Well, i had mixed results with the advice provided in your driver example.
I started by creating two gears, one fat, one skinny, with obvious defects so i could track whether they were spinning full 360.
I wasn’t using bones, so the interface options were a little different, but I attempted a constraints: Transform, and right clicked the Z rotation degree window for constraints. I followed your instructions on pressing N in the graph editor and changed the tab from F Mode to drivers.
I found that modifying the “Expr” or expression tab allowed me to type pi directly, however, the program then interpreted this as degrees and i was left with the same problem when simply typing “R + Z” and moving the mouse to rotate the source object (gear 1 -> gear 2)
Well, i looked at your descriptions again, and you had timeline dependence.
So I added a (frame * pi) / 20 for the effect, and moved the timeline bar, but nothing happened! I suspected the “Minimum/Maximum” rotation was confused, since at frame 0, the rotation is 0, but at frame 17 or whatever, the rotation =/= 0. So I made drivers for both minimum and maximum, all in all, i had 4 drivers on one gear.
Now i moved the timeline, and the gear rotates, Hallelujah! (which Tea Party, btw., does a great rendition of Cohen’s version), but woe is me, Gear #1 isn’t moving at all.
Well, obviously because there’s nothing telling gear 1 to move. This got me thinking, maybe i could uncheck the reference to gear 1 in my transform. Nope. Stopped moving with the timeline, so it was dependent.
Well, then comes the next step. Moving gear 1 with the time line. But how? Here’s that dimensional cat toast in a quantum box paradox:
I tied the rotation of the first gear to the second gear, and it worked. divides by zero exploding head
(remember that the second gear’s rotation is based on the first gear)
So, now that I am my own grandfather, I still gotta ask,
How do I do this without keyframes?