I'll be documenting my modifications here and updating it as I work through the changes. You can find the designs and assembly instructions here: https://github.com/ongdexter/ar3_hardware_mods
Joint Position Encoders
I've recently got my AR3 integrated with ROS (more details here) and as part of the process had to shift the J2 and J5 encoders to read joint positions directly. I have a significant amount of backlash and slip in J2, J3 and J5. J3 is not as big an issue as it is calibrated under tension. However, getting more accurate joint position measurements for J2 and J5 was necessary for planning in MoveIt.
I've designed adapters for mounting the J2 and J5 encoders directly on the joints.
They are both designed to be added on with almost no disassembly required - just removing a few screws. The re-wiring of the encoder cables may be a little more tedious depending on how neat you want it to be. These were done up to the best of my very limited CAD skills, and I understand that Chris is also working on a proper design, but I hope that they will be useful for anyone who wants an interim solution.
Inductive Limit Switches
I'm done repositioning the J5 limit switch to calibrate directly against the J6 bearing cap, which should be more accurate than using the belt carrier. I also took the opportunity to try out an inductive sensor, which I thought would be easier to position for the calibration angle than the mechanical switches. Having inductive limit switches will also help avoid cases of damaged or bent limit switches. It seems to have worked well so I'll eventually redesign and replace the other limit switches as well.
your j5 limit switch modification look great
Just done with repositioning the J5 limit switch. I also took the opportunity to try out using an inductive sensor as the limit switch. More details in the first post.
Nice work Dexter! And because you mounted it directly to the joint it will also make it easier to use absolute instead of incremental encoders which in turn make it possible to remove limit switches, less wiring etc. It requires a bit of modifications to the software but I think I'm up to the task.
It would be a nice addition to the "standard" AR3
Ps. Can you also upload the step files to your Github(or Fusion 360 f3d format if you used that to make the designs)? It would make it easier if I decide to use a different encoder with a different mounting pattern.