Optical Endstops

I am waiting on solder paste, but in the meantime I soldered all of the optical endstops because they don’t require the hot plate reflow method.

The printer has a stepper motor for each axis- X Y and Z. Each stepper motor runs along a metal rod. A problem that might arise is this: how does a stepper motor know when it has reached the end of the rod? If it goes too far, it might damage some of the hardware, or maybe even the motor itself.

…Which is where the endstops come in. There is an optical endstop for each end of each axis (two ends per axis times three axes equals six endstops). It works by shooting a beam of light into a light sensor. As long as the light sensor detects the light, everything is fine and it sends a signal equivalent to OK.

However, the printer is constructed in such a way that when a stepper motor reaches the end of the axis, the beam of light is broken. As soon as the light sensor stops detecting the light, it sends a message out. The motherboard interprets this message as STOP.

Pretty clever, right?

endstops, completed

The black component with two rectangular sections (NOT the RJ45 connector) is the sensor. One of the rectangular sections contains a light and the other contains the sensor. Putting anything between those two sections cuts off the beam of light.


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