Review on Lenox Tools 3084712X 12 Inch Extension by Devin Jenkins

This extension seems to be quite well made (in the US). It comes in two parts: a 7/16" hex shank and a cylindrical chuck. with a 7/16" hex head secured with a shear pin. Socket head screws are used to hold the bit. The chuck diameter is .935", so with some tolerance on the screw heads it can only drive 1". Drill bit (but tight) .A 7/16" hex shaft must match other extensions, or a drill press with a 1/2" or larger chuck is required. This is where I ran into problems. A set of unnamed Chinese-made drill bits worked fine, as does the Greenlee and Bosch bits but the other Bosch bits and the Irwin bits do not.The head on the extension seems to have a couple of points that are right at 7/16" with no gap so just do it a slightly smaller bit. If the gap tolerance is so small that just the difference between Bosch bits and the same product family is not enough, then it says that the gap is too small. Since it is a Sec If it is a square head, you cannot repair it yourself with a drill or grinder. (Although grinding the shafts on any of your drill bits that don't fit is an option. I did that with my Irwin bit.) It looks like Lenox makes this part specifically as an extension for their hole saw and not a custom one Target extension for any 7/16" hex bit, but it would be nice if they machined it with a bit more bit shaft tolerance.