Bolt and Screw Sorter Built From Recycled 3D Printer Identifies Parts With Camera and Scale

An enthusiast known as , who takes apart and repairs hardware, accumulated a huge collection of mixed bolts and screws over time. To bring order to this chaos, he built an automatic sorting system that, while presented as a proof of concept, is not limited to fasteners — the device can group any small objects.

Here is how it works: the mixed parts go onto a wide conveyor belt, from which they roll down a chute a few at a time onto an illuminated platform. A camera is mounted above it, and machine vision determines the size, shape, and orientation of each screw. A robotic gripper on a gantry then picks up the parts one by one, separating any that clump together, and moves them to a drop-off cart that releases the object into a bin with matching items.

The core of the build is a repurposed Ultimaker 3D printer, whose hot end has been replaced with a gripper that can raise and lower. Servos and steppers are controlled by an ESP32-WROOM board, while a piezo sensor detects screws falling off the belt. The overhead camera is an ESP32-CAM adapted to accept M12 lenses so it can focus on the platform.

An additional feature lets the system weigh a picked object by placing it on a movable inspection platform, which can optionally position it under a USB microscope for a closer look. Everything is run by a nearby PC, offering plenty of flexibility.

Once all the screws and bolts in a shop are sorted, it makes sense to sort the nuts as well. The author invites readers to share ideas about what other objects would be useful to classify with a system like this.