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Who Needs a $300 Robot Arm? — Parallax Forums

Who Needs a $300 Robot Arm?

ercoerco Posts: 20,256
edited 2014-11-15 02:46 in Robotics
You do! Win it and send me my dollar for the tip.

http://www.ebay.com/itm/INTELITEK-ESHED-SCORBOT-ER-III-3-ROBOT-ROBOTIC-ARM-AND-CONTROLLER-/290737319032?pt=BI_Robotics&hash=item43b14b6c78 $300 Scorbot free ship
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Comments

  • photomankcphotomankc Posts: 943
    edited 2012-07-02 20:32
    Looks like the arm we used back in HS in the robotics lab! Those suckers were fun. Just need the conveyor belt, turn table and an assortment of wax blocks and you are ready to get busy doing nothing productive but having a blast doing it. ;)
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-07-02 20:48
    Any guess on how much that thing could lift?

    I'm still, sort of, looking for an arm that can lift quart canning bottles full of water.
  • photomankcphotomankc Posts: 943
    edited 2012-07-02 20:59
    Found this:


    The Scorbot ER-III is a JAR (Jointed Arm Revolute) robot which means it's movements are somewhat similar to that of the human arm. The ER III has three axes of rotation and five degrees of freedom. These degrees are illustrated through the movement of different parts which are:
    1) Base- lower part of robot which rotates about the y-axis.
    2) Shoulder- connects to the base by way of a joint which rotates about the x-axis.
    3) Elbow- connects to the shoulder by way of a joint and also rotates about the x-axis.
    4) Wrist- this portion is connected to the elbow and gives the robot its final two degrees of freedom. It is capable of rotating as a human wrist would, wrist roll. The wrist is connected by a joint along the x-axis which allows it to flex up and down as a human wrist would, wrist pitch.
    5) Gripper- this is end effector attached to the wrist and is capable of opening and closing. It emulates the action of a human using his/her index finger and thumb to grasp an object. This robot is powered via an electric motor.

    Robot Specifications:
    Mechanical Structure: Vertically Articulated, 5 Axis PLUS Gripper = 6 Axis; Support for 2 additional axis (Conveyor, rotary table, etc); Controller supports simultaneous control of all 8 axis

    Working Envelope:
    Axis 1: Base Rotation 310 degrees
    Axis 2: Shoulder Rotation +130 Degrees / -35 Degrees
    Axis 3: Elbow Rotation +- 130 Degrees
    Axis 4: Wrist Pitch +- 130 Degrees
    Axis 5: Wrist Roll Unlimited
    Axis 6: GRIPPER Open/Close + Measurement of gripper opening
    Maximum Working Radius: 61mm (24.4")
    Gripper Opening: 75mm (3") without rubber pads - 65mm (2.56") with rubber pads



    <<<<<<<Maximum Work Load: 1kg (2.2 Lb)>>>>>>>



    Transmission: Gears, Timing Belts and Lead Screw
    Actuators: 6 DC Servo Motors with Closed-Loop Servo Control
    Feedback: Optical Encoders on All Axis
    Hard Home: Fixed Reference Position on all Axes
    Repeatability: +- .05mm (+- 0.02")
    Maximum Speed: 330mm/Sec. (13"/Sec)
    Weight: Robot Arm: 11kg (24 Lb) - Controller: 5kg (11 Lb)


    With a little Tim-the-Tool-Man "more power" I'll bet that could be increased a bit.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-07-02 21:10
    Thanks for the info photomankc.

    I need it to lift about 1.3kg. I don't think I want to try to use an arm that can barely lift the load.
  • photomankcphotomankc Posts: 943
    edited 2012-07-02 22:46
    Yeah, the 4U model has something like 4.6lbs, but this aint that. Takes me back in time a bit though ;)
  • ercoerco Posts: 20,256
    edited 2012-07-03 08:19
    Rated lift is usually determined at the outer diameter of the reach envelope, where the long arm links are all horizontal. That's a worst-case scenario, putting max stresses on the shoulder joints. If you're able to avoid the outer extremes and stay inside a smaller work envelope, you reduce the moments significantly can safely lift more weight.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2012-07-04 12:50
    I'm going to keep my eye on this arm. I think it's worth $300 to me but not much more.

