Re:Jello 3D Printer (2013)
by londons_explore on Thursday March 18, 2021 @07:48AM
(#26501680)
Except that a CDROM wants to be able to seek quickly (say 100 milliseconds) while also read a disc at 1x speed (taking 75 minutes).
Having a DC motor which can run smoothly across 5 orders of magnitude is pretty much impossible. Stiction will always be more than 0.05% of the motors power output.
You therefore have to use a "go-stop" approach based on laser feedback instead.
Re:Jello 3D Printer (2013)
by DoingIsLearning on Thursday March 18, 2021 @08:33AM
(#26501979)
'Stiction' - the static friction that needs to be overcome to enable relative motion of stationary objects in contact.
As a non-native english speaker I assumed that was typo and had to search for it. I will also assume I wasn't the only one.
Besides cost, the track on an optical disc runs in a spiral, and thus the continuous motion of a DC motor is advantageous because the feedback loop is adjusting the linear velocity of the head instead of its absolute position, whereas a stepper motor would have to make discontinuous jumps. This helps tracking performance and decreases noise (both electrical and acoustical.)