Spent 6 years driving screws with the impact on full speed and a buddy in Tulsa finally asked me why
So I was framing a garage addition over in Broken Arrow last weekend and my buddy Dave was helping me hang headers. I grabbed my impact driver, dropped the speed all the way up, and started sinking 3 inch screws into the doubled 2x10 like I always do. Dave just stands there watching me for a second and goes, you know that's why your bits keep stripping out, right? I had no clue what he meant so he takes my gun, clicks it down to speed one, and drives the next six screws home smooth as butter without a single cam-out. Turns out I've been running wide open for six years because I thought faster meant better, and I've probably burned through $200 in stripped bits and chewed up screw heads since then. The slow speed gives you more torque control and the bit actually stays seated in the head instead of bouncing around. I felt like a total rookie standing in that half-framed garage. Anybody else run their driver on low speed for structural stuff or do you just feather the trigger?
The "more torque control" part is what gets people, because low speed does not actually give you more torque, it gives you less speed at the same torque so the bit has time to seat before the load hits. That matters way more with 3 inch screws into doubled 2x10s than people realize, since the cam-out usually happens in the first half turn. Six years is nothing though, I know guys who ran wide open for decades and just blamed the screws.