    I found a maual online for it, but I haven't found anywhere that sells parts. I worry about one of those belts breaking and not having an easy way of replacing it.

    Do any of you happen to know if there are replacement parts available for these things?
  • ercoerco Posts: 20,256
    edited 2012-07-04 19:30
    Duane Degn wrote: »
    Do any of you happen to know if there are replacement parts available for these things?

    Wouldn't you rather wait and be surprised? :)

    You better bid before I do, Pal!
  • ercoerco Posts: 20,256
    edited 2012-07-05 06:56
    If you simply can't wait for this auction to end, here's the same robot (BIN) for $1035 shipped. :)

    http://www.ebay.com/itm/140777327322?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649
  • ercoerco Posts: 20,256
    edited 2012-07-10 15:04
    Duane: here's another one 4U... http://www.ebay.com/itm/TeachMover-Microbot-Robot-Arm-parts-repair-robotic-pendant-/150852961295?_trksid=p4340.m1850&_trkparms=aid%3D222002%26algo%3DSIC.FIT%26ao%3D1%26asc%3D11%26meid%3D517536426615565380%26pid%3D100011%26prg%3D1005%26rk%3D2%26&autorefresh=true
  • ercoerco Posts: 20,256
    edited 2014-10-06 14:27
    Two interesting new (to me anyway) robot kits on Ebay:

    4-axis arm (not sure which one is the axis of evil): http://www.ebay.com/itm/DIY-4-Axis-Servos-Control-Palletizing-Robot-Arm-Model-for-Arduino-UNO-MEGA2560-/351150915118

    Gripper: http://www.ebay.com/itm/Small-robot-arm-Kit-with-MG946R-Servo-for-robot-lovers-/371157782012
  • Martin_HMartin_H Posts: 4,051
    edited 2014-10-06 15:43
    That palletizing robot arm is pretty sweet.

    I've been thinking about grippers lately. There's a huge amount of low end stuff with too much play and have a hard time griping. I suspect that the higher tolerances required for a better gripper would driving the price and wouldn't have a market.
  • ercoerco Posts: 20,256
    edited 2014-10-06 17:19
    Yessir, agreed. Arm looks very nice.

    Gripper has a nice profile shape, but it's quite thin, especially at the pickup contact spot, might be finicky. It's probably laser cut from one layer of something, IMO they should have attached more material at the pickup spot to make it wider for better consistency. I don't think a better gripper would necessarily break the bank. Doing it right/better doesn't have to cost more. But if you're the only/first guy doing it right you might be able to charge more.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2017-03-10 00:54
    I also liked the palletizing arm.

    Is that enough "on topic" discussion that I can now hijack hitchhike with this thread?

    I purchased one of these pan and tilt gizmos from ICStation.

    2537.JPG

    The reviews were kind of entertaining. They were expecting instructions and for the servo horns to fit without having to do any "hacking"? Fortunately, I've purchased enough of this sort of stuff to know what to expect and I was pleasantly surprised with how well the pan tilt gizmo worked.

    The first few seconds of the video below show the device in action.



    Most of the video (almost 11 minutes!?) is my attempt to explain how the parts go together.

    I'm pretty sure the servo tester being used in the video is the you gave me erco.

    Not really a "robot arm" but I thought it fit better in this thread than the pan and tilt laser tacker thread (though it would make a nice laser tracker).

    I'm wondering about getting a couple of more of these. I'm thinking two of them could be used to control the eyes of my Halloween Hex.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-10 14:07
    I shouldn't be surprised, but these are also on ebay. $2.46 shipped is the best I've found so far.
  • ercoerco Posts: 20,256
    edited 2014-10-10 19:14
    $2.46? Sold! Thanks pal.

