I have a nice folding shooting bench that I purchased on sale at Cabela's last year for a South Dakota prairie dog hunt. It's not very heavy and it makes a pretty stable shooting platform. The table top and center column separate from the base and both pieces fold nearly flat so it was easy to transport and set up. I was mostly satisfied with the purchase, especially since I got it at 40% off, but I did have one complaint. The table was set at a fixed elevation. If you were shooting up hill or down hill you couldn't adjust the angle of the table. After some consideration, I decided to remedy this shortcoming.
Step 1: Fixed Length Table Support
The table pivots on a center column and is supported by an 1-1/4" square tube fixed length support arm. This support arm is pinned to a bracket at the center of the table and fastened to the center column by a hinge bolt. My solution was to remove the fixed length support arm and replace it with an adjustable one.
Step 2: Removing the Factory Support Arm
To make my intended modification I first needed to remove the factory support arm. This was rather simple as all I had to do was remove one pin and one bolt.
Step 3: Prepare Support Bracket for the New Arm
I chose a 3-point tractor hitch top link to replace the factory support arm. At first glance it looked like this would be an easy swap. But, like most projects it took a little more work than was expected. Still, it was not too difficult. The factory arm was held in place by a 5/16" pin and a 5/6" hinge bolt. The