Removed all the skin to substructure rivet tails & drilled the heads off the 609PP aft spar doubler bars. These are long -4 rivets and even with the heads snapped off they don't want to come out. Did a pilot hole for the rivet removal tool with a small bit and then after the heads were popped I went back with the same small bit and drilled most of the way through the rivet shaft so the shafts can collapse in on themselves. I then drilled a hole in a hardwood block slightly larger than the rivet tails and used it to back up the structure. Used a pin punch smaller than the hole to knock the tails out. RJ was studying for math, but took a break to hold the backing block for me. Thanks RJ! Only did about a dozen because I bent the el-cheapo pin punch, but will get the rest tomorrow.