    You're not the only one slamming servos and driving them with a servo tester. Just last night I finished installing 3 servos and 2 LEDs in my business partner's "Robobunny" 3D printed prototype for an upcoming trade show. Just have to build & program the controller board to fit inside. A few new tricks on this one. Lipo powered, I dissected a 7.4 pack into two 3.7 cells, just needed one. USB charging via one of the Ebay China charger modules. First look, using a servo tester:
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-13 19:01
    I just ran across this $55 robot arm at Adafruit.

    attachment.php?attachmentid=111443&d=1413252207

    I think those are little mini servos. I'm not sure what this arm could pick up but it looks cool.

    I think I like the one erco found in post #12 better.

    $_12.JPG

    IMO, it looks like it could to some useful work.
    RobotArmAdafruit.PNG
    950 x 703 - 819K
  • jdoleckijdolecki Posts: 726
    edited 2014-10-18 09:40
    I have 2 arms for sale. 150 for arm alone and 250 for arm in case with power supply and teach pendent with a cd of software.

    thanks john

    $(KGrHqR,!qgFI8lrR88zBSSeLcunyw~~60_35.jpg
    $(KGrHqR,!qgFI8lrR88zBSSeLcunyw~~60_35.jpg
    300 x 224 - 20K
  • rosco_pcrosco_pc Posts: 464
    edited 2014-10-19 23:40
    Erco might br interested in this: http://hackaday.com/2014/10/19/robot-arm-you-can-build-at-home/
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-25 19:53
    erco wrote: »
    $2.46? Sold! Thanks pal.

    It turns out these $2.46 devices are even better than ICStation's $5.59 version.

    The ebay device included servo horns to match mechanism's molded recesses.

    I decided to make a full fledged build video for the ebay device.

    The battery in the camera died as I was making the video so it's in two parts.

    Here's part 1.

    Here's part 2.

    I've also posted these videos on Let's Make Robots.
  • ercoerco Posts: 20,256
    edited 2014-10-25 20:11
    Genius, Sir Duane! Thanks for the videos. I shall endeavor to assemble mine this weekend.

    As for the dead camera battery, ROFL. Everyone suffers from that, no matter how tech-savvy or smart they are. Come back in 20 years when we have cold fusion and hover cars. Dead batteries will still plague mankind.
  • ercoerco Posts: 20,256
    edited 2014-10-25 21:30
    $2.33 Duane, it's hoarding time! http://www.ebay.com/itm/Aircraft-FPV-PT-Pan-Tilt-Camera-Platform-Anti-Vibration-Camera-Mount-Kit-/390868573362?pt=Radio_Control_Parts_Accessories&hash=item5b01951cb2

    BTW, I assume your Halloween Hexapod is all finished since you're busy panning and tilting over here just 6 days before Halloween?
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-26 08:09
    erco wrote: »
    $2.33 Duane, it's hoarding time! http://www.ebay.com/itm/Aircraft-FPV-PT-Pan-Tilt-Camera-Platform-Anti-Vibration-Camera-Mount-Kit-/390868573362?pt=Radio_Control_Parts_Accessories&hash=item5b01951cb2

    I notice neither your $2.33 link nor my $2.46 link show the two black servo horns. These black servo horns make the device much easier to use with HobbyKing's HXT900 servos.

    Since the $2.46 seller included these black servo horns, I ordered four gizmos from them.

    If you purchase any from the $2.33 seller, let us know if they kit comes with black servo horns.
    erco wrote: »
    BTW, I assume your Halloween Hexapod is all finished since you're busy panning and tilting over here just 6 days before Halloween?

    I plan to use the panning and tilting with the Halloween Hexapod. I'm hoping to use the inexpensive LED arrays as eyes and I plan to mount the arrays on these pan/tilt gizmos.

