Same here, 3 or 4 sets of pads on HD truck rotors no issues.
Preparing used brake rotors for new pads
- Thread starter Chris142
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Same. Never had an issue doing this.
It was common practice to resurface rotors and brake drums years ago. It worked then and should work now. If you don't have the right tools to do it, or don't know how, I can see it being a problem.,,
how much does that cost?
I guess maybe I should go in the back and lean over my machine shop guy's shoulder to tell him how to do it? Or do you think true BITOGers should have a brake lathe at home so they can do it properly? I'm just saying most of the machine shop guys in my town are true salt-of-the-earth fellas who are that perfect combination of not highly paid nor highly trained.
It has always worked for resurfacing rotors to remove minor ridges and the brake material from the previous set of pads, but you can't bend a rotor back to true with a lathe.
A brand new rotor is usually only good for 2 or maybe at the most 3 mm of wear, so that doesn't leave a lot of room to machine out any warp after it's already worn down through a set of pads. That's total thickness, so each side has 1 to 1.5mm of life.
A brilliant analogy. 
I see FB market place advertise for $30 per rotor in my area. A new rotor for my car is about $30.
I won't trust those guys who couldn't even take good photos of their workplace and they couldn't keep their place organized and clean for advertisement. I would take my risk with Amazon's 30 day free return instead (you can always buy 1 more to replace the bad one and return the bad one).
Yesterday I noticed the mammoth rotors on the outlaws new F Sport, I don't think I'll be replacing those any time soon. Toyota has finally begun listening to @edyvw
I was hinting at using an on-car brake lathe.
How would that remove warp any better than an off-car lathe? It seems like the technician needs to check runout and if it can be machined back to true/flat without being brought below the minimum thickness, it could be done on either machine.
I would use a wire brush on a grinder. I also have use a grinder to remove an edge on the rotors where the pads don't hit.
You might also use a caliper to measure the thickness to see how even it is. And then once mounted. a thickness gauge to see how true the rotor is.
Assuming that they are not warped and are above the minimum thickness.
Again, I've had good luck with two different O'Reillys. I think all stores recently got new brake lathes -- or at least they did around here.
I think it's around $30 on the retail side. I agree for car rotors it doesn't pay, but truck rotors can exceed $100 ea to replace.
Most recently my O'Reilly was slow to get it done and did it for free as an apology.
The on-car lathe takes into account the hub assembly and removes the variable of setting up the rotor on the lathe’s arbor.
I feel like I'm beating a dead horse here. How does that make any difference to a warped rotor?
I think you're hung up on the definition of "warped." Excessive lateral runout (warpage??) is what causes disc thickness variation (DTV). DTV is what you feel in the pedal. If you machine the rotors using an on-car brake lathe, the lathe is resurfacing the rotor while installed so any excessive lateral runout is removed.I feel like I'm beating a dead horse here. How does that make any difference to a warped rotor?
When you machine a rotor using a bench lathe, depending on the condition of the lathe, adapters, etc., the finished product may result in a rotor with more lateral runout that you'd expect.
