Review on 3mirrors ALUMINUM Tungsten Electrode Sharpener Grinder Head - Efficient TIG Welding Tool with Cut-Off Slot, Multi-Angle & Offsets, 4 Copper Screw Holes, 1X CNC Mandrel & 5X 25mm Diamond Wheels by Noah Smith

The brass inserts are just the right size for new electrodes and sharpen quickly. The instructions don't recommend a speed, but the lowest speed on my old Dremel worked fine. The device itself makes a very robust impression and should last a long time. Sharpening used electrodes is a bit more complicated. Even if the tip is not flattened, they seem to expand so much from the heat that they can no longer be inserted into the insert of the desired size. You should increase the size by a size or two and grind the tip to a size that fits the correct insert. Not mentioned in the minimum instructions that come with the device.