What is Cam Out and how to avoid it?

Cam breakout occurs when your screwdriver bit slips out of the screw head as it is turned. It's annoying, can damage fastener heads or drill bits, and cause more curses than most of us care to admit.

What Causes Cam Out?

Unfortunately, it's not uncommon to cam out screws, especially when using Phillips head screws. These taper toward the center, like a driver bit.

When you pull the trigger on the driver, the rotation pushes on the inside of the screw, which turns it. When you're not applying enough downforce to engage the fastener, or you're entering the fastener at an angle, the driver's torque pushes the bit up and out.

Because drill bits and impact drivers spin at such high speeds, the bit will travel in and out of the head of the fastener hundreds of times before you let go of the trigger.

Cheap soft screws will stick out their heads, making it very difficult to finish the drive or to back them out. Sometimes the bit is a softer metal and it starts to round. Another possibility is that both materials are so hard that the drill tip will snap off.

Use the correct drill to avoid cam out

One way to keep the drill from coming off the fastener is to make sure you are using the correct size drill. Matching the bit to the screw you will be turning can make all the difference. Plug the bits in and wiggle a bit while you check. Shouldn't be playing much. If available, move on to the next larger size.

For example, check the dimensions on the side of the box before installing any screws. If you are using a #2 Phillips head, you will need a #2 Phillips driver. These will fit very snugly against the screws. A quality drill and fastener pair will barely move.

You also need to check the drill itself. Even with proper use, they can wear out and round out over time. Worn bits are easier to pull out than new ones.

Maintain balance to reduce cam misalignment

Keep the drill straight up and down as you drive. Any tilt will transfer force to the screw unevenly. This will eventually cause the bit to dislodge and dislodge.

When using a handheld screwdriver, there needs to be a balance between pushing and turning forces. Basically, you can push a drill or screwdriver into a screw with some force, but be more careful when turning it. NBK's personnel recommend applying a 70%/30% thrust to steering ratio.

replace with a new screw

There are quite a few drill and fastener styles that can help keep the cam from coming off. Square, Star and Torx bits and screws have more surface area and grip to avoid stripping and transfer more torque more easily.

Instead of tapered grooves and four surface area points, the Torx design provides more contact area to grip while maintaining a consistent head depth. As long as you keep the bit going in straight, it's almost impossible to cam with these hexagonal bits.

You can also use hex head fasteners and, in many applications, a nut driver or socket. It's easier to keep the two interacting by wrapping around the head instead of sliding into it.

in conclusion

When it comes to camming with screws or fasteners, you can experiment with any tool. From hand screwdrivers to power drills, the idea is to maintain positive pressure so the bit stays in place while you drive. When using a drill, you need to apply a lot of force. Impact drivers make this easier thanks to the rotary action of these tools.

In the end, good technique and the right fasteners and bits can make all the difference.

Like the impact driver in the photo? Here’s the Makita XDT16 from our head-to-head review of the best impact drivers. Check out our in-depth review of it here!