Remodel standard power supply unit into a fanless one.

    The procedure of obtaining a straight canal with smooth walls is as follows:
    1. Make the first passage with a 3-3.5 mm drill. Press the drill carefully and keep vigilant watch on the drill in order it wouldn’t off-center: small deviation from vertical doesn’t play role, but if you are not attentive enough it may come out somewhere between the fins :) Alas, this may happen even if you work on a drilling machine. To the point, here the cuts on one of the radiators backfired on me: I had to spot the first centimeter of drilling with a short drill since the long one aimed all the time to bend and slide down into this opening.
    2. Substitute the drill for the 4.5 mm one and make second entry – now it doesn’t mean how you work.
Put 5 mm drill and take off one more layer of aluminium using lubricant (kerosene or engine oil). Drill feed must be interrupted: deepen to half a centimeter, take out the drill, clean the shavings, deepen to half a centimeter more, and so on.
    Finally, the last passage is made with 5.1 mm drill, also using lubricant and in interrupted mode (I bindingly claim that a 5 mm pipe doesn’t fit into the 5 mm canal :)). You may get an idea to save your time and cut the canal through immediately with the last drill; I recommend you not to do this. We need walls as much smooth as possible, and this means that shavings shouldn’t overfill the offtake channels of the drill during the process of drilling (if this happens, the shavings are forced out to the canal and we get pretty furrows on its walls). As a matter of fact this is the reason of gradual drilling and interrupted drill feed: to minimize the amount of shavings.
    Disjoint the radiators and get such result:
 

    The first canal from the middle of radiator illustrates my warning concerning the possible run of the drill. If you also get a slight skew don’t be upset, just bend the appropriate pipe. You can estimate the consequences of more considerable skew :). The last detail: if you look attentively at the edges of the “halves” of the canals, you may notice barely noticeable rough edges – it’s better to get rid of them. The easiest way to do this is to remove them with a sharp knife; you must be careful: the edges themselves are as sharp as a razor!
    If you don’t want to drill you may act in a simpler way: squeeze the pipes between radiator like in a sandwich; it looks as in the picture: