Framebuilders - disc brake mounts

i'm making a cross-bike for a friend who wants disc brakes. how well do the disc brake mounts have to be aligned? do the disc brakes themselves have any way to compensate for a slightly misaligned mount? is there an easy way to do it with a home-made jig?

I'm just familliar with the avid cable disc brakes, they are alignable, within reason, in the brake itself. The mounts are not accurately mounted on a lot of production bikes.

You can make a home made jig to hold it. The basic method is you mount the hub and disc to the fork, then you clamp the brake on the disc, and with the brake attached to the bracket, the only missing link is welding it to the frame. Tack it and then weld it in place after separating all the brake parts.

sounds good, thanks. i also found some rear dropouts that have disc brake mounts already attached. one less thing to worry about.

A friend of mine made a mtb frame and he had a lot of trouble with the tab alignment. I think he had to re-do it a couple of times. On the second one he used the dropouts you mentioned and he said it was a LOT easier.