Drilling a plastic corney lid

One of the corney kegs I acquired came with a green plastic lid, instead of the more common SS lid system. While it does seal just fine, I don't like the rubber 'pressure plug' and much prefer to have real control over the pressure in the keg as I do with the pressure release on a SS lid.

So I was thinking about drilling the lid so that I could use a corney keg as a fermenter.

The thing is I know nothing about drilling into plastics. I only really get one shot at this-- if I crack the plastic it's over.

One advantage is the 'rubber pressure plug' in the lid will be a perfect guide for the hole saw. It fits into a hold right down the center of the lid.

So the question is: how do I drill in plastic?


And a secondary question is: any opinions on what size hole to use?

If the pressure plug acts as a one-way valve, you really don't need to do anything else, it's an airlock. But, drill slowly and size it to match an airlock gasket. You could cut it for a cork, but the gasket will give you a better seal if the hole is less than perfect.

Yeah-- the pressure plug does work as a one way valve but only after the pressure gets really high (~90 psi-- I ran it up cause I was curious) and there's no practical way to 'activate' the pressure release.

Good point on the gasket.