I ride a fairly heavy bike, and realized I never used the largest gear on the front derailleur. I decided to replace it with a smooth plate, which acts a chain guard. I made this at TechShop.
Step 1: Mount the Chain Ring on the Lathe
Since I had access to a metal lathe at TechShop, I decided that was the tool I wanted to use. I used the four jaw chuck on the metal lathe, since this crank set uses four spokes to locate the gears. It is important to center the part when using a four jaw chuck, hence the dial gauge on the left in the photo. Centering is done via small adjustments to each of the jaws, measuring the runout between adjustments. This was by far the longest step in the process.
Make sure the chain ring is held in tightly, but not too tight or the gear will flex out of round.
Step 2: Cut Teeth Off of Chain Ring
Step 3: Replace Old Chain Ring With Toothless One
Remove the old chain ring, and place the toothless one in its place. Replace the bolts and tighten them down, ensuring both center and outer chain ring are seated properly.
All done! Now, go for a test ride, without worrying about shoelaces getting caught in the chain.