> The Hightower I think uses a 5/16 blank as standard,usually with a thin cardboard shim under it. The shimming is important to establish proper center height so they cut properly. This is easily fixed with a QC toolpost.
Carbide can indeed be ground and honed to a level of sharpness rivaling that of HSS,and will stay sharp far longer than HSS,but you will still need HSS for certain things.
Carbide tools can be bought cheaply,and may be effectively reground well,but it won't be as durable as high quality carbide will.
For single-point carbide tipped cutters,I HIGHLY recommend Micro-100 brand. They can be ordered thru Travers or directly. They also have a wide range of toolholders that use various indexable carbide inserts. The one you will use most of the time will be an AR style cutter,used for cutting and facing to a square shoulder.
Keep in mind that whatever carbide you buy,it will more than likely need to be reground dead-sharp for use on wood,leather and the various plastics/phenolics. The factory radius works fine on steel,but will usually "push off" rather than cut when doing cue work. Tommy D.