I like the shovel you have started (inherited). Shovels are one of my main interest. You just have to do a little math and use common sense when figuring speed. I would start by dragging a pc. of string along a surface and decide how fast you need it to move. Then with a tape measure and a stop watch see how long it takes to move the string-say 1', then do the math-moving at the speed you want see how far it will move in 10 sec., 20sec. and 30 sec. etc. and that will give you an idea of the speed you need. Then measure the circumference of you drums and figure how much rope it takes to do one revolution and convert this to the rpm you need to move the rope. I hope this makes sense b/c it is hard for me to explain this stuff trying to type wit h one finger
. maybe this will give you a way to get started and it should become clear after a bit. If you have questions that's fine-me or someone on hear will try to answer them. I look forward to watching the shovel build progress.