I've bent tips on a wood stove. Done it several different ways. 1. Just heat the belly good and hot until it bends by hand or in a form. I have used oil and done it without as I temper. 2. I read on a post some time back, (believe it might have been Toomanyknots) to soak a towel, wrap the limb with it, cover with foil and heat. Tried it and it worked really well. No real trick to either. Thicker wood might require a strap on the belly to keep it from splintering.