With my eBay RAMPS 1.4 package came 3 optical end stops. The end stops are used by the printer to the software the end (or beginning) of the corresponding axis is reached. Optical endstops are triggered when an obstacle (a so called flag) blocks an invisible beam of light between the two black ends of the endstop. The motor on the corresponding axis will then stop.
A RepRap Prusa I3 printer comes with 3 endstops, one for each axis. They are placed on the axis close to the motor. This is the home position of the printer, if the home button is pressed on in the software the printerhead will move towards this position.
First, you have to mount the endstops on the printed parts.
3 x M3 nut
1x printed part
1 x M3 x XX bolt
2x M3 x XX bolt
As before, you have to melt the nut into the printed part with a soldering iron (at least I did).
If needed, clear the hole of molten plastic.
My optical endstops came with a nice plug and connector. The endstops have three connectors:
V = + voltage
G = Ground
S = Signal
I had to lengthen the wires in order to attach them to the RAMPS board.
Here, I soldered the yellow wire to the signal output, the other ones (black and red) are ground and + respectively.
Place the Y-Axis endstop at the back end of the Y-Axis carriage.
The endstop needs a flag to be triggered. I used a angle profile (a leftover of my aquarium) and glued it on the back of the heated bed board.
Here a view of the flag and the endstop, with the Y-Axis table turned around.
The endstop of the X-Axis will be placed at the left side of the X-Axis carriage. Again, you need a flag to trigger the endstop.
Here, I glued the flag on the extruder main body.
One disadvantage of using opto endstops is the use of a proper flag that can be adjusted in close enough steps to level the heated bed with the extruder. With mechanical endstops a screw is used to trigger the switch, but this screw won’t fit between the sensor of the opto endstop. So you have to come with some other soltution.
I used two aluminium angle profiles and two springs and mounted them as below:
You now can adjust the distance of the hotend to the bead by sliding the Z-Axis opto up and down the rod, and make micro adjustments with the two screws on the opto-mount.
I cut two 10 mm aluminium strips and mounted them on the X-Axis motor, to be used as a flag for the Z-Axis opto.
Now proceed to chapter 10: The Hot End