DIY Adjustable Jack Posts

3 inch Jack Post Adjuster that can adjust up to 4 inches in height. 3-1/2 Inch Jack Post Adjuster that can adjust up to 4 inches in height. We typically cut our pipe when building a jack post 3 inches smaller then the size of the post needed. This allows the Plate and Adjuster to fit snugly. Example: If you need a 75 inch post cut the pipe 72 inches.