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.

Brake disks for the Yamaha Roadstar project

I spent most of the past month designing a custom rear view mirror for my real motorcycle. Unfortunately I realized that the parts would be too big for the footprint of my Sherline mill so I put that project aside.

Now I am back to the Yamaha Roadstar project bike I introduced on the last post. Last evening I have started to turn the brake disks. Unlike the real bike, which has two front disks, mine will have only one upfront and one on the rear and it should look like this.

It has 25 mm in diameter (the same as the part in the kit) and 0.5 mm thickness (the kit part has 0.8 mm but looks too thick to me). It will be turned in 6061 aluminum. As you see, the patterns require drilling a lot of holes of various diameters. I am trying to make both disks at the same time and then just cut each one, like a slice of bread :) Might not work though as the tiniest holes are only 0.5 mm and cannot go deep enough (around 2 mm).

Below the stock aluminum bar reduced to 25 mm on the mill. All there is left is to drill the cooling holes, a lot of them...