The title might piss off a lot of engineers. This is the hardware-equivalent to someone saying everyone should build their own compilers (effort and difficulty don't pay off upfront). For broader context, motor controllers mix high current power electronics, fast switching, and sensitive sensing on one board, so literally any small mistake can cause heat, noise, and failures. You're also juggling electrical, thermal, and control constraints while keeping EMI, switching behavior, sensing, and protection stable in a tight space. (Although if your design layout is great you don't need much protection). And you still have to deal with firmware, tuning, and debugging. So yes, it might not make sense initially. But here's why I think more people should do it anyway.

For starters, designing your own motor controller PCB gives you full control over the electrical, mechanical, and performance characteristics of the system. You can choose components, sensing methods, protection, and form factors that match the exact motor and application, which improves efficiency, responsiveness, thermal behavior, and reliability. If you're building things at scale, it also significantly lowers your costs long term, reduces supply chain risk, and gives you access to much richer data for diagnostics and control.

From a learning perspective, building a controller forces you to understand the power electronics, sensing, firmware, and physical constraints of the system, which makes you far better at building compact, high performing, and scalable machines.

For the work we're currently doing (ask me about it), all of the XYZ axes run stepper motors, so we needed a controller that could handle position control accurately but also interface cleanly with the rest of the system (which is also designed from scratch). Since we're using steppers, which have two phases, you drive current through each coil in a controlled pattern to optimize the magnetic field direction for peak performance (field-oriented control).

In brushless motors you'll typically see twelve or so stator slots, but steppers have fifty, which pushes you toward high-resolution encoders for good estimation on electrical angle. Also, high switching frequencies (around 100 kHz) are needed to have low current ripple, which is why most people don't do FOC on steppers, despite it being better. Most people are scared of power with high frequency designs, but with good board layout and EMI minimization through low inductance loops etc, it's actually not that big of a deal. The board communicates with the rest of the system over RS485 for a fast, simple, and noise-immune bus. Making a custom controller allows you to not only run FOC, but also change the control parameters based on operating point and machine characteristics. One example of that is adding virtual damping for chatter on all axes. Our controller also interfaces with extremely high accuracy position sensors on the gantry (which we're also designing) which gives closed loop feedback after the belt and ball screw transmission at high bandwidth.

If you made it this far and actually found this interesting, maybe you should work with us.

12/02/25