I have a half inch square carbide tool that I am making a handle for. I know I can rout or cut on a table saw two halves of the handle and then glue them together and turn. I would like to use a whole piece but I don't have a 5/8ths bit that will go the 7 inches deep that I need. I was planning on using a forstner bit and I have an extension but it's diameter is more than 5/8 th of an inch. What are my options to get the job done?