Accelerometer, that tiny workhorse

The accelerometer chip (1 x 1 cm)

The accelerometer chip (1 x 1 cm)

Accelerometers are wondrous little devices that offer boundless possibilities… as soon as you figure out a need for them.

For some time now, I have been thinking about a filament break detector for 3D printing. Filament comes in spools of 400m (1 kilogram) and they are usually hung on racks on which they rotate. The filament is fed to the printer via a small stepper motor turning a grooved feed wheel. If the filament breaks, or the feed wheel eats a notch into the filament, it will no longer enter the extruder, and the print fails. Usually the filament wire breaks if it has been exposed to air humidity for a long period – it is hygroscopic and becomes brittle.

The printers are not aware of the filament feed. There is no detector for smooth feed, and consequently any hitch in feed will fail the print. I have thought of making an optoelectronic feed detector that would shine a light on the filament spool and detect its movement, but that would require a striped disc to be attached to the spool, as well as the actual reading device installed on the rack. Then I thought of a mechanical device that would ride on the filament itself and detect its movement via rotating discs, but that soon turned out to be too complex. (more…)