So you have upgraded your printer to Tinyfab CPU. It's time to make the most of extended features of the onboard smoothieware software. This time is the auto bed leveling for your uneven bed surface.
To use this feature you will need to install an additional sensor. There are a number of different type of sensors around. These includes the infrared, contact, laser, capacitive or inductive. They all have their pros and cons, this blog will focus on inductive sensor on the cetus 3d printer. Inductive sensor provides very good repeatable accuracy compare to other method even with external environmental variation.
Traditionally inductive sensor only operate on 6v-24v but now you can get 5v version which makes the wiring much more easier for the 3d printer world.
In this case we use a 12mm NPN normally open 5v inductive proximity sensor. The sensing distance is said to be 4mm but in reality this only valid if the sensing material is made out of steel. Most likely you will have an aluminium heatbed instead, this less metallic property will causes the sensing distance to degrade to 1-2mm.
Luckily tiertime has left a door sensor port available for use on the cetus mk1/2 mainboard but not so lucky is that the port has no soldered connector, so you will have to fire up your soldering iron and solder a JST XH 3pin connector. Electrical wise there is a pulled up input pin straight to the CPU, and there is a ground, jolly good.
So where is the voltage source? Unfortunately the door check port do not have voltage supply pin. So you have to swap the x-axis endstop with the door check port.
Anyway good news is , all you have to do is plug in to the correct port.
To be continued....