Although carbide is a very resilient metal, you may need to sharpen it from time to time. To properly sharpen a carbide lathe tool, you must carefully follow the angles already ground. By simply resharpening the angles that already exist, you can save yourself the money you would have spent buying a new lathe tool. With a little practice and care, you can sharpen dull carbide lathe tools in just a few minutes.
Dress the grinding wheel to successfully sharpen a carbide lathe bit. Place the dressing wheel against the moving wheel and press down to remove the outer layer of used grinding wheel material. This will give you a strong, new surface to sharpen carbide.
Set the tool rest at seven degrees, which will give you the correct angle to follow the existing formed edge.
Grind the side following the angle of the tool. Make sure you see sparks across the whole side edge, indicating that the wheel is sharpening the side. Lay the tool flat on the tool rest, bring the angle in flat against the wheel and apply light pressure to sharpen the edge.
Grind the front edge in the same manner as the side edge. Bring it in straight and press against the wheel until sparks are present along the entire edge, indicating that the edge is being ground evenly.
Flip the tool on its side to grind the top edge. Line the stepped area up with the grinding wheel and press the flat topped area against the wheel until you see sparks. Be careful to grind across the entire top surface at the same time for a perfectly flat area.
Break the front edge by placing the point where the side and front meet. After sharpening, that tip will be too sharp and may cause chatter, so grinding about 0.25 mm (1/100 inch) off the tip will allow the lathe tool to cut properly and smoothly. Press lightly against the wheel until you see some sparking. Check the tool tip every five seconds or so to make sure you don't take too much of the tip off, or you will have to start again.
Always wear eye protection when working with a grinder.