Fwiw, I tried the harbor freight grinder and returned it. It had waaay too much play to get consistent cuts. Junk. For the money you will lose much more in chain loss than what you save over buying a better grinder. The northern tool grinder, or better, an oregon grinder will be much easier to use and make more consistent grinds on the cutters. Still, chain grinders are for fixing worn or rocked chains, not for regular maintenance.
Trying to save you time and $$$.....