Hi Herbie, I have a knurling tool that works by cutting the knurl, although it's generally too dear to purchase for the home handyman, I retained mine when I retired. Although I haven't used the scissor type, they look like they would be the best choice as they have opposed pressure on the wheels. On a conventional knurling tool, a great lot of pressure is required against the material and so putting a lot of pressure on the bearings in the headstock and on the infeed screw.
Paul.