batrider said:
There was a good thread on this a while back. Turning the disk with a spiral cut like most automotive disk lathes does not work well according to hobot's research. I believe it. The factory recommended Blanchard grinding but this doesn't seem to be available much anymore. It was pretty common in the '70s.
The disk when brand new is already pretty close to the minimum thickness allowed so may end up too thin after machining. I'd get a new disk.
hobot said:
The prior consensus was the rotor is thick enough to have it resurfaced more than once and no one has found a minimum thickness listed anywhere so good to go for a few more generations. Wonder if pads that are of grinding stones could allow us to DIY perfectly.
As pointed out by both Batrider and Bruce, it is Blanchard grinding, and it leaves a fantastic orbital surface finish that lays contrary to the circular motion of the rotor. 'Much preferred over lathe turning! Picture holding an orbital sander to the side of the disc as the wheel is slowly rotated.
Based on my own (limited) experiences, the rotor has plenty of meat, unless the PO already cut it a couple of times before. Check out
grabbing-front-disc-brake-t19272.html for more insight. If you see splotchy rusty/no rusty zones on either side of the disc, you're still running on the original chrome (like I was). 'Plays hell with trying to get good braking action!
btw, there's a local in Boise that still can do this, and he charged the paltry sum of $50 last Spring. He starts by anchoring the disc as if it was bolted to the hub, turning the outer face, flips the disc over, and finally grinds the back. The idea is the hub face sets the stage for the subsequent cuts. 'Worked great on mine! I'll try contacting him today/tomorrow for shipping details and the like.
Steve, a couple of concerns with using the caliper as the refinish source (besides the grit created); no way to control disc waviness, and the finish lay is back to being concentric, just like the lathe. Bad!
Nathan
