Templates
You're going to need some templates. There are a number of things about concentric balls that require to be, well, perfect. Or nearly so. Here are some examples:
- Making a chuck to hold a sphere
- Making your own balls
- Checking if a purchased ball is anywhere near round
- Getting your cutter shaped to cut a correct chase
- Setting the depth of your cutters
- Setting the depth of cut for your drill bits
There are a few general types of templates you'll need:
| 2-1/2" circle | image |
| Template with a 2-1/2" circle cut out of it | image |
| 1/8" alternating color concentrig circles | image |
You can make templates with a decent quality compass and some card stock. I recommend getting a 2-1/2" craft punch that will make perfect circles every time. As for the concentric circle template, I used Visio to make one that I use frequently. You can download below.