When you first get your Ember you might have issues with one of these sensors. Errors during calibration at the factory can cause problems from always detecting a jam to slowly drifting until the part is no longer over the build area to crashing the resin tray into the build head or worse your part! This Instructable will show you where the rotation homing and jamming sensors are and how to adjust them to their correct positions.
Step 1: Remove the Front Panel
There are two M3 button head machine screws on the side. Remove these first.
Two plastic screws with no. 10 torx head on the bottom. Remove these second. You can likely use the 2mm allan key to take these out if you're gentle.
Step 2: Raise the Jamming Sensor to 2mm Above the Middle Plate
The jamming sensor is on the right side of the machine. It looks like a plastic threaded rod with two large nuts locking it in place. It is just a reed switch that checks for a magnet on the bottom of the resin tray support plate. It needs to be placed 2mm above the middle plate as shown in the picture. If you have problems where Ember has false jams after adjusting the sensor it should be replaced. If obvious jams go undetected you can try lowering it, but there isn't a very clear cut way to know how low besides trial and error during a print. The 2mm mark should detect jams within Ember's tolerances for almost all sensors.
Step 3: Calibrate Homing Sensor
The homing sensor is the same reed switch as the jamming sensor. It is on the left side of Ember and adjusting it to the right height is a little more nuanced. To easily adjust the sensor, you'll need firmware version 2.0 or later as that allows access to low level motor commands. First ssh into Ember, you can do this either over a USB cable or over your network. If you choose USB you'll need to install Ember's USB drivers, you can find them here
Connect to Ember using a USB cable if ssh'ing over USB. To ssh into Ember follow steps 2-4 of this Instructable
If you're ssh'ing over network replace 192.168.7.2 with the IP address of your Ember. From the Ember command prompt (root@ember:~#) you'll enter the following commands.
zee I H
to home Ember and
zee I rs8 rj100000 RV60000 W
to rotate Ember's build tray 60 degrees. The process is
1. Adjust sensor
2. Home Ember
3. Rotate 60 degrees clockwise
4. Check for alignment between the resin tray platform and optical path
5. Repeat until the paths are aligned
If the tray is over rotating when it returns the sensor needs to be lowered. If the tray isn't rotating far enough (or rotates in a whole circle) the sensor needs to be raised.
Note: There are two magnets under the resin tray platform. One on the left for homing and one on the right for jam detection. If you enter the homing command when the magnet underneath the resin tray platform on the left is past the homing sensor, Ember will home to the magnet intended for use with the jamming sensor. To solve this just rotate the tray counter-clockwise manually until it is past the homing sensor and then issue the homing command again. For a complete list of low level motor commands check out this page