Had to destroy my AIO due to RMA, but is it possible to use AIO rad for custom loop?

[RedMogg]

As I understand it, only Alphacool & Raijintek use G¼ threaded radiators.
I did something similar to what you're trying to achieve, but I started out with the Alphacool Eisbaer - made life a load easier.

Look about online - there are quite often B-grade deals on the bigger Watercooling bits. I picked up a 240 for £18 delivered.

 

[LePhuronn]

In metric terms. you want a 11.6mm or 11.8mm drill bit for a G1/4 tap. Bear in mind that fittings have a minimum of 4.5mm thread on them so ideally you'd want your radiator end tank's wall to be that thick to properly hold a thread and support a fitting screwed in. I'd say it was unlikely you have this.

But ultimately if it's a DIY project for exploration then go for it. Even though it's aluminium, I'd still suggest a titanium coated drill bit rather than simple HSS so it cuts very cleanly. Don't forget to rinse the rad out afterwards to remove cutting swarf. I'd also suggest deburring the hole too prior to threading so it's a perfect circle. And if you want to be extra tidy, put a 45 degree chamfer on the hole to a maximum diameter of 13mm so the o-ring on the fitting has a nice little groove to squish into (you probably won't need to deburr if you're adding the chamfer).