Cribbing Rule

Paul Rolandelli demonstrates a cribbing rule

By Paul Rolandelli

Start by selecting a substantial point to support, like the truck frame rail rather than something easy to photograph, like this bumper.

Place one end of the flexible rule on the ground directly under the point that you want to build the box crib. Holding the rule between your thumb and pointer finger, slide your fingers up the rule until you contact the frame rail.

Pinch the rule at the point where your fingers holding the rule contacts the frame. Move out of the pinch point/collapse zone and look at the rule. Work backwards down the rule to determine whether to start with end grain or side grain on the lowest base level.

In the above picture, the white area just below the bumper would be filled with wedges placed on top of the solid 4 x 4 placed with the red end grain showing. Continue alternating down the rule until the ground is reached.

Bumper

White area fill with wedges.

Red area end grain of 4 x 4.

White area side grain of 4 x 4.

Red area end grain of 4 x 4.

White area side grain of 4 x 4.

Red area end grain of 4 x 4.

The rule allows one to determine whether to start the base layer of 4x4s with end grain or side grain showing. You never have try to turn a stack of loose cribbing to get the top layer perpendicular to the frame rail you are cribbing.

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Never paint the sides of your cribbing–it can hide cracks and makes the cribbing slippery when wet compared to unpainted wood. If your company uses 6 x 6 cribbing to build entire cribbing stacks, make a 6 x 6 ruler from lumber strapping.

If you want to start the cribbing stack with 6 x 6s and change to 4 x 4s, place your 6 x 6s and then measure the distance from the top of the 6 x 6s to the underside of the frame rail. Determining which way the lowest 4 x 4 should face (end grain or side grain) will show you which way the 6 x 6s must be laid.

Don’t forget to de-rate the cribbing stack from 15,000 pounds per 6 x 6 contact point to 6,000 pounds per 4 x 4 contact point.

Lastly, although in this example the red sections of the rule were for end grain, in the next example the white section of the rule may be the end grain. It can change each time the rule is used.

Paul Rolandelli (a.k.a. C. Paul MacGyver) is an active riding member of Elkridge (MD) Volunteer Fire Company. He has numerous Pro Board Certifications, including Fire, Rescue, Inspector, and Instructor I & II  He has prior published articles and was awarded a U.S. patent for an emergency vehicle safety seat. He graduated from the University of Maryland Baltimore County’s Emergency Health Services program in 1983.  

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