Spade Bits for Impact Drivers
Spade bits are the one big-hole cutter an impact driver handles well. Pick the right tip and use a little technique, and they punch through framing fast.
We research tools from manufacturer specs and long-term owner feedback. If you buy through our Amazon links we may earn a commission at no extra cost to you. How we make money.
Spade bits for an impact driver work well in wood from about 1/4 to 1-1/2 inch. Buy a hex-shank, impact-rated set and choose threaded-tip spade bits, which pull themselves through the cut and suit an impact driver's hammering. Run at a middle speed, keep the driver straight, ease off near breakthrough and finish from the back side when the exit face matters. For holes over 1-1/2 inch or deep holes in posts, use an auger or a drill.
On this page
Why spade bits suit an impact driver
A spade bit, also called a paddle bit, is a flat blade with two cutting edges, a center point and sometimes spurs on the outer corners. It cuts wood aggressively and clears chips well in shallow holes. Most come with a 1/4-inch hex shank, so they drop straight into an impact driver's collet.
That aggression is why they pair well with an impact driver. When a large bit loads up in a drill, the drill stalls or twists your wrist. An impact driver switches to hammering and keeps turning, with little kickback to your arm. For running cable or pipe through a wall of studs, it is one of the fastest setups there is.
If you want the wider picture on drilling, read can you drill with an impact driver. For other cutter types, see drill bits for impact drivers.
Threaded tip vs plain spade bits
| Feature | Plain point | Threaded tip |
|---|---|---|
| How it feeds | You push it through | The screw tip pulls it into the wood |
| Speed in framing | Good | Faster, less pressure needed |
| Control | More control; you set the feed rate | Can grab hard in knots or at breakthrough |
| Best use | Shallow holes, softwood, careful work | Production holes through studs and plates |
| Cost | Lower | Higher |
Threaded-tip designs, such as the Bosch Daredevil line, have become the default choice for impact drivers because the driver supplies the rotation while the tip supplies the feed. You hold the tool steady and it walks through. The trade-off is grab: when the tip bites into a knot, the bit wants to pull itself in faster than the edges can cut.
Self-feeding bits
Large self-feed bits with a screw point and saw-tooth rim are made for heavy right-angle drills. Some smaller hex-shank versions exist, but large diameters generate more resistance than an impact driver handles smoothly. Check the bit's listing to confirm it is approved for impact drivers.
Which spade bit sizes work in an impact driver
| Size | Typical use | Impact driver fit |
|---|---|---|
| 1/4 to 1/2 inch | Small wire runs, dowel and bolt holes | Easy, but a twist or auger bit is often cleaner |
| 5/8 to 1 inch | Cable runs, small pipe, rope and lag clearance | The sweet spot |
| 1-1/8 to 1-1/2 inch | Plumbing, conduit, multiple cables | Works with a sharp bit and steady technique |
| Over 1-1/2 inch | Large pipe, drains | Use a self-feed bit or hole saw in a drill |
Most sets cover 1/4 to 1-1/2 inch. Standard bits are about 6 inches long; extensions and longer bits help when you drill through a run of studs from one spot. The hole saw guide covers bigger cutouts.
Threaded-tip spade sets on Amazon Spade bit extensions
Technique: clean, fast holes
- Mark the center and press the point in before you pull the trigger. The point is the guide.
- Start slow until the outer spurs score a circle, then add speed. A middle speed setting is usually best. See speed settings and modes.
- Keep the driver square to the face. Spade bits are long and thin, so an angled start bends the bit or makes an oval hole.
- Pull back to clear chips every inch or so in deep holes. Packed chips cause heat and grab.
- Ease off as the point exits. This is where blowout and grab happen.
- Hold tight with both hands on threaded tips, especially in knotty lumber.
How to avoid blowout
Blowout is the splintered exit hole you get when the cutting edges punch through unsupported fibers. In framing it rarely matters. In trim, cabinets or visible lumber it ruins the piece.
- Drill from both sides. Drill until the point just pokes through, then flip and finish from the back using that hole as a guide.
- Clamp a backer board to the exit side. The bit cuts into scrap instead of tearing your workpiece.
- Use spurred bits. The outer spurs score the fibers before the flat edges cut.
- Slow down at the end. Lower speed and lighter pressure for the last 1/4 inch.
Common spade bit mistakes and fixes
| Mistake | What happens | Fix |
|---|---|---|
| Full speed from the start | Point skates, hole starts off-center | Start slow until the spurs score the circle |
| Leaning on the tool | Constant hammering, rough hole, bent bit | Let the tip feed; use light, steady pressure |
| Never clearing chips | Heat, burning, bit binds in deep holes | Pull back every inch or so |
| Prying to straighten a hole | Bent shank, wobble on the next hole | Back out and restart square |
| Using a dull bit | Slow cutting, smoke, more grab | File the edges or replace the bit |
| Long extension stack | Whip and wobble at the tip | Use the shortest extension that reaches |
Spade, auger or hole saw?
Spade bits are the fastest and cheapest choice for holes through single studs and plates, up to about 1-1/2 inch. Auger bits cost more but clear chips through deep holes, such as doubled top plates or 4x4 posts, and they track straighter over a long run. Hole saws make cleaner holes at large sizes but are the worst match for an impact driver. If you drill the same 3/4 or 1-inch hole all day, a threaded-tip spade bit in an impact driver is hard to beat. If you drill deep holes through posts, buy one good hex-shank auger.
Buying spade bits for an impact driver
Look for a 1/4-inch hex shank, an impact-rated or impact-ready label, and a sturdy shank where the hex meets the blade. That joint is where cheap bits snap. The steel differences are explained in impact-rated vs regular bits.
Weaknesses to know before you buy:
- Spade bits leave rough holes compared with Forstner bits or augers.
- They bend if you lever them sideways.
- Threaded tips are hard to resharpen, so damaged tips mean a new bit.
- Large sets include sizes you will rarely use; buying individual 3/4, 7/8 and 1-inch bits can make more sense.
Safety: a spade bit that grabs can wrench the driver in your hand. Wear eye protection, brace your stance and keep your free hand away from the exit side of the board. Check for hidden wires and pipes before drilling into walls. See impact driver safety.
Frequently asked questions
What size spade bit for running wire through studs?
It depends on the cable or conduit and local code, but 3/4 to 1 inch is common for a few runs of residential cable, and larger sizes for conduit or plumbing. Check bored-hole limits for your studs and joists before drilling large holes.
Why does my spade bit wobble?
Common causes are a bent bit, a worn collet, a long extension stack or starting the hole at an angle. Spade bits are long and thin, so any play is magnified at the tip. Replace bent bits and keep extensions short.
Can you sharpen spade bits?
Yes. A few light passes with a fine file on the cutting edges and the spur restore most bits. Keep the original angles and file both sides evenly. Threaded tips are harder to restore, so a badly damaged tip usually means a new bit.
Are spade bits good for hardwood?
They work but cut slower and can burn. Use a sharp bit, a lower speed and frequent pull-outs to clear chips. For clean, flat-bottomed holes in furniture hardwood, a Forstner bit in a drill or drill press is the better tool.