Sone Time ago I was heavily involved with bone carving, I have now moved to other hobbies but some experience remains...
I worked mostly with cow/oxen bones. Its like cutting flat plates from a tube, so not very efficient and wastes a lot of material. I never had to make large plates since I adapted the pendants to the curvature of the bone but from my experience the best bone for getting the largest flat plates from would be the shinbone, either front or back leg. only the front surface (thats the flat one) can be used for plates. this is at last one surface that is fairly flat and wide. All other leg bones are somewhat more curved and round, limiting the size of obtainable flat plates greatly. With shinbones (No, 8, 14) I think 4cm,x0,5cmx15-17cm plates are possible. With all these bones the thickness of material is greates in the center and ther gradually tapering towards the end. . Most massive parts thickness is about 15-16mm you can get ,with 10mm on most bones as an average, then tapering to the ends. Femur bones (No.11 ,hind leg) are the largest and have the most consisten thickness throughout, frontal bone No18 is fairly useless for obtaining plates since its convolutet in everywhich way and thickness tapers fast towards the ends. Once the spongy growth of interior bone material sets in the wall thickness falls quickly. Best to cut those ends off and discard them since its also a pita to get rid of the marrow trapped inside the sprongy material. It will retain some and tha fatty content will seep out into the bone after processing.
I obtained the bones from the local butcher for a small sum. These were fresh from slaughtering and to process them I did the following. first sawing off the ends with a hacksaw, preserving ontly te middle section. Then the marrow was removed using a long screwdriver. Scraping off residual sinew and flesh on the outside, does not have to be 100% clean, small traces will be removed on boiling. Steep them in cold
water overnight. Important step, because it will leach out residual blood, if you boil them straight away blood will congeal and make spotty grey discoloration in some spots. The day after I boil all the bones in a large pot for 1,5-2,5 hours with a half cup of washing machine powder added. This will at the same time both degrease and bleach the bone. any residual sinew or flesh can be easily scraped off during/after the boil. dont overdo on the powder because too much will attack the calcuim part of the bone. But doing it this way I never encountered any difficulties in terms of stability of the bone for carving afterwards.
Here is some pictures :
Most of My pendants are either sold or given as gifts but a few remain, from others I only have the conceptual drawings left. Well, I dont do this stuff anymore but it sure was fun in its days.