I use them all the time. Run them about 1100 rpm. Some software will compensate for the dia, some won't. Edge finders will get you to within ±.001 or closer when done correctly.
Other methods I've used, (some not safe and I'm advising you NOT to use them), are to position a sharp tipped tool, angle cutter, center drill, or even a scribe held in the spindle, and eye-ball it so it's close. You can get to within ±.015 or better this way.
You can program a non-rotating tool to come down to position the part, using the machine/program to locate with, (aka a tool stop or drop stop).
You can take an end-mill, rotating at about 300 rpm, and hold a strip of paper between the end-mill and the part, and jog up 'til it pulls the paper out of your hand. (I DO NOT reccomend this method, as it involves getting your fingers close to the tool) This method is good for ±.003 or so.
Matt
San Diego, Ca
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(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)