Ok this may be a dumb question. I have been turning slimlines and they use the 7 mm tubes..so I have a 7 mm mandrel. Now...if I want to get into other types of pens with 8 mm...10 mm ect tubes..does that require me to obtain the matching mandrel? I saw online somewhere if you have the 7 mm mandrel its good for all sizes. Just matters that you use the correct bushings for pen your turning.