This is from an old post of mine 10 years ago now.......
I think you will find, if you try cutting with different tools, that many things will work for you. Here is an assortment of tools I use for scrimshaw work on horn, bone, and ivory. For many years, I did most of the work with a very large sail maker's needle (second from the right) stoned to very sharp triangular tip (it cuts easily in any direction.) The other tools are used to make bolder or finer lines. Conventional gravers, scribes, and surgical scalpels are all very useful, although some work better in horn than in whale or elephant ivory. Try anything like these that is sharp. You may find one thing that works better for you than another. However, the 4th tool from the right is an aluminum handle with a collet arrangement at the tip to hold 3/32 " diameter dental burs. It is easy to use and easy to replace the scribe end with various tools ....and can be had from jewelry supply houses.
Cutting done with a graver and scalpel on horn:
Cutting done with sail maker's needle on whale ivory: