I've been working with mostly" maple burl" since about 1985. A little difficult but not because of the grain, I found. Just going through blades and being sure to cut so that the finished cut looks the same on the back. One of my problems with the burls is that the points that held the bark intact, are very, very pointed and sharp. The slabs sand to a beautiful finish. I use mostly 1/16" drill bits but have a big supply of very small bits. ie. #58, 60, 65. I do have a problem with bits that don't have a long enough shank to go all the way through the thick slabs. I found some very, very small aircraft bits, as they are called, but they have such a long, vulnerable shank that they break very easily. I've been known to shorten that shank (shush, don't tell the manufacturer) so that it works for me. Thank you so much for all your kind compliments.
Jane