring this out!
    * Most of the parts go together by threading a screw into a part. Unfortunately, quite a few of the parts that were supposed to have the smaller holes necessary for the treading instead had the larger (pass through) holes. I ended up using quite a few of the extra parts (with some nuts I had on hand) to complete the arm.
    * As designed, the entire arm is supported by the servo gear. This causes multiple problems (severe oscillation, etc.). I modified the arm to slide on the base, which seems to fix the issue.
    * The arm, even without lifting anything, appears to be too heavy for the two positioning servos (very jerky operation even when slowly ramping the servos). I have verified that there are no binding parts.

    It took me about 4 hours to assemble.

    My recommendation: you get what you pay for. Spend some extra money and get a good arm. For my project this will suffice.

    Walter

    Tulsa, OK

    My OBEX objects:
    AGEL: Another Google Earth Logger
    DHT11 Sensor

    I didn't do it... and I promise not to do it again!
  • eBay always has good deals on open box Dynamixel AX-12A actuators. Make an offer here for $100 and I bet he will accept (I've done it once with this seller).

    https://www.ebay.com/itm/Robotis-Dynamixel-AX-12A-Motors-6-Pack/262722105220

    That's $16 per actuator, excellent functionality, and very easy to use. You will need the connectors, and it doesn't hurt to have the programmer. That puts the price closer to $25 per actuator, still a good deal IMO.
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