Brian, the green silicon carbide stone do a better job cutting steel weather its soft or hard. The stones last and hold their shape a lot longer. The Aluminum oxide stones do best with the soft metals like brass and aluminum. When I started out working on clocks I purchased the lathe you are using. And I hate to be the grench here but I quickly discovered its lack of repeatable accuracy and few choices of attachments were a henderence to its use for clock work. After about a year I sold it and went with the Sherline. The collet holder you are making looks like it will substantially reduce the between the centers working distance and limit the work you are able to do on the lathe. RJ, I've had the chance to work with the Harbor Freight bench top lathe and if I were you don't bother. It's Chineese made and is considered a work in progress. That means you will have to do a lot work on the lathe itself just to get to a decent accuracy and sometimes you can't even do that. You will also not have very many attachments you will need for clock work. For what they cost your better off putting your money on something else even if its used.