Jan 24

J2 Motor Support causing Motor's Gearbox Deformation


When performed first test run of AR2, suddenly J2 motor did not move and It appeared as the gear is disconnect with "crack crack" sound.


Below is the video link to show the problem where gear is not turn when motor is on.


Spending couple of days via email with OMC technician to trouble shoot and root cause finding. The technician concluded that the M6x20 cap screw is causing gearbox deformation which might be irreversible. Below is the photo what OMC technician email me:-



I decided to change the way J2 Nema23 motor screw on J2 Motor Support. Below is the photo example:-


By using 4 M4 cap screw and washer between J2 Motor Support and J1 Platform.


AR2 has been running 6 hours (yesterday) and 4 hours (today, now still running) without J2 motor gearbox problem, I will update if problem keep come back which J2 motor gearbox deformation already irreversible and have to replace with new one.


M6X20 cap screw and locking might not needed in aluminium structure which original is for 3D printed.








Thank you for the detailed feedback. I will add information to the manual to only tighten M6 screw enough to secure gear box radially but not overclamp or deforms planetary gear housing.

Jan 24

After running AR2 for another 4 hours. The J2 motor gearbox problem does not not come back (touch wood). I did not use M6X20 cap screw at all. I will continue perform other test and hopefully this will not has any impact on AR2 when it is on production operation.

New Posts
  • Hi Guys, As I have been having so much fun with my AR2 Robot I just wanted to share a little more of my build. A super big thank you to my Buddy Chris for the awesome amount of work he is put into this project I am excited to say that I have ordered everything to build the newer AR3 robot. I am hoping to participate more in the Forum with the progress of my new build. Here are a few links to video clip of my AR2. https://photos.app.goo.gl/4kotsAAKtzRW9gxPA https://photos.app.goo.gl/NwNrMnFB1ekGHJFv9 https://youtu.be/t4HPfhZHC2c
  • Actually this is not my own build, but i cant ignore it ) And i planning to buy kit, but still looking for g-code postprocessor.
  • I'm working with a small group of students to pilot a new education program called Robot Inc. We're challenging students to start their own robotics startup. We have a thriving First Robotics program but I've always been disappointment by how much money and effort goes into those competitions only to build a robot that really doesn't do real work. Additionally the robots are always very similar year to year and are remote controlled instead of autonomous. If that same effort and funding could be going to building a real robot that does useful work, then I'm sure we can find willing buyers. We're using the AR2 to give the students real robotics experience before they create their own custom robot. This robot was 3D printed on a Uprint FDM printer. This type of printer creates almost solid parts and is highly reliable. Additionally, we laser cut the covers out of 1/8" black acrylic The cover support for J2 was 3D printed as one piece on a Mark Forged Onyx printer with kevlar reinforcement to give it a bit more rigidity. We still have some adjustments to do as well as clean up the wiring but its looking pretty good. We're having fun getting used to the software. One cool upgrade would be to use Dynamix servo motors with feedback. If those were used then you could "teach" the arm by physically moving it to the position you wanted then teaching it that position. You could also then incorporate crash detection. It would definitely increase the cost substantially but could be a worthwhile improvement for the pro users.