hole grinder machine
4 Best Glass Grinders - July 2021 - BestReviews. Pros. This entry level glass grinder runs at an impressive 3000 rpm. It has a compact 7-by-7-inch work space that is designed for smaller projects and has a standard 5/16-inch shaft that will accept all standard grinding bits. Cons. Because it is for beginners, this glass grinder is limited in scope.