How to Fracture a Lag Screw

What NOT to Do:

• 1

  Avoid ease of use waxes such as Johnson's that can help the screw stick to the driver as you first prepare to drive it into the wood. Naked drilling increases bolt slippage, and assists the metal weakening that is the fist step toward fracturing a screw.

• 2

  Use the softest metal possible when drilling. For example, although stainless steel screws are preferred for their smoothness and ease of drilling, they are actually softer than galvanized steel and more prone to fracturing.

• 3

  Set the torque of your screw driver as high as you possibly can. This will put the maximum amount of shear on the metal as you are driving it through the wood. You also may forgo the drilling of a clearance hole, or create a much smaller clearance hole than the hole you will finally be drilling. Both the width and the length of the clearance hole should be smaller than the screw you will be sending.

• 4

  Hardwoods aid in the fracturing of screws much more easily than softer woods. Try your screw in a nice wood like cedar or mahogany for maximum fracturing, and avoid softer woods like balsa or soft pine.