Mini Servo operated Claw Machine Claw Grabber

thingiverse

My goal was to build a claw machine, small enough for desktop use. However still large enough to be versatile. I am currently working on the rest of the machine, and will upload everything once complete. I tested a number of different designs, using screws and linkages to operate the claw. This version is by far the best I managed to design, it operates smoothly, is compact, and high strength. This design uses three bevel gears to tie the arms together. One of the arms is driven by a 9G servo to operate the claw. There is very little play in the claws. Overall I am very happy with the performance of this arm. And it would be ideal for small to mid-size DIY claw machines. Around 130mm tall (when claws closed). Opens to a diameter around 160mm, when claws open. I used a corona DS-919 servo. Gripping force is okay, but I think it could benefit from having a little more torque. If you want to try this, I would recommend a servo with higher torque. I'm currently considering using the corona DS939HV, however cannot verify weather this would work yet. If you do decide to try a different servo, consider that this usage has the potential to be hard on servos. Plastic gear servos are not likely to withstand being stalled out often, and will not last long. So I would stay away from HXT900, SG90, or any other cheap plastic gear servos. All parts were printed with a 0.2mm Layer height. 3 perimeters, and 20% infill. I used PETG, however other materials would also work. A hardware list is provided. You may also need some basic tools, knifes, small drill bits, etc. Most parts should not need to have the holes drilled out, with the exception being the servo linkage, which may need a bit of drilling to fit the 0.8mm wire, that attaches the linkage to the arm. Be careful to not drill completely through the servo linkage parts, as they are designed to hold this small piece of wire captive. When assembling, lightly tighten the screws and servo linkages, and then back off 1/4-1/2 a turn to allow the arms and linkage to operate freely. It is very easy to over tighten these, which will cause the claw to bind and not operate smoothly. So keep these screws loose. I recommend hot gluing the heads, or using some low strength thread-lock, to keep it in adjustment after testing. Try to not get any thread-locker on the plastic parts. The hole in the center is for mounting cables and winch cable to. I used a nut on the top and bottom, to stop it from backing out, and secured the cables to it with a zip tie. Here is a short video of the claw in action https://youtu.be/HIgzmmK-rGw