    I need to update the Halloween Hex thread and confess to making a bad PCB. My design is a Prop killer. I'm pretty sure the power or ground traces are such to cause current to flow through the chip which quickly destroys the PLL circuit. I'll probably end up using a QuickStart with my little servo extension boards to control the Halloween Hex.

    I'm still trying to figure out where to place all the electronics so there's a spot for the candy bowl. I hope to have this part figured out by the end of the day.
  • ercoerco Posts: 20,256
    edited 2014-10-26 15:47
    That pan/tilt is very sweet, Duane, simple to assemble (per your fine input), looks good and works great. The perfect size to build a third laser tracker, this one's for for Ken. Two more pan/tilts ordered.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-26 17:51
    I just noticed the black servo horns do need to be modified a bit after all.

    The black horns are too deep inside and end up binding against the servo when they're tightened down.

    It looks like half a millimeter of plastic needs to be removed from the part of the horns which mates with the servo.
  • ercoerco Posts: 20,256
    edited 2014-10-26 22:01
    On the pan or tilt servo? My tilt servo is binding somewhat, I thought it was the tight fit of the pivot.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-27 08:11
    erco wrote: »
    On the pan or tilt servo? My tilt servo is binding somewhat, I thought it was the tight fit of the pivot.

    I think both the pan and tilt servo horns are too deep for the HXT900 servos but the tilt servo's horn is much worse than the horn for the pan servo.

    I noticed the tilt's pivot hinge is pretty tight but I don't think it's so tight as to cause a problem.

    The tilt mechanism was hard to move when the servos were off and as soon as I loosened the servo horn's screw the tilt part was much easier to move.

    It looks like one may be able to modify the horn in situ. In fact it's probably the best option. If removing the protruding section of the servo horn from the tilt mechanism doesn't work, then some sort of spacer may need to be added inside the servo horn to keep the servo from binding with the mechanism.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-27 08:32
    Duane Degn wrote: »
    It looks like one may be able to modify the horn in situ. In fact it's probably the best option.

    Brilliant idea Duane. The plastic piece which connects with the servo horn makes a nice jig to hold the horn while shaving the extra plastic away.

    I tried this on my mechanism I have not yet assembled. It probably wouldn't have been so easy if I had other parts of the gizmo still attached.

    I'm trying to figure out if there's a problem with just not tightening the screw holding the servo horn in place. If I loosen the screw, the mechanism moves without binding. I'd be very surprised if the screw comes out.

    Can you think of a reason why one shouldn't just loosen the screw?

    I suppose it would depend a lot on where and how the device is used. A loose screw may be fine on a ground robot but if the device is used in an aircraft of some sort, then modifying the servo horn is probably the best option.
  • ercoerco Posts: 20,256
    edited 2014-10-27 22:10
    Yup, I just removed the whole pivoting assembly and hand sanded the portion of the horn that stuck above the bracket. In situ, if you will. Worked like as charm. Only the tilt servo was binding for me, I didn't have to adjust the pan servo, so I didn't even look at it.

    Don't just loosen the screw, that's a half-Smile solution and you may strip the servo splines. You want a tight screw to keep those parts together, trust me.

    These are nice. I'm hoarding, oops, ordering two more tonite. I'm working on an IR scanner now and the initial tests look good.
  • Duane DegnDuane Degn Posts: 10,588
    edited 2014-10-28 09:47
    erco wrote: »
    Only the tilt servo was binding for me, I didn't have to adjust the pan servo, so I didn't even look at it.

    I reexamined the pan servo in my unbuilt kit. The horn does not bind. There's a small gap between servo horn and servo as there should be.

    You're correct about just the tilt horn needing to be modified.

    I'm looking forward to seeing what you do with yours.

    Did you order from the same seller? I ordered four more from the "liwanpingpainter" since I knew his kits included the black servo horns.

    I'm still waiting for two I ordered from "ouyou2010".

    In hindsight, I think the first step to assembling these gadgets is to install the servo horns. Another change I plan to try is to use the mounting screws which come with the servos to mount the tilt servo rather then the machine screws.
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