Sorry I don't have pictures of the process, but when you use the step-conical drill bit it has the size stamped at each step/notch on the bit. Take your time and make it just big enough to fit the sample port valve fitting. Drill a small pilot hole and follow up with the step-conical for a...
Thanks!
I used an "Easy Seal Stainless Steel Weldless Bulkhead" for the sample port and a Steel Step Conical Drill bit to core the hole.
You're right a blow off tube is better as this airlock can fill up at times.
I thought it might be helpful for owners of the Catalyst fermentation system to see a thermowell and sample port mod (no leaks) in a photo. Albeit, some may prefer different spigots, you get the idea.
You can also see the new cover with handles.