Here is the old letter press I got back in working order. Every one needs a hobby .I play with it in my spare thime. I make wooden post cards and print different things on them. They are the same size as a regular postcard and can be sent in the mail.
The flywheel has to be that large because that is what drives the press as well as stops it. Look closley at the lower left corner and you can see a moter that drives the wheel and also at the lower side of the wheel is a foot pedal that pressed against the wheel to stop it.