I am happy to report that I have managed to “wear out” a pen arm servo. Tried the excellent “Stipple” program yesterday and “fine tuned” the eggbot parameters to manage about four points per second as stated possible in another post on the forum. Midway through the plot of 9400 points the servo went “belly up” and failed to move. Plugging my spare servo (with the plot still going – pen down all the time) verified that the servo was bad, the spare moved like it was supposed to. “Dissecting” the failed servo I found the motor to be bad – helping it start by turning it by hand would have it moving for a while. My servo might work a little “harder” than usual as I have a rubber band to provide some “extra” down-force on my pen arm for my ball point pens to work reliably.
Anyone else plotted enough eggs to wear out a servo?
We have, ourselves, never managed to wear one out in our demo units, or through anything resembling normal use. (We did manage to kill one by driving it directly at 9 V for a while…)
But, thinking about it for a moment, we would actually expect a reduced lifetime because of the way that you’re using it. As you say, because of the rubber band, the motor is having to work harder than it usually does. You might see if you can reduce the force that it needs so that the next one lasts a little longer.
I rather trade “wearing out” a servo every four years for high quality plots. The servo is a “low cost” item anyway, some of the pens I have experimented with costs more. Having a servo and a few other “bits & bobs” in spare comes in handy.