I'm also having problems with the encoders. Although I used an earthed screen for all the encoders the signals are very noisy (at similar voltage levels to the ones you have recorded) and joint 5 only has an output on one of the two encoder outputs from it. I took the encoder off and had continuity between both of the encoder outputs and the corresponding teensy pins. Maybe this is a faulty encoder? By disabling the encoders I don't get collision warnings. I don't know whether to pursue this issue or just live with encoders disabled. I'm not sure that the encoders provide much value?

Thanks Chris, I thought that I was going mad. A while ago I did an interim update on my PLA, AR2 and upgraded to the high precision versions of the stepper motors/gear boxes. Out of interest I tried the AR2 (high precision) in the AR4 J2 and although the gear box looks externally identical to the new AR4 with encoder combo it appears to have less backlash? There do not appear to be any identifying marks on the gearboxes so I wondered if you knew if there are any differences? Once the robot is operational I can do a more representative comparison. Final question, is it possible to just upgrade the gearbox for J2? will the stepper motor shaft be compatible?

Having now looked at the AR3 instructions for J2. These are similar to those that I saw for AR4 before they "changed". I'm sure that the ones I was using were for the AR4 as the new spacing ring was included and the motor had a pre-fitted encoder?

I've just started upgrading my AR2 to an aluminium AR4. I had this same question re screen grounding. I've decided to provide a connecting wire to the screen section of the encoder wire bundle & decide later whether to ground or not. A section of screen which is ungrounded could act as an aerial? A screen grounded at both ends is not generally a good idea?

Thanks for getting back to me. I've now received the one in the link and it appears to have the ethernet chip fitted. Presumably this version will still communicate correctly over USB?

Hi Kstan, Thanks for your comments. Since my first mail I've done a bit more research and it looks as if it is possible to buy just the stepper motors (without gearboxes) with the dual shafts which are required to fit the encoders. In summary the most expensive motor with gearbox costs around £63, the motor on its own around £24. It looks as if most motors are available as dual shaft versions and I don't see why I can't retrofit them. The down side is that these motors will probably not have the additional holes required to bolt on the encoders (not insurmountable). I also read a posting from Chris which said that the improvements provided by the encoders (for an AR2 to AR3 upgrade) were probably not worth the expense. If I buy the AR3 motor/gearbox set and the six encoders I estimated this to be around £350 on-cost. Based on this I think I will just upgrade the 3D printed covers and wiring. Where I need to do some work is on the J5 movement as in my arm this has a lot of slop in its movement. I probably need to have a better way of tensioning the drive to this joint . It may be possible to provide feedback just for this joint which would be a cost effective improvement. Thanks, Keith