cookie-snatcher2 001Are cookies out of reach in your house? When I was a small kid, the top of the refrigerator seemed MILES away… until I built a robot arm out of toothbrushes, popsicle sticks, and cardboard to reach it for me!

I’ve upgraded my old idea to include a motorized linear actuator so you can see how real robot engineers create linear motion (back and forth along a straight line) from a spinning motor. The motor AND nut both need to pivot for the claw to work, so take special note as to how the linear actuator (the scissors-looking thing) is built.

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16 Responses to “Robotic Cookie Snatcher”

  1. birgitemramsey says:


  2. khansamahmood1 says:

    is it okay to use tacks instead of brass fasners

  3. It can get jammed if the nut isn’t able to rotate (which is why it’s mounted on the tack/brass fastener). Remove the nut and spin it freely on the shaft. Does it move smoothly up and down? If so, try again and make sure it can rotate so it doesn’t jam. Also send me a picture (, as I might be able to suggest a few things after seeing your project. 🙂 You can do it!

  4. Nancy Young says:

    dear Aurora
    I am have been working on the cookie snatcher and when I hold my jaws in my hands i can feel it trying to move but it is jammed.
    I have tried loosening the joints, but nothing has worked.
    could you help me??

  5. Kelly Mcguire says:

    Hi there,
    I wish there was a place to post picts! My daughter loved this project. She had so much fun putting it together and needed only minimal help- she was thrilled!

    The arm is so speedy we had to put a rubber band at the end of the bolt . This seemed to keep the nut from flying off!

    Thanks again!

  6. Sure – you can use rechargeable batteries, but it might not have enough voltage to illuminate the LED you get – most rechargeable top out at 1.2V, and most LEDs require 2.7V, so you might have a problem (2×1.2V=2.4V). While yours should work fine for most experiments, be aware that they have way more mAh than the cheap ones, so if they are accidentally short-circuited, they (and the wires connecting them) can get VERY hot. Theoretically, the batteries can also explode (though I’ve never had this happen). This is the main reason I suggest the cheap (low-current) batteries to start with.

    Hope this helps!


  7. Nicola Ainger says:

    Hi Aurora

    Just a question about batteries. know you said in an earlier build it was best to use the cheap kind of AA battery, but can we use rechargeable batteries safely? We have Ni-MH (2200 mAh) rechargeables that we use for all the kids toys so wondered if those are ok to use for these projects or should we get some cheap disposables?

    Many thanks


  8. Radio Shack – see the shopping list for this unit and you can find the order links online.

  9. Lorelei Grecian says:

    Hi Aurora, where do you get the motor, alligator wires, and AA battery cases?
    🙂 😀 😛

  10. jeremiah ryan says:

    Looks Fun!!!!!!!!!!!!

  11. If hot glue isn’t working, try epoxy or JB Weld. You can get the kind that cures in 5 minutes from the hardware store, and this will come in handy for the more advanced projects as well.

  12. Sonya Fiebig says:

    Hi Aurora,

    How long should the hot glue take to dry? I’m trying to attach the bolt to the gear on the hobby motor with hot glue but it keeps breaking off. We’ve tried roughing up the bolt with steel wool but that’s barely made any difference. What else can we use to make it stick?

    Thank you

  13. Sometimes the tack can be so perfectly smooth that the glue doesn’t stick very well. You can scuff up the tack with sandpaper or a steel file, and try it again, or use 5-minute epoxy or JB Weld (use gloves when handling so you don’t glue your fingers), but you might want to help him if he’s never worked with glue that requires a hardener before (just follow the directions on the box). The wing nut WILL stay attached if you use one of these after roughing up the surface. Don’t use crazy glue or other types of glue that require a tight-fit in order to seal – you want something that is thick enough to fill in the gaps and hold strong.

  14. Meredith Hutter Chamorro says:

    Hi, Aurora. My son has spent a long time on the cookie snatcher. It looks great, the wiring is all good, but the problem he is having is that the wing nut won’t stay glued at all! Should we switch to crazy glue or what, because the hot glue gun isn’t working?