Home made macerator

Francesca Knowles wrote:
Garbage disposals don't "pump"....

I think you would find that underneath the shredder table are vanes that act as vanes in a pump. They are a support for the shredder ring but also act as a quasi pump vane within the drain cavity of the disposal. At least every one I've dismantled has been like that. I would imagine they are built like that to afford evacuation of the drain chamber with enough pressure through the final drain opening.
It's easy to prove this to yourself. Fill the sink with water, making sure the disposal is clean, and observe the time it takes for the sink to empty without the disposal powered. Do the same procedure but with the disposal powered.

The Steampunk builder could have incorporated a clean out with his macerator by attaching a plastic irrigation valve and hose fitting onto the dishwasher inlet. I guess a guy could just rinse the 3" hose and disposer by directing water into the disconnected hose, also.