All the information so far is great! Here is a tip that may help. (Worked great for me). If you have two long drill bits, you can go partway through from either direction you choose, then take the loose bit and stick it in the hole you just drilled (blank end first). Then, drill from the opposite direction. Keep in perfect alignment with the other bit and go slow. When you see the loose bit start to wiggle, you're there. Pull the loose bit out and go just a bit further to finish the hole. You can then clear the channel out with a piece of scrap wire. Done!