Quote Originally Posted by polyglot View Post
You really want an f/stop timer if at all possible. There are several to choose from including free (if you can solder) - see my signature.

Failing that, an electronic timer, not an inconsistent mechanical knob.

Failing that, a loudly ticking clock. I printed for my first year with a loud clock and a table on the wall listing 1/4 stop timing increments. I would take the ticking clock over a gralab any day.
I've used RH Designs timers and they are great. I've also built my own using Polyglot's instructions. I do not want to go back to a plain timer. If I had to I would get a digital that I could use with a table of fstop times. Having the ability to program steps in is also very nice for complicated prints.