Use sharp bits when drilling and put tape on the oppisite side to help with chip out.Sharp belts to keep from burning the bone,I like useing cheap A/O belts and new one on each handle.Also most dyed bone will come looking black with extra dye,clean well with acetone and a toothbrush before useing.
Do all the thinning from the back side. and just final shaping and sanding on the front.
Stan