Many years ago I worked in a factory making agriculture machinery. In the machine shop there was four big radial drills. The biggest hole we used to bore was 2 1/4 inch. I guess the speed was about 45 rpm. We used a constant flow of accolade oil and water for cooling, when mixed this was like thin milk. Our big drills would put a lot of pressure on the bit, but the secret was to keep a continuous strand of swarf coming off if you could, then you know you had the settings about right. I used to sharpen in the factory simply holding the drill to a fine grind stone. It comes with practice, getting the angle right and getting a cutting leading edge to the drill. You stated you use a 3/8 pilot hole to drill a one inch hole. I think this size hole is a bit too big. Try a pilot drill about the same size as the chisel lead of the drill bit. Plenty of pressure, cool with something will help and lubricate. Things have moved on and we sometimes started to punch holes. Circular cutters have improved. To keep an edge on my bits today, I use a cheapo diamond file, again it takes a little practice but I only use normal quality drills for every day cutting although there is some specials in the cupboard should I get a hard piece of work.