Hello,
there is something I do not quite understand abou the OpenFlexure.
■ How are the motors homed?, and
■ How to proceed if, e.g. while first installing and getting familiar with it, the focus is not found and the motors and associated mechanical parts are no longer on the default/unstrained position?
Looking forward to finally get my microscope running.
Thanks for offering this to the world!
Best regards
Mathieu
There is not an automatic way to home the motors in the standard software. You will need to move the motors until you see that the actuators are centred.
You can tell that the actuator is centred when the hole in the casing that you put the brass nut in through, lines up with the nut slot in the internal actuator column. For the x-y actuators you can also look at the leg ‘ladders’ for the stage, which should be upright.
For the z-axis you can only see by looking at the nut slot, so try on x-y first to see how far to move, and what it looks like when the internal column is too high or too low. You will need a lot of steps to see movement, the motors are ~4000 steps per turn, and geared a further x2 to the actuators. It can be easier to unscrew the motors and turn the large gears by hand, you can feel if you turn the wrong way and get to the end of travel, and you can turn more quickly. Then replace the motors.
Once you have the stage physically centred, press the zero coordinates button in the navigate pane. This sets the step coordinates to zero. The number of steps moved is remembered when the microscope is powered off, so moving to x=0, y=0, z=0 should return to the physical centre (as long as you do not press zero coordinates by mistake when the actuators are not actually centred 
)
If you are having difficulty focusing, what optics are you using? Can you post a picture of the optics in the microscope, with the z-actuator centred.