Those Holes I Mentioned

Right. Holes. Marvellous things they are: You can’t fill them up or they’ll disappear. You can’t store anything in them because stuff just falls through. Ahh but they are good for one thing… passing stuff through, of course!

50mm fans aren’t small strapped onto the sides of the UPS I have, but they are very cheap, considering they were mass produced by the millions to cool Pentium class CPUs. So a 50mm hole isn’t unreasonable to ask, is it?

The UPS is about 150mm high so there must be room there somewhere! In fact, just ahead of a bulky power transformer inside the UPS sit the power rectifiers and transistors that need to be kept cool when the UPS is running on battery power. There is just about enough room for a perfect 50mm hole on one side, and on the other, there is lots of room for another.

On the left side (as viewed from the front), toward the rear of the UPS there is a diagonal brace made of aluminum that provides structural integrity for the chassis to keep things square and true under the weight of the power transformer and battery. This causes a bit of an obstruction in airflow from the left side fan’s point of view, but only a millimetre or two, so really it’s nothing to worry about. On the other side, the fan was mounted more toward the front of the chassis to provide a kind of diagonal airflow pattern across the innards of the UPS. This cools all of the components very well, but a straight through pattern would have left out at least two important power transistors—an aesthetically pleasing approach but somewhat self-defeating.

The holes themselves are perfectly round. Let me assure you this won’t happen with a large drill bit. A hole saw will get you close. A hole punch, on the other hand, will not only leave you with a perfectly round hole, but a burrless, smooth hole with no residual damage to the surrounding paint job. And for the creation of such a hole, none other than a Greenlee metal knockout punch 1 3/4 inches in diameter. Okay, so that’s not quite 50mm, but it’s very close.

I’m looking into getting some photos developed shortly to illustrate the intricacies of all this hole making. I know, I know’you—re as excited to see them as I! Alas, we both shall have to wait.