A bone handle on a knife makes it aesthetically pleasing. Bone works best as a stacked handle. Stacked handles are a little more difficult to make than other handles, but they add value and visual appeal, an important point if you are making knives for sale.
Use a fine mill file to adjust the fit of the bolster or guard to your knife. The bolster should be snug against the blade. Lay the bolster on your leather pieces. Use black marker to outline the slot for your knife tang on the leather, as in the diagram. This will make two leather washers. Put the bolster and the first leather washer back onto the knife tang.
Lay out a length of bone for your handle and cut the ends with your hacksaw. Use a chainsaw file to expand the hole inside the bone, if needed, to give a snug fit. Place the bone and the second leather washer on the knife tang. In order, the piece indicated in orange is the bolster, which is another name for the hand guard. The two brown pieces are the leather washers, and the pink section is the bone handle. At this point, the screw-threaded tip of the knife tang will still be visible.
Screw the butt cap, which is another name for pommel, onto the knife tang. Test to make sure that all pieces align properly. Remove the butt cap and put a drop or two of thread-lock adhesive on the threads. Screw the butt cap back onto the tang by hand as tight as possible. Allow to cure overnight.
Use coarse and fine files to shape the handle, and then hand sand the entire assembly from 80-grit through 440-grit emery paper.
Use jeweler's rouge on a polishing cloth to buff the handle to a mirror finish.
Always wear wraparound eye protection when cutting, sanding or grinding bone or metal.