What are the benefits from the variable speed grinder, as opposed to the standard grinder?
The variable speed gives you options of more control or more efficient grinding depending on the work you are doing. Diamonds like to go fast, so the faster they go, the faster they grind the glass, but you also lose control over the grind the faster it goes. With a single speed it balances grinding efficiency and control in a mid-range speed. With a variable speed, you can grind faster for large, easy to control surfaces, or slow down the disks for more precise control on smaller surfaces like facets.