I use a single speed Dremel model 275 with a Dremel tabletop speed controller. The table top speed controller allows you to really fine tune the speed. I also use the Dremel brand keyless chuck (I had one of the cheaper knock offs and it was way out of balance). I also use a foot switch that is only on or off. With the foot switch, you can set the speed a bit higher and just take your foot off the pedal if it goes a little to fast. I have not removed the Dremel keyless chuck since I bought it over a year ago. Trust me, this is the BEST way to use the Dremel tool and it only took me 20 years to come to that conclusion. I constantly use #80 drills and been using the same for well over 4 years. Have drilled probably over 1000 holes with it in brass, wood and plastic.