@fromwastetowind I think this is an 'inverse' Polar printer, and it is irrelevant to the firmware if it is the crane that rotates or the bed. The nozzle just needs to travel along a line drawn between the centre and the circumference, ie along a radius line.

See https://docs.duet3d.com/User_manual/Machine_configuration/Configuration_Polar

Apart from the links already mentioned, there was a similar printer design (though running on a hacked version of Klipper) at SMRRF: https://www.youtube.com/live/Hlw3mt-x0nE?si=amwlz8DMR0daYQjS&t=1437

You should be able to put a print anywhere on the bed, just not in the centre. M669 Raaa:bbb defines the minimum and maximum radius in mm.

Ian