The Home Machinist!

I was just wondering.....does anyone here trun their own Car's brake rotors on their lathe? It seems to be a basic job. What would the roadblocks be?

I've used a brake lathe every now and then for 40 years. Still have an Ammco rotor lathe that I keep around for the occasional rotor. I know better than to try it on my regular lathe. Several reasons for that.

You need to remove the same amount from each side to keep the caliper centered. This isn't critical, but has to be kept in mind.
Single point cutting from one side can push the disk enough to cut with a warp. This happens when using a brake lathe with only one cutter in play, even on large, heavy rotors. I've done it, learned my lesson.
Brake lathes use arbors and adapters to center on the bearing cups. You'd have to make them.
Ammco lathes use negative rake cutters, which require a lot of pressure but give a smoother cut.
FMC and similar may use positive rake.

Having said all that, it can be done if you are careful and think about your setup.
If you have a 14" or larger lathe it should be rigid enough. You would need to build an arbor and adapters, and probably turn between centers.

All things considered, you'd be better off paying the $20 to have it done, or get friendly with the guys at the auto parts store so they will show you how to use their machine, and let you use it. I've had similar arrangements with good customers back when I had stores.

I have done a few, really stretched the capacity of a 13" lathe, particularly to get to the backside, headstock, side of the rotor. I did make a mandrel, 1" dia, with cones to support and center the rotor or drum. Most times it came out fine the first time but I remember redoing one. I have also done the faces for the electric brake pucks on the travel trailer, did that with a rotary table and a cup wheel on the vertical mill.

You can do it, given a suitable lathe and time to make the setups.

Thanks for the info. Rex, you explained it well, I never considered 1/2 of what you said! I guess I'll keep taking my rotors to the parts store and pay the $18, and use my time for more "fun" work.....like guns!

Better yet, offer to go some gun work for the guy who owns the parts store then get them done for free.

When my rotors need turning, I buy a new pair and save the old ones. Then I get them turned at my convenience. Next time, I just swap them out and the ones on the car go on the shelf.

Steve

I'm in DFW, have rotor lathe, and need some simple gunsmithing done.

BTW, I should add that there is a newer style of rotor on small cars and even some light trucks. It's called a composite rotor, because it has a stamped steel center bonded to a cast iron friction plate. They are evil SOBs to turn unless you have an expensive adapter set. They are made to be replaced, not machined. The good news is they are cheap, typically under $20 each. It's easy to spot them. The edge of the "hat" is rounded, not squared off.

The responses are so good there is little to say, just a recount. Toyo rotor I fussed with, centering, all that. Cutting through the hard spots and configuring all ways of positioning the X and compound. When done it was still above rejection thickness but like was said earlier, I didn't have the opposing tool or the room to use one.That requires a lot of realigning for the other side.
No big deal except the next day i was at the parts place and they had a new one -in-the-box for $20. so that's the last one i tried.

That pretty much sums it up!