Brodbeck Surface Grinder MagSwitch Chuck UpgradeUpgrade for original Brodbeck Ironworks Surface Grinder. It allows owners to change their on only magnetic chucks to on off switchable magnets. It retrofits to the same rails and bearings. This upgrade kit will include the MagSwitch chuck and shim kits (which will include one of each of these shims 0. 020, 0. 015, 0. 0125, 0. 010, 0. 0075, 0. 005, 0. 003, 0. 002) to re dial in your surface grinder. See upgrade video for installing and re tuning your