7 Big-Hole And Deep-Hole Wood Bits
Drilling large holes or deep holes in wood requires specialized bits designed for these specific tasks. Whether you’re building furniture, installing door hardware, or working on a log cabin, having the right bit makes all the difference between a clean, precise hole and a frustrating, splintered mess. This article explores the various types of wood bits specifically designed for creating big holes and drilling deep into wood, helping you choose the right tool for your next woodworking project.
When working with wood, the quality of your holes directly impacts the quality of your finished project. Using the wrong bit can lead to tear-out, inaccurate dimensions, or bits getting stuck halfway through. Let’s examine the best options for both large-diameter and deep-hole applications, their advantages, and when to use each type.
1. Hole Saws
Hole saws are cylindrical cutting tools designed specifically for creating large, clean holes in wood and other materials.
Key Features:
- Cylindrical saw with teeth around the perimeter
- Available in diameters ranging from ¾” to 6″ or larger
- Creates clean holes with minimal splintering
- Includes a pilot bit in the center for guidance
- Preserves the cut-out core, which can be useful for some projects
Pros and Cons of Hole Saws
| Pros | Cons |
|---|---|
| Creates very clean holes with minimal tear-out | Not ideal for deep holes (typically limited to material thickness of 1-2″) |
| Wide range of available sizes | Can get clogged with sawdust during use |
| Preserves the cut-out piece (useful for plugs) | More expensive than paddle bits |
| Works well with portable drills | Slower cutting speed than some alternatives |
Hole saws excel at creating clean holes for doorknobs, pipe passages, and recessed lighting. They’re particularly useful when you need a precise diameter and clean edges, such as when installing hardware or creating decorative elements.
2. Forstner Bits
Forstner bits are precision cutting tools designed to bore flat-bottomed holes with exceptionally clean edges.
Key Features:
- Flat cutting edges with a center guide point
- Available in sizes from ¼” up to 4″ in diameter
- Creates extremely clean, flat-bottomed holes
- Can drill overlapping holes and partial holes at edges
- Produces minimal tear-out even in veneer and plywood
Pros and Cons of Forstner Bits
| Pros | Cons |
|---|---|
| Creates the cleanest holes of any bit type | More expensive than other bit types |
| Excellent for precise, flat-bottomed holes | Requires more power to operate effectively |
| Works well for pocket holes and angled drilling | Not ideal for handheld drilling of very large holes |
| Can drill partial holes at edges | Slower cutting speed, especially in hardwoods |
Forstner bits are the go-to choice for furniture makers and fine woodworking. They excel at creating hinge recesses, counterbores for screws, and any application requiring a perfectly clean hole with a flat bottom. For the cleanest results, they’re best used in a drill press, though smaller sizes can be used with handheld drills.
3. Spade Bits (Paddle Bits)
Spade bits, also called paddle bits, feature a flat, paddle-shaped design with a center point and two cutting edges.
Key Features:
- Flat, paddle-shaped design with a center spur
- Available in sizes from ¼” to 1½” typically
- Inexpensive and widely available
- Fast cutting speed
- Some models feature self-feeding tips
Pros and Cons of Spade Bits
| Pros | Cons |
|---|---|
| Inexpensive and readily available | Creates rougher holes with more tear-out |
| Fast cutting speed | Not suitable for fine woodworking projects |
| Works well for rough construction | Can cause splintering when exiting the material |
| Effective for electrical and plumbing rough-ins | Less precise than Forstner bits or hole saws |
Spade bits are perfect for rough construction work, such as drilling holes for electrical wiring or plumbing pipes. They cut quickly but sacrifice some cleanliness. For the best results with spade bits, drill slowly when entering and exiting the material to minimize tear-out, and place a sacrificial board behind your workpiece when drilling through-holes.
4. Auger Bits
Auger bits are designed specifically for drilling deep holes in wood, featuring a spiral flute that efficiently removes chips as you drill.
Key Features:
- Long spiral design with a screw tip
- Available in lengths up to 18″ or more
- Self-feeding screw tip pulls the bit into the wood
- Deep flutes efficiently remove chips from the hole
- Available in diameters from ¼” to 1½”
Pros and Cons of Auger Bits
| Pros | Cons |
|---|---|
| Excellent for deep holes | Not designed for clean, finished holes |
| Self-feeding design requires less pressure | Can be difficult to control in portable drills |
| Efficient chip removal prevents binding | Limited size range compared to other bit types |
| Ideal for log cabin building and timber framing | Requires more torque than other bits |
Auger bits are the traditional choice for drilling deep holes in timber framing, log cabin construction, and other applications requiring deep penetration. Their self-feeding design and efficient chip evacuation make them ideal for drilling straight, deep holes without binding or overheating.
5. Extension Bits and Accessories
For extremely deep holes, standard bits often aren’t long enough. Extension accessories can help reach greater depths.
Key Features:
- Extends the reach of standard drill bits
- Available in various lengths from 6″ to 36″ or more
- Can be used with multiple bit types
- Some include stabilizing features for straighter holes
- Often used with spade bits or auger bits
Pros and Cons of Extension Bits
| Pros | Cons |
|---|---|
| Allows drilling much deeper than standard bits | More flex and potential for wandering |
| Works with bits you already own | Requires more power and control |
| Versatile for different applications | Can be difficult to start holes accurately |
| Cost-effective solution for occasional deep drilling | Not as rigid as dedicated long bits |
When using extension bits, start with a standard bit to create a pilot hole that will guide your extended bit. This helps prevent wandering and ensures a straighter hole. Also, drill slowly and back out frequently to clear chips, which is especially important with extended bits where chip evacuation is more challenging.
