240 RPM is fine for drilling with 1/2" bits into mild steel, aluminum, or stainless. No problem.
The problem is when you want to use bigger bits, or hole saws. I used to use a small benchtop craftsman which I set for it's slowest speed - 600 RPM - and no problem with 1/2" and smaller bits. Once I started using hole saws, that drill press just was very unhappy, and often the saws would get hot enough to temper and the teeth would disappear in a flash. Hand filing a hole saw is a lot of work, but I've done it because i'm cheap.
Last summer I bought a floor standing Delta "X" type drill press for about $950 or so. It's variable speed with levers rather than moving belts around, and it goes down to 150 RPM. I can use a 6" diameter hole saw and bore right through mild steel no problem with the beast. Now that I've fabricated up a small cutting fluid pump thing, and a flexible outlet hose to direct the flow onto the hole saw, I find that the hole saws last a really long time. Instead of two or three holes as before, I can get 30-35 holes using "Ace Hardware" generic hole saws. They are cheap and made by blue mol, a respectable brand.
And I don't use cutting fluid, I use ATF transmission fluid, simply because I have gallons of it sitting around and nothing to pour it into.
