The single biggest reason screws strip is the driver slipping out of the head under torque, a problem called cam-out. Preventing it comes down to three things: using the right size driver, applying strong downward pressure, and breaking the screw’s grip before you try to turn it. Here’s how to do all three, plus what to try if the head is already starting to wear.
Match the Driver to the Screw Exactly
A screwdriver that’s even one size too small will sit loosely in the recess, concentrating force on the edges of the cross instead of across the full contact area. That’s how stripping starts. Phillips drivers come in sizes that correspond to specific screw ranges: a PH0 fits #0 and #1 screws, PH1 fits #2 through #4, PH2 fits #5 through #9, and PH3 fits #10 through #16. If you’re reaching for a PH2 out of habit for every screw in the house, you’re probably using the wrong size half the time.
The tip width differences are small but matter enormously. A PH1 tip measures roughly 1.3 to 1.4 mm across, while a PH2 is about 2.2 to 2.3 mm. Dropping from a PH2 to a PH1 on a screw that needs the larger driver means you’re making contact with a fraction of the available surface. The fix is simple: push the driver into the screw head before you turn it. If there’s any wobble or play, go up or down a size until the fit is snug.
For flat-head (slotted) screws, the blade should fill the slot’s full width and sit flush at the bottom. A blade that’s too narrow will rock side to side and chew up the slot walls. A blade that’s too thick won’t seat fully.
Push Down Hard, Then Turn Slowly
Cam-out happens when rotational force overcomes the downward pressure holding the driver in the recess. As a screwdriver tip wears or a screw head corrodes, the geometry shifts so that turning force actually pushes the driver upward and out of the head. A worn driver can require roughly 35% more downward pressure to stay seated compared to a new one. The practical takeaway: press down firmly before you even start turning, and keep pressing throughout the rotation.
Turn slowly and deliberately. Quick, jerky motions give the driver a chance to skip out of the recess between strokes. If you’re using a power drill, set it to the lowest speed and highest torque setting. Better yet, switch to a hand screwdriver for stubborn screws. You get far more feedback through your palm and can feel the instant the driver starts to slip, which lets you stop before damage happens.
Break the Bond Before You Turn
A screw that hasn’t moved in years may be held by more than thread friction. Corrosion between the screw and the surrounding material essentially welds them together. Trying to muscle through that bond with rotational force alone is the fastest way to strip the head. Break the bond first.
Penetrating Oil
Spray a penetrating lubricant directly onto the screw head and let it soak for several minutes. The oil wicks into the microscopic gaps between the threads and dissolves corrosion from the inside out. For badly rusted screws, apply a second round and wait again. Patience here saves the screw head. Tapping the screw lightly with a hammer after applying the oil can help the liquid travel deeper into the threads by vibrating open micro-channels in the rust.
Heat
Metal expands when heated. Applying heat directly to the area around a stuck screw causes the surrounding material to expand slightly, which can crack the corrosion seal and create just enough clearance for the screw to turn. A heat gun set between 400 and 800°F (204 to 427°C) is the right range for loosening rusted fasteners or softening thread-locking adhesive. Hold the heat on the area for 20 to 30 seconds, then attempt removal while the metal is still warm. Don’t use penetrating oil and heat together, as many penetrating oils are flammable.
Impact
A manual impact driver is one of the most effective tools for stuck screws. You insert a bit, place it in the screw head, and strike the back of the driver with a hammer. The internal mechanism converts that straight-line hammer blow into simultaneous downward pressure and rotational torque. A coil spring inside the driver compresses and twists at the same time, then releases that stored energy as a sharp rotational hit. This delivers a burst of turning force while pushing the bit deeper into the screw, which is the exact opposite of what happens during cam-out. Manual impact drivers cost around $15 to $30 and work on screws that no amount of hand-turning will budge.
Increase Grip on a Worn Head
If the screw head is already showing signs of wear but isn’t fully stripped, you can recover grip with a few tricks.
- Rubber band: Place a wide rubber band flat over the screw head, then push your screwdriver through the rubber into the recess. The rubber is malleable enough to fill in damaged crevices, and its high friction coefficient keeps the driver from slipping. It essentially creates a temporary new drive surface that grips both the tool and the screw at the same time. Use the widest band you have for maximum coverage.
- Steel wool: Pack a small piece of steel wool into the screw recess before inserting the driver. The fine metal fibers fill gaps and add friction in a similar way to the rubber band method, but with a stiffer material that holds up slightly better under torque.
- Valve grinding compound: This abrasive paste, sold at auto parts stores, increases friction between two metal surfaces. Dab a small amount onto the screwdriver tip before inserting it. The grit bites into both the tool and the screw head, resisting the slippage that causes cam-out.
All three methods work on the same principle: filling the gap between a worn screw head and the driver with material that adds friction. They’re temporary fixes that buy you enough grip for one removal, not long-term solutions.
Prevent Problems on Future Screws
The easiest screw to loosen is one that was installed with future removal in mind. Anti-seize compound, applied as a thin layer to threads before driving, prevents the corrosion and galling that make screws seize over time. It’s especially useful when joining different metals (like a steel screw into aluminum), where galvanic corrosion can bond the threads aggressively. Anti-seize products work by placing a lubricating barrier between the metal surfaces that withstands heat, moisture, and vibration.
Different formulations hold up at different temperatures. Graphite-based compounds remain effective up to about 600°C, while other solid lubricants break down at lower thresholds. For most household and automotive applications, a general-purpose anti-seize is more than adequate. Apply it sparingly to the threads only, not the screw head, and wipe away any excess.
Beyond anti-seize, two habits prevent most stripping: always use the correct size driver, and replace worn screwdriver tips. A driver that’s been used thousands of times has rounded edges that no longer match the original geometry, and that wear is invisible to the naked eye. Swapping to a fresh bit costs almost nothing and eliminates one of the most common causes of cam-out.