Spade Bit vs. Forstner Bit – Which to Choose

FACTS CHECKED BY  NICOLE PAV 

Drilling precise holes in wood is an art form unto itself. It is especially true when trying to create flat-bottomed holes. That is where spade bits vs. Forstner bits come in. Both excel at cutting larger holes and flat-bottomed holes in wood. The question is which to use when.

Bosch Daredevil Spade Bit
Bosch Daredevil Spade Bit

This article will cover all the comparisons between Forstner bits and spade bits.

Definitions

Spade Bit Drilling Into Wood

Spade Bit

Spade bits, often called paddle bits, look much like a spade you would use to dig a hole. They have two verticle blades with a narrower sharp point projecting from the center. These drill bits are excellent for drilling flat-bottomed holes with a handheld drill, but they often leave rough spots.

In addition, you can use them to drill entirely through stock, but we advise you to shoot from each side.

Forstner Bit

Invented by Benjamin Forstner in 1874, most people use Forstner bits in conjunction with a drill press or lathe. Occasionally though, you will see them attached to electric hand drills.

They have a center spur that may or may not be threaded. Surrounding this center are helical flutes that shave and cut very clean holes. These blades make them ideal for creating neat and uniform flat-bottomed holes.

Pros and Cons of Spade Bit vs. Forstner Bit

Close Up of a Forstner Bit

Close Up of a Forstner Bit

Spade Bits

Pros

  • Firstly, they cut very fast.
  • Secondly, you can use spade bits to drill through holes and partial holes.
  • But, this type of drill bit runs more relaxed than most and rarely overheats.
  • Besides, you can resharpen the cutting edge, extending the life of the drill bit.
  • Spade bits with corded or cordless bits are also available.
  • Finally, you can use them to make angled holes.

Cons

  • Mainly, spade bits tend to leave rough, splintery holes.
  • Unfortunately, it isn’t easy to create consistent holes.
  • Further, the bit tends to run out of line when drilling a deep hole.
  • Moreover, spade bits tend to wobble a lot when during drilling.

Forstner bits

Pros

  • Forstner bits cut exact holes.
  • Furthermore, Forstner bits cut smooth holes.
  • You can overlap an adjacent hole without loss of hole quality.

Cons

  • Forstner bits tend to cut slower than auger bits or other options.
  • You have to be careful not to apply too much pressure, or the bit will overheat and break.
  • Additionally, they require too much power to use with cordless drills.
  • Also, they may tend to grab softer materials.
  • Forstner bits with larger diameters are heavy and require large equipment to drive them.

Spade Bit vs. Forstner Bit What’s the Difference

Spade Bit, Forstner Bit, and Twist Bit

Spade Bit, Forstner Bit, and Twist Bit

Type of Cut

Spade Bit: Spade bits cut quickly and are best for cutting multiple or deeper holes in a hurry. However, The spots will not be well finished or very precise. Unfortunately, if the quality of the hole is a concern, you should look at other options.

Forstner Bits: If you are drilling in wood and prefer wood chips to sawdust, a Forstner bit will be your best friend. They drill very accurate holes, very slowly. Remember, though, that their woodworking applications are best limited to creating well-finished holes that don’t fully penetrate the wood.

Cleanliness of Cut

Spade Drill Bit: A spade bit will not create the cleanest holes. Most often used in a handheld drill, they tend to wobble and leave annular recesses. In all honesty, these will have edges similar to those with conventional twist drill bits.

Forstner Drill Bit: Forstner drill bits will create a perfectly circular hole with smooth edges and inside surfaces. Besides, these neat holes are ideal if your woodworking project call for a blind, flat-bottomed spot.

Sizes

Sizes of Spade Bits

Sizes

Spade drill bit: 0.25-inch to 1.50 inches is the size range. Hole saws are a better option for a more giant-diameter hole in wood. These, unfortunately, tend to bore conical holes and require drilling a pilot hole.

Forstner Drill Bits: The most commonly seen sizes of Forstner bits are 0.25-inch to 2.25-inches.

Materials

The Spade Bit: You can use spade bits on wood and soft metals like aluminum and brass. Still, they tend to leave burs on the exit hole.

Forstner Bit: For a cleaner hole in any material, a Forstner bit is a better choice. They work well on any wood. Like spade drill bits, you can use them on soft metal. When boring holes in metal, it is best to use a backer board.

Bi-metal hole saws are a better choice when drilling metal than either type of bit.

Speed

Spade Drill Bits: Spade drill bits are the faster choice between themselves and Forstner bits. Take note, though, that this speed comes at the cost of boring a perfect hole.

Forstner Drill Bits: To be honest, Forstner bits cut slower than any other type of hole cutter. It makes them a pain to use for deep hole drilling. Smooth holes come at a cost.

Price

The Spade Bits: It is the cheaper option between Forstner and spade bits. The high-speed steel, rather than high-carbon, used in their construction is slightly less expensive. In addition, spade bits are a much simpler design reducing their production costs.

Forstner Bits: It has a complex design requiring more detailed manufacturing work. The higher cost of the steel used in their construction makes them more expensive.

Keep in mind that there is a wide variety of Forstner and spade bits on the market. Depending on the quality, prices can vary greatly.

Conclusion:

There you have the basics of how Forstner and Spade drill bits stack up against each other. The significant differences lie in their work speed and the quality of holes they produce. Which is better for your particular woodworking project will depend on your goals. For more information, feel free to contact us.

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