Try using bone points.  I have made barbed points from the leg bone from cows that the dogs drug back to the house.  DO NOT USE A BONE WITH THE MARROW STILL IN IT !!!  When you cut that sucker open, the smell will gag a maggot!  Use one that has dried out.  Also, I cut  the ends off and then saw it lengthwise with a hack saw.  I then put it in a big pot and boil it for 20 minutes or so.  That way, when I am grinding on it and I inhale some dust, it doesn't have live critters on it.  I use hand tools, work outside, watch the wind, wear a dust mask and still end up with bone dust in my nose.  Bill