I tried to level the movement as best I could from front to back…and we ended up with about a .0005” change from front to back. Side to side we had a .01” drop from right to left (mostly due to the .02” shim). But now that I think about it, we could have created that angle in the lathe chuck too. Anyhow, in the mill head we used a 1” dia. aluminum mandrel with a piece of 400 grit Trizact (a 3M product) super-glued to it. All the cutting is done dry – we tried lubricant, but it didn’t work…maybe it would if the lubricant was flowing over the material during the entire cutting process…but we just experimented w/ spraying a bit on our practice brass discs just to see how it worked.
With each pass, you are scratching about a ½” wide surface area of the movement…then, when you move over the 2.5mm and make a second pass, the stripe is created. Does that make sense? This is one thing we found out when we were doing our practice runs. I initially thought since the movement was angled, a perfect 2.5mm strip would be laid down w/ each pass…but that’s not the case…the “stripe” is easily ½” wide, then you simply put an edge one it w/ each pass. And there you go...
A couple of updates to the striping process. You need to make sure that you have as close to perfect of an edge on your mandrel. I'm currently working on a few more pieces and found that as I replaced the Trizact, the edge of the mandrel was getting a bit beat up. Also, I wasn't taking the time to perfectly trim the Trizact to the mandrel. And the result was...well, the result was nothing but crap. Take a look...this is how NOT to stripe a movement.
Once we straightened the edge of the mandrel and took care to match the edge of the Trizact with the mandrel, the stripes turned out perfectly.