Brake disks for the Yamaha Roadstar project - Part 2

Finally, the brake disks for the Roadstar are completed. It took me two attempts to do them, since I broke a 0.6 mm drill in and couldn't get it out, so I had to scrap the part and start again. The process of making them was as following:

• Installed some aluminum bar stock on the lathe and turned down few mm, to get to the 25 mm required diameter. The plan was to make both disks at once, so I took into account the desired brake disk's and the cut-off blade's thickness
• After that I removed the chuck from the lathe, with the bar stock still in, and mounted it on the rotary table, on the mill. Careful adjustments have to be made to align the spindle to the center of the brake disk. Then I started drilling the holes. I chose a simple pattern only with holes, in order to make it easier to fabricate. Basically there are five 4 mm radial holes, one 4 mm center hole (for the hub), five 0.5 mm radial holes for the bolts and forty-eight 0.6 mm cooling holes. Drilling the micro holes is tricky as the drills can easily break (which happened once) so I had to take my time. Also to make both disks at once, I had to drill deeper holes (around 2-3 mm), which is not really possible with such small drills (they snap easily). So in the end I had to do the disks separately
• After the holes were drilled, I mounted the chuck back on the lathe and cut a 0.8 mm "slice" from the bar. The 0.1 mm extra is needed for the finishing job, since the cut-off will leave a rough surface
• I then mounted the disk on the Dremel and polished the disk with 180 grit sandpaper, reducing the thickness to 0.7 mm

The disks should attach to the wheel hubs with 0.5 mm micro bolts; I intend to buy some from Scale Hardware.

All in all I am content how they turned out. Some photos below.