This leads me to Today's topic .. When to make a shop jig/gauge/tool? For me, the answer is simple. When I need to achieve the same goal more than twice, it's worth my time to make the jig.
Step 1: Some Options
The quick solution is to drill a hole in a board, which is smaller than the sphere. then put the sphere in the hole and drill away. As long as you didn't move the afore mentioned board, you should be good to go. This is what I did with the Helmet stands ... then who knows what happened to that board. Probably a sacrificial board for the drill press or tablesaw ... then onto the firepit.
It's time to make a jig/gauge/thingy.