A small, hapless printer

A small, hapless printer

A printer was purchased at the salvation army for around $7. I made sure this one had a stepper motor to it – most modern printers work off cheaper servo motors. Nevertheless, there are still a few relatively recent printers I saw using steppers.

Oftentimes it seems the servos in printers today are little more than cheap DC motors with encoders strapped on. The encoders themselves appear just to be optoswitches reading patterns off flimy transparent film. The transparent film rotates around with the motor shaft and periodically spaced dark patches cover up the optoswitch, thus registering a “step”. This makes me think a similar process could be adapted to produce more affordable printers – dc motors would be cheaper and easier to find than steppers, and you could completely bypass the need for costly stepper drivers. Still, this would be more a firmware project than anything, since existing firmware to my knowledge rides on the assumption there is one pin to encode a step and another for direction. You would also loose the automatic breaking stepper motors have when not activated. This might have to require an entirely separate project unto itself…


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