How may pad sets will a rotor stand?

We'll just leave it as "you're misguided", then ;o)

Thickness has nothing to do with judder. See snipped text for the reason.. and an example.

An "average" machine shop is, I submit, unlikely to meet the required tolerance. My guess is that you must be going somewhere that can - as I said, just a small variation on either side of any disc will cause judder.

Before I start, let me just say that I usually replace the rotors each time I replace the pads. It's easier, gives me peace of mind, they look pretty, etc.... 8-)

As far as cutting a rotor on a lathe is concerned, it really doesn't impact the overall ability of the part to dissipate heat by a meaningful amount as long as it is still within spec. Consider that a normal "turning" results in only a few thousandths of an inch of material being removed from each side of the rotor. Visit your local machine shop and see how much powdered metal is shaved off a rotor being cut. I suspect that if you weighed the rotor before and after the difference would be insignificant. So you're really not changing the ability of the rotor to act as a heat sink if you're not taking away a meaningful amount of mass and other factors remain constant.

But like I said, I always just put new ones on my car. It's easier.

Cheers,