Forstner drill bits are essential for clean surface drilling tasks. The Forstner drill bit has 3 main parts those are point angle, cutting rim, and cutting edge. Each part can be dull during its service life. You have to carefully, sharpen the Forstner drill bit due to its curve surface. When you try to resharpen it, do not sharpen it from the outside. It will affect the hole diameter and bit performance.
When you resharpen the Forstner drill bit, you should pay attention to the below steps.
Forstner Drill Bit Sharpeing Tools
When you need to sharpen a Forstner drill bit, you should use the below tools.
- Round slip stone
- Triangular slip stone
- Mini diamond hone
- Forstner drill bit
- Abrasive grinding cone
Step 01 – Identify the Type of Forstner Drill Bit
Normally, there are 3 main types of Forstner drill bits. Those are
- Sawtooth Forstner drill bit
- Continuous Forstner drill bit
- Wavy Forstner drill bit
You can see there is an extraordinary difference between them. So when you resharpen them, you have to use different tools. You can use these tools for drill bit sharpening.
Step 02 – Inside Bevel Sharpening
You can sharpen inside the rim using a Dremel with an abrasive grinding cone and round slip cone.
Using an Abrasive Grinding Cone
- First, secure the bit in a bench and check the rim surface for unevenness.
- Then touch up a Forstner bit, and try the top edge of the bit’s rim with a file, removing any nicks.
- If the beveled edges of the cutting spurs inside the rim are uneven, grind them using an electric drill fitted with an abrasive grinding cone.
Using a Press Drill
- First tighten the fastener drill bit in a vice
- Then tighten the round slip cone to the press drill
- Match the angle of the rim and rotate it through.
- Sharpen a few strokes inside the rim until you get a proper sharp edge.
Sharpen Saw Teeth Forstner Drill Bits
Sawteeth Forstner bits have teeth. So you should follow these steps when you are sharpening the back of your teeth.
- Use the triangular slip stone for sharpening the saw teeth.
- Lock the bit into a vise and lay the slip stone against the back of each tooth, matching the angle of the tooth flat.
- Do a few strokes on the back of each tooth until it is well-sharpened.
Step 03 – Chip Lifters Sharpening
- Use a single-cut mill file to lightly file the inside faces of the cutters.
- Hold the file flat against one of the cutters—also known as chip lifters—and make a few strokes along the surface (above).
- Repeat with the other cutter. Finish the job by honing the beveled edges inside the rim with a slip stone.
Step 04 – Point Angle Sharpening
- You can use the triangular slip stone again and use your thumb as a guide to keep it off of the chipper that you just sharpened.
- Give it a few strokes to touch up the centering spur.
When you sharpen a Forstner drill bit, you can use light tools such as a file, Dremel, press drill, etc. You must not sharpen the outer surface of the rim because it affects the drill bit hole diameter. Sometimes when the outer surface is damaged, it affects to improve the friction. As a result of this, the bit will be overheated. So you should follow these steps for the best result.
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