Polargraph Drawing Machine

Step 18 Finish configuring your controller

Start the controller again, and change to the setup tab.

Set:
machine width
machine height

entering the values you just measured, in millimetres.  Height isn't actually that important since it doesn't affect the geometry, but it does affect how big it appears on your screen, so make it accurate if you can.  You will be able to see the machine changing size on screen as you adjust these values.

You can also change the page width here, and the page position.  Unless you have a much wider machine than this, leave page pos y as 120 though.  

Other than that, page size and position is a purely visual aid to let you size your drawing properly.  You can centre the page horizontally with the centre page button.

The home point has a default position that is where you marked it on your board in the last step, that is, halfway across the top edge of your machine.  Click centre homepoint to reset if it goes astray, and you can set it to anywhere you like if you don't want it there (for whatever reason).

Now save properties again so you don't have to enter this again!

Advanced editing
If you are using different motors, or different sprockets, change:

• machine.motors.stepsPerRev: This is how many steps your motors have per revolution.  Well, it's actually _double_ that, because I'm using an interleaved step style in the software - it creates kind of intermediate steps.  My stepper motors have 400 steps per rev, so I enter 800.  
• machine.motors.mmPerRev: This is how much cord is extended per revolution.  It is essentially the circumference of the sprockets, though with these beaded cords, it's actually the length of 8 bead sections.

If you are changing these settings, you are best of restarting the app afterwards.  There's a lot of other calculations based on these figures, so a fresh start is safer.