Double tree trunks form a crevice or crotch from a single main leader trunk. Over time, the double tree trunk may pull apart, especially when heavy snow or ice forms on the upper limbs. The damage from this split will cause a catastrophic separation of the double trunk. Prevent this split by installing a long bolt through the center of both tree trunks. The holding force of the bolt keeps the trunks from separating and pulling away from each other.
Install the 18-inch-long wood boring bit into the heavy-duty drill motor.
Select the location on the double trunk to drill the hole. Choose the position for drilling the hole by finding the vertical center point of the crevice or crotch on the double trunk.
Drill out the boring hole. You may have to move the drill to the opposite side of the double trunk to make a hole clear through both tree trunks.
Screw one of the nuts on the end of the 1- inch all-thread bolt. Keep the end of the nut in line with the end of the all-thread bolt. Fit the washer onto the all-thread bolt up against the nut. The length of the bolt must be 6 inches longer than the overall span of the double tree trunk.
Drive the all-thread bolt through the boring hole. Use the nut end as the striking surface with the hammer. Mate the surface of tree bark with the flat washer.
Place the second washer over the bolt and against the tree. Screw the nut onto the protruding piece of bolt. Tighten both nuts with the crescent wrench.
Cut off the excess protruding all-thread bolt with the metal hacksaw. Re-tighten the nuts regularly over the next few months. The bark from the tree will eventually cover the nuts and bolt.