I've talked in the past of using a 3/8 chuck in impact drivers. Now have a 1/2 chuck that fits on a 1/2 impact driver. This allows me to drill the biggest hole with one hand. This one was bought off ebay for $20. After further research I found a much beefier one http://www.lfausa.com/reichel_3.html BTW, Plumber Rick taught me this trick, gotta give him credit or I'll never hear the end of it.