Hi all,

I've been working with the AR4 robotic arm for a few weeks now and wanted to start a discussion about its use of stepper motors — both the pros and the potential areas for improvement.

As many of you know, the AR4 is a great open-source 6-DOF robotic arm, but its use of NEMA 17 and 23 stepper motors can lead to some performance limitations, especially under load or at higher speeds. I’m curious to hear how others are addressing or working around these issues.

Here are a few questions and observations:

Heat and Holding Torque: My motors get quite warm during long motion sequences. Have you optimized current settings or used active cooling?

Microstepping vs. Accuracy: What microstepping settings are you using with your AR4? Have you noticed a tradeoff between smoothness and repeatability?

Closed-Loop Stepper Upgrades: Has anyone tried upgrading to closed-loop steppers (e.g., from Leadshine or JMC)? Was the increased complexity worth the improved performance?

Payload Limitations: I’ve noticed joint 2 and joint 3 struggle under payloads over 500g when extended. Have you made any mechanical or electrical modifications to improve this?

I’m also curious whether anyone has considered converting the AR4 to servo motors instead of steppers, or even using integrated servos for tighter control and reduced wiring.

Would love to hear what modifications, firmware tweaks, or mechanical reinforcements others have tried.