Coupler redesign

I think the coupler of the previous design is it’s most significant shortcoming on the mechanics in terms of getting good data.

Although I have used that print-in clover coupler on quite a few different builds, it is an over-constrained coupler and that has always bothered me a smidge.

And not just on a conceptual level, in many of those applications I’ve heard periodic loading of the motor that I’m pretty sure is due to the combination of misalignment and over-constraint.

I started with a proof of concept test print, shown in the model below. I printed it with small handles on each end, just to be able to manually attempt to transmit torque with an offset introduced.

Design Goals:

• I’d like the coupler to fit inside of a 30mm ID bearing. That would make it a ‘drop in’ replacement for the spider couplers I’ve been using.

• +/- 1 mm radial misalignment

• +/- 5 deg angular misalignment

• ≥ 1 N*m sustained torque capacity

I used the proof of concept design discussed above as a starting point, but I reduced the pin sizes to 3mm OD from the 5mm used in the initial test. The below image from the model shows the first attempt at a coupling that meets the above requirement to fit within the 30mm ID of the 6806 roller bearings I often use.