How to Sharpen a Carbide Lathe Tip

Tools for the lathe often have carbide tips to prevent heat damage while cutting hard material such as steel or iron.

Lathe tools come in various shapes and sizes. There are tool blocks with carbide tips that can be sharpened by hand to get the correct angle and shape for the job at hand. Using a simple bench grinder and the correct wheel, you can customize the shape of the tip to assure there is enough relief to prevent any dragging while making cuts on a manual lathe. With a bit of practice and attention to detail, you can grind your own carbide lathe tip.

Instructions

1. Dress the wheel in order to grind the lathe tool tip. Carbide lathe tool tips are very hard and will require the use of a hard wheel that is capable of cutting carbide. Turn the wheel on and carefully press the dressing tool against the wheel's surface. You will see some sparks, but carefully move the tool along the surface of the wheel in order to create a clean surface for grinding the carbide lathe tool.

2. Set the tool rest at seven degrees. This will assure that the rake angle is ground properly, allowing for some relief while cutting. Seven degrees is just enough to make sure that the tip cuts properly and that the heel of the tip, which is on the bottom of the tool, does not drag across the material. This relief eliminates chatter, which can lead to a bad finish.

3. Grind the first side of the tool, which will be on the left side with the point facing away from your body, at a 10-degree angle. This is the first step in creating the cutting angle. Hold the tool at 10 degrees and slowly push into the moving wheel. You will see sparks, but continue to push until you see that the ground area is between 3/16 and 1/4 of an inch. The bottom of the tool will be cut first due to the seven-degree angle of the tool rest.

4. Rotate the tool and grind the other side to create an angle that is less than 90 degrees. Push the tool against the wheel and look for sparks across the whole side you are grinding. This will indicate that you are touching the entire length of that surface. Check the point and make sure it is less than 90 degrees. If it is more, re-grind along the same surface, but turn the tool a touch to the right to decrease the overall angle.

5. Grind the top of the tool. You do not want this surface to be perfectly flat, but higher at the tip, so grind the top at a 15-degree angle, downwards from the tip. Hold the tool with the top facing the wheel and the heel towards the right, inwards at a 15-degree angle on the tool rest. Push it inwards toward the wheel, making sure that the entire top surface that touches the wheel sparks. Stop grinding when the tip is sharp on the top and sides.

References

• Sherline: Grinding Your Own Lathe Tools