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Cam-out happens when a screwdriver bit climbs out of a screw’s recess instead of turning the screw. With an impact driver, that can happen quickly: the bit slips, chews up the head, and may scratch the workpiece or injure your hand. The fix is usually not more torque. It is a better-fitting bit, steady pressure, and a setup that keeps the bit square to the screw.
What we cover
Why impact drivers cam out
An impact driver applies rotation in short bursts. That pulsing action is useful for driving fasteners, but it can magnify a poor connection between bit and screw. A worn, undersized, or mismatched bit has less contact with the recess, so it can ride up when the driver hits. Holding the tool at an angle or using too little forward pressure makes the problem worse.
Fastener design matters, too. Phillips screws are intended to cam out under high torque, which can help limit over-tightening in some applications. That feature also makes them more prone to slipping than a well-matched square-drive or Torx-style fastener. Damaged recesses and soft, low-quality screws are especially troublesome.
Match the bit to the screw
Use the exact drive type and size called for by the fastener. A bit that almost fits is not a good fit. For example, a Phillips #2 bit may seem close to a #3 recess, but it will contact the screw poorly and can quickly strip it. Push the bit into the recess by hand before driving: it should seat fully, with little side-to-side movement.
For routine wood fastening, Torx and square-drive screws often provide a more secure connection than Phillips. If you are buying fasteners for a project, choose the drive that suits the job and buy bits in the matching size. A set of quality impact-rated driver bits in common drive sizes is useful when you work with mixed fasteners. “Impact-rated” bits are made to tolerate repeated impacts better than many standard bits, but they still wear and can cam out if the fit is wrong.
Inspect the tip before use. Rounded edges, a twisted shank, or a polished, worn-looking point are signs to replace it. A fresh bit is inexpensive compared with a damaged screw head or a ruined workpiece.
Set up the driver and workpiece
Keep the driver aligned with the screw’s axis. Even a slight tilt reduces contact inside the recess. For long screws or awkward locations, use a longer bit holder or a right-angle attachment only if it helps you keep the tool straight; an extension that wobbles can make control worse.
Seat the screw before applying power. Start it by hand for a turn or two, or use a pilot hole when the material or screw size calls for one. In hardwood, near an edge, or with a thick screw, a pilot hole reduces the force needed to start the fastener and lowers the risk of splitting. Use a countersink if the screw head needs to sit flush in a material that would otherwise resist it.
Grip the tool firmly and press forward in line with the screw. The goal is enough pressure to keep the bit fully seated, not so much that you cannot control the driver. Brace the workpiece so it cannot shift. If the screw starts to slip, stop immediately; continuing to trigger the driver often rounds the recess further.
Control speed and torque
Start with a low-speed setting or a gentler trigger pull, especially on small screws, cabinet hardware, and screws going into soft material. Once the screw is seated and turning cleanly, increase speed if needed. Many impact drivers have speed or assist modes; these can make delicate work easier, but they do not replace a correctly sized bit or a straight approach.
Back off as the head approaches the surface. Impact drivers can drive a fastener below the surface or snap a small screw if you keep holding the trigger after it is seated. For final tightening on delicate work, a cordless drill with a clutch may offer finer control. It is slower, but the clutch can stop driving at a set resistance. An impact driver is a better choice for longer or larger fasteners where its compact size and high driving force are useful.
Choose the right approach
| Situation | Better approach | Trade-off |
|---|---|---|
| Long screws into framing lumber | Impact-rated bit, straight alignment, steady forward pressure | Fast driving, but easy to overdrive the head |
| Small screws or delicate hardware | Low speed, light trigger, or a drill with a clutch | More control, but slower than impact driving |
| Repeated slipping with Phillips screws | Check bit size and wear; use a matching drive fastener when practical | May require changing the screws or keeping another bit on hand |
| Screw will not start in hardwood | Make an appropriately sized pilot hole | Adds a step, but lowers driving force and splitting risk |
When to change bits or tools
Replace the bit if it slips in a clean, undamaged screw recess despite correct alignment and pressure. If a new, correctly sized bit still will not grip, the screw head may already be damaged. Stop rather than trying repeatedly; use a screw extractor or another removal method if the fastener must come out.
For general fastening, a small selection of good bits is usually a better purchase than a large, cheap assortment. If you often work with different screw types, a compact impact-rated bit set can cover common sizes without taking much space. A budget set is fine for occasional household jobs, provided the tips fit accurately and you replace worn bits promptly.
If cam-out keeps happening on one project, check the whole setup: screw drive, bit size, material, pilot hole, tool angle, and speed. More force is rarely the first fix. A clean fit and controlled start prevent most slips—and preserve both the screw head and the surface around it.