Can I Sharpen a Cobalt Drill Bit?

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You can sharpen a cobalt drill bit when it is blunt and dull. When you see smaller chipping and lower feeding rate with high heat generation, it is time to sharpen the cobalt drill bit. You can easily sharpen a cobalt drill bit when it is not coated by any material. If you sharpen a coated cobalt drill bit, its coating will be removed, and its characteristics will be reduced.

You can use a bench grinder to sharpen the cobalt drill bit easily. As well as you can use file, vise, angle grinder, stone, and drill bit angle gauge as the sharpening tools. Cobalt drill bit angles should be maintained according to the hardness of the drilling materials. For the harder materials, the drill bit angle should be 135°, and for the soft material, it should be 118°.

You can sharpen the coated cobalt drill bit. Although its coating is removed it will not affect too much affect to the drill bit performance because the outer coating remains on the drill bit. Cobalt drill bits can be broken when the drill bit is overheating during the drilling. Drill bit heat can be increased due to using higher RPM, thrust, drilling hard material, and lack of cutting oil. You can use a cobalt drill bit 1,000 to 2,000 holes successfully. When you observe difficulty to resharpen, broken from the shank end, and there is no sufficient flute length on the drill bit you should replace it.

What is the Cobalt Drill Bit Sharpening Angle?

The sharpening angle of the cobalt drill bit depends on the drilling material; You can drill wood, metal, plastic, PVC, and many more materials using a cobalt drill bit. For the hard material, the drill bit angle should be 135°, and for the soft material, it should be 118°.

When Should You Sharpen A Cobalt Drill Bit?

You should know about cobalt drill bit sharpening time by observing the below behaviors from the drill bit and drilling process.  Those are,

  • When the drilling process becomes slow.
  • When your drill bits do not make clean, perfect holes anymore, understand that they are dull and require sharpening.
  • When you notice that you have to apply a lot of pressure and force to get the work done than before.

Please ensure that you always sharpen your drill bits when they get dull. If you keep drilling with a blunt drill bit, it will harm the drill bit and the workpiece.

What Tools Can be Used for Cobalt Drill Bit Sharpening?

You can use a hand grinder, file, bench grinder or oil stone as a sharpening tool for the cobalt drill bit. When you sharpen manually, you must have a good user experience because cutting edges should be sharpened well and symmetrically.

If manual sharpening is difficult, you can use a drill bit sharpening gadget. Drill Doctor is one of the drill bit sharpeners and it is available for 3/32″ to 1/2″ twist drill bits. But it can’t use for the left-hand drill bits.

How to Sharpen A Cobalt Drill Bit?

You should follow the below 7 steps to sharpen the cobalt drill bit.

  1. Wear a pair of safety glasses to protect your eyes. Do not wear gloves.
  2. Turn on the bench grinder and set a low speed.
  3. Using your fingers, hold the drill bit from the smooth end at a 60-degree angle.
  4. Fasten your hold on the drill bit and bring it towards the grinder. 
  5. Let the bit gently contact the grinder with the sloped side of the conical top and start sharpening.
  6. Take back the bit from the grinding wheel once you finish with one side. 
  7. Repeat this process by sharpening all the sides of the conical top.

Finally, check whether the edges are well-sharpened. You can touch the edges of the drill bit mildly to ensure that it is adequately sharpened. 

cobalt drill bit on bench grinder
Bench Grinder can be used for cobalt drill bit sharpening

Why Does A Cobalt Drill Bit Break While Drilling?

Cobalt drill bits can be broken while drilling when it is overheating. When the cobalt drill bit is used to drill it can be heated due to friction between the drill bit and the material. As a result of this drill bit can be heated too much and break while rotating.

You can avoid cobalt drill bit braking using cutting oil, using lower RPM, using lower thrust, and using a coated cobalt drill bit. As well as, cobalt drill bits can break if they fall on the ground because they are too brittle.

Can I Resharpen A Coated Cobalt Drill Bit?

Yes, you can sharpen the coated cobalt drill bit. Cobalt drill bits are coated with the TiN, TiAlN, and TiCN. When you resharpen the cobalt drill bit these coatings will be removed. Then the performance will be reduced. But it will not affect too much because cobalt always has better strength properties as well as outer coating is not removed during the sharpening process.

When Should You Replace The Cobalt Drill Bit?

You should replace the cobalt drill bit with a new one after it used for 1,000 to 2,000 holes; difficult to resharpen, broken from the shank end, and there is no sufficient flute length on the drill bit.

Are Cobalt Drill Bits Durable Than Titanium Drill Bits?

Approximately cobalt drill bits can drill through 1,000 – 2,000 holes in materials like cast iron, bronze, brass, stainless steel, and alloy steel. They are highly resilient at higher speeds and withstand higher temperatures than the titanium drill bits. The coating of titanium drill bits wears off, gradually changing mechanical and chemical compositions under high temperatures. 

Such things will not occur when you use cobalt drill bits, which are more durable than titanium drill bits. Cobalt drill bits are a mixture and, therefore, do not change composition as they are being used. For this reason, Cobalt drill bits are more durable than titanium drill bits. 


Tom Mackency

Tom Mackency

Hi, I am Tom Mackency. It has been 10 years that I have been working as a professional woodworker since 2013. I am really enjoying my carrier by creating many kinds of projects in my workshop. But mostly I like for home improvement projects. Home improvement and DIY projects are the most interesting things for me. More than that, the coolest things are power tools. Those are very precious and efficient than a decade ago. So I try to introduce so many things about power tools, woodworking, DIY projects, home improvement and many more interesting topics here.


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