Drilling a bung

Northern Brewer General
1

I have some spare bungs around, and want to drill one for an additional blow off tube. I know the hole needs to be 9/16" for my tubing, but since the bung is rubber I know it won’t drill smoothly.

I have a drill press to keep it vertical - any suggestions on how to get the inside of the bung smooth when drilling it so it’s easier to sanitize and keep clean?

Thanks

2

I have heard of folks doing that by 1. freezing the bung, and 2. making the “drill bit” out of whatever O.D. metal tubing that matches your vinyl tubing. Sharpen the metal on the inside so the edge is at the outer rim.

3

Thanks - freezing it makes sense. I’ll give it a whirl.