6. Self-Feed Bits
Self-feed bits combine elements of hole saws and auger bits, designed for efficiently drilling large holes with power drills.
Key Features:
- Center feed screw with outer cutting teeth
- Available in sizes from 1″ to 4″ or larger
- Designed for use with high-torque drills
- Cuts faster than hole saws
- Often used by electricians and plumbers
Pros and Cons of Self-Feed Bits
| Pros | Cons |
|---|---|
| Very fast cutting speed | Requires a powerful drill with side handle |
| Efficient for multiple holes | Can be aggressive and difficult to control |
| Good for construction applications | Creates rougher holes than Forstner bits |
| Available in large diameters | Not suitable for fine woodworking |
Self-feed bits are commonly used by professionals who need to create many large holes quickly, such as electricians running conduit or plumbers installing pipes. They’re extremely efficient but require a powerful drill with a side handle to control the torque safely.
7. Step Drill Bits
While primarily designed for metal, step drill bits can be useful for creating precise holes in thin wood and plywood.
Key Features:
- Cone-shaped with multiple diameter steps
- Creates holes from ⅛” up to 1½” with a single bit
- Produces clean holes in thin material
- Self-centering design
- Less likely to cause splintering in thin plywood
Pros and Cons of Step Drill Bits
| Pros | Cons |
|---|---|
| Multiple hole sizes in one bit | Only suitable for thin materials (up to ¾”) |
| Creates clean holes in thin plywood | Not designed specifically for wood |
| Less likely to cause tear-out than twist bits | More expensive than basic wood bits |
| Self-centering design improves accuracy | Limited to smaller diameters |
Step drill bits are excellent for creating clean holes in thin plywood, particleboard, and MDF, especially for electronics projects or cabinet making where thin materials are common. They’re not suitable for deep holes but excel at creating precise openings in sheet goods.
Comparison of Big-Hole and Deep-Hole Wood Bits
| Bit Type | Diameter Range | Max Depth | Hole Quality | Best Applications | Relative Cost |
|---|---|---|---|---|---|
| Hole Saw | ¾” to 6″+ | 1-2″ | Very Good | Door hardware, pipe holes | Medium |
| Forstner Bit | ¼” to 4″ | 1-2″ | Excellent | Furniture, hinges, fine woodworking | High |
| Spade Bit | ¼” to 1½” | 6″ (standard) | Fair | Rough construction, electrical work | Low |
| Auger Bit | ¼” to 1½” | 6-18″+ | Good | Log cabins, timber framing, deep holes | Medium |
| Self-Feed Bit | 1″ to 4″+ | 1-3″ | Fair | Construction, multiple holes | Medium-High |
| Step Drill Bit | ⅛” to 1½” | ¾” max | Very Good (thin material) | Thin plywood, sheet goods | Medium |
| Extension Bits | Varies | 6-36″+ | Varies | Extra-deep holes | Low (accessory) |
Tips for Drilling Big and Deep Holes in Wood
For Big Holes:
- Use the right speed – Larger bits require slower speeds to prevent burning and maintain control
- Drill a pilot hole – Start with a small bit to guide larger bits accurately
- Back the workpiece – Place scrap wood behind your workpiece to prevent tear-out when the bit exits
- Use steady pressure – Let the bit do the work; excessive pressure can cause binding or inaccurate holes
- Consider a drill press – For precision holes, especially with Forstner bits, a drill press provides better control
For Deep Holes:
- Clear chips frequently – Back the bit out regularly to remove sawdust and prevent binding
- Use cutting oil or wax – A light lubricant can reduce friction and heat in deep holes
- Start straight – Ensure the bit is perfectly perpendicular to the surface when starting
- Use guides for accuracy – For extremely deep holes, consider using a jig or guide to maintain straightness
- Choose bits with chip-clearing features – Auger bits and others with deep flutes remove chips more efficiently
Choosing the Right Bit for Your Project
When selecting a bit for your woodworking project, consider these factors:
- Hole diameter – Match the bit size to your required hole size
- Hole depth – For depths greater than 2″, consider specialized deep-drilling bits
- Material – Hardwoods require sharper, higher-quality bits than softwoods
- Finish quality – For visible holes, choose bits that produce cleaner cuts
- Available tools – Some bits work better with drill presses than handheld drills
- Number of holes – For multiple holes, invest in higher-quality bits that stay sharp longer
For most woodworkers, having a combination of bit types provides the versatility needed for various projects. A basic set might include spade bits for rough work, a hole saw kit for medium to large holes, and a few Forstner bits for precision applications.
Summary
Drilling big holes and deep holes in wood requires specialized bits designed for these specific tasks. For large, clean holes in furniture and fine woodworking, Forstner bits offer unmatched precision. Hole saws provide an excellent balance of hole quality and affordability for medium-depth large holes. For deep drilling, auger bits remain the traditional favorite, especially for timber framing and log construction.
When working on projects requiring both large diameter and significant depth, consider your approach carefully—sometimes a combination of techniques works best, such as starting with a Forstner bit for a clean entrance and switching to an auger bit for depth. With the right bits and proper technique, you can create precise, clean holes of any size and depth in your woodworking projects.