Industry standard runout for rotors is 0.002" TIR and parallel within 0.0004. Even the cheapest new rotors will be within spec. The quality of the casting is all that differs cheap vs expensive rotors. Finally you should apply a non directional finish or else you'll end up with brake squeal and uneven pad wear. You can do this by taking light cuts (less than 0.002) with a feed rate higher than your insert tip radius. Do one cut feeding in, and one cut feeding out. You'll end up with alternating spiral serrations that criss cross and overlap giving a non directional but uniform finish. Same concept and honing a cylinder.
Awesome I used to do that type of work on my free time. I would go to car shows on weekends and hand out cards for brake work. Cross drill chamfer machine and balance. I did about 100 pairs over 5 yrs of time. Guys loved it. Cheaper than buying new from speed shops. Sometimes I would do the brake work for them. 👍👍❤️❤️👍👍
Mercedes does not recommend resurfacing the rotors they are made out of a soft material as long as they are within tolerance you just put a new set of brake pads on then discard of the rotors when they need to be replaced
I replaced my MBZ disks with mentioned affordable rotors. They too were drilled but had no non directional finish. Gave the car to a friend and they are still going years later. Never noticed any sounds. While there is best practice for rotor turning it is possible to do this on a machine lathe. One can indicate off the finished size to set up for the second. It is never best to remove a part with multiple processes but is often necessary. We do not see that this was not indicated nor do we see that too much material was removed. RU-vid is full of comments based on book learning or “how I learned” but, in the real world of machining, what the customer actually brings you and what they desire often means problem solving and some flexible thinking. Many don’t have the luxury of refusing challenging jobs. We all know what the books and mfgs suggest but we all(those who build, fabricate, machine, etc) make compromises all the time. Your employer’s rules, liability issues aside.
You shouldn’t machine one side true and flip it around and use an unmachined surface as square with the flat side. You’ll end up with a wedge. Machine one side after indicating, then use that machined surface true to the chuck face to do the opposite side. This is why brake shops have lathes with tools that do both sides at the same time. Its too time consuming for the average shop otherwise and prone to mistakes.
