Review on Spiral Combination M3 M10 Automatic Spring by Paul Lewis

The concept is good, but there are problems with the implementation. First, you have about 1/2 inch or less depth between the drill bit and the tap. So if your material is thicker you will have trouble grabbing a portion of the tap and starting the thread before the hole is all the way through and the tap cannot be used at a reasonable RPM for drilling, not to mention that too the swarf from the drill has nowhere to go until the chisel breaks through. When you are drilling and the tap starts cutting, the drill will definitely immediately experience a large torsional load. I'll drill holes in composites and wood, I'll do for that.