I use an 18" Grizzly Drum Sander to thickness backs and sides. I use 100 grit paper, keep it clean, advance mere micro millimeters for each pass yet still can't avoid burning. Any suggestions? The feed rate has been tested from slowest to fastest, yet it doesn't seem to make a difference. The harder the wood, the more prone it is to burning. Must I accept burning as part of the process (I can scrape it off in the end)?