non-jamming/clogging cesspool mixer

thingiverse

My grandfather has a holiday-house which is not connected to the sewage system. It therefore has a cesspool with a mixer inside that turns once or twice a day for some time at 1000 rpm in both directions. The original mixer came off and sunk to the bottom, so the best option was to print him a new one. It had to: - fit through a hole of 12.5cm (<5 inch), so the maximum diameter is limited - be able to function in two directions, so the design is symmetrical - not clog or jam, so the design has smooth edges - not break, so thick fins - not dissolve , so I printed the final design in Polymaker PC-max (polycarbonate) (perhaps ABS is also a good choice) It has 4 M8 mounting holes at 25 and 30mm from the M10 center hole.