@Zach Allen Hi Zach, would there be any possibility of being able to speak with you directly? It's about your SushEngine project. Regards!

Hello Zach, I am anxious to know how the Sush project is going!

You have it in the Robot Arm assembly, it's from shaft 1 ", outside diameter 1- 9/16". The reference is 5909K36 of McMaster Carr, you can look on their website for more information. In Europe I have not found those dimensions exactly, the most similar is the AXK2542, which has a larger external diameter.

@Zach Allen The downside of Arduino is that it is mono thread (I do not know if it is well said in English). That it can not do two things at once, and its processing capacity is limited since it is a microcontroller, not a microprocessor. The idea of ​​the RPi is very good, what I do not know is if it will be able to work and manage the control of the engines and the directions and at the same time execute the python control software. All this has a problem, and that is that you should have waited to have it all complete to teach it, since now I am very nervous and anxious to see it work that way hahaha How much filling have you put to the print of the robot parts? Best regards

Wow, you're doing a huge job. My English is not very good, there are things that I have not understood well. With your Shusengine, what do you do is load the arduino control into a RPi? Do you eliminate arduino from the control part, as well as the drivers that Chriss uses in your project, no? I was talking to him about the possibility of using Arduino Due 32 bits and tmc drivers like those used in 3d printers. With the Shusengine theme, when loading the control in the RPi, would you also load the Chris control software for PC in the same RPi or should you continue using a PC to control the AR2? I'm waiting to start the construction of AR2 printed on PET-G too, you had to give horizontal expansion (I use CURA) to improve the tolerances of the bearings? Greetings and great work! I look forward to your progress.

@Chris Annin Wow, the people who use gecko drivers speak very well of them, but they are very expensive. Can the optocoupler solution be good or not fast enough for the PWM outputs? The drv8825 for the larger motor would fall short, you could use a tmc2260. These drivers are used in 3d printers and work quite well.

Could you load the arduino mega skecth directly into the arduino Due or do you have to make a new sketch? To be able to excite the drivers, since the drivers of the AR2 are excited with 4v minimum, could be used for example DRV8825 drivers, which reach up to 2.5A and use 3.3V as well, or could optocouplers such as 6N136 be used to make Relay between the Due to 3.3 and the drivers to 5v? The truth is that using a Due, the movements would be more fluid, as happens with the Delta type printers, the 8-bit arduino are a bit short in calculation speed to interpolate the axes.

And what have you done with the bearing 32009? have you ordered the 73 mm or have you modified the housing part of J1? The same thing happens to me with another bearing of mcMaster, of 1 "of axis and 1-9 / 16 it is impossible to find it. the most similar is the AXK2542. Maybe it would be good to make a European list of all the references, because if we buy it from the US the taxes of import are very expensives.

I think I read that you made the printed version in ABS. I'm thinking of doing it in PETG or in POM, which according to the POM is more resistant than ABS and suffers less wear. Perhaps with this material you can reach a payload somewhat lower than with aluminum, but more than 700gr. what do you think about that?

Thanks for your answer!