I suspect that by the time you have assembled the bits into a working machine, you will have spent more time (and money?) than you will recover from the mechanical improvements. Also, if you are working alone it will be tedious to feed apples into the machine and clear the pulp. Standing and turning a handle, this is easy.
Of course, if you have two people it would be faster.
As an aside, I have used a weed shredder to chop apples. This one is powered by my lawn tractor but one of the electric ones should work the same. I rinse it out to remove any obvious nasties before starting and then again after. It doesn't seem to mind.