Show HN: SmartRuler Pro – ESP32-powered motorized ruler with 0.5mm precision (opens in new tab)

My dad cuts window profiles in his workshop and I kept watching him measure, mark, and reposition by hand hundreds of times a day. So I built him a motorized ruler that moves to any position you tap on a tablet.

It runs on an ESP32-S3 over BLE 5.3, uses hardware-timed stepper pulses (RMT peripheral, no CPU jitter) to hit 0.5mm accuracy, and pairs with a Bosch GLM laser meter - point, measure, and the ruler moves there. No typing, no transcription errors.

You can also upload cut lists from a file or email and it runs each position in sequence - perfect for batch cutting window profiles where you need the same set of measurements repeated all day.

Open hardware: off-the-shelf linear rails, NEMA 23 closed-loop stepper, inductive homing sensor. Total BOM is about 470 EUR. I sell the firmware, app (Android + desktop), and a step-by-step build guide for 350 EUR.

Video demo: https://youtu.be/GCUHBiIs4Vk

Happy to answer questions about the build or the ESP32 RMT approach to stepper control.