Endstop question

I'm sure this has been considered before, but why are the end stops optical? Is it more precise that way, or less expensive then a simple electromechanical system?

Is there any reason why having a whisker switch or electrical contact wire would be worse? I should think that it would be easier to use and less breakable if the end stop was just a bent wire that touched a contact plate, connecting the circuit.

What am I missing?

-Samuel

The optical endstops are reliable and cheap. I've found that they are also repeatably accurate to the limits of my system's resolution, viz, 0.102 mm

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Hell, there are no rules here - we're trying to accomplish something.

Opportunity is missed by most people because it is dressed in overalls and looks like work.

Thomas A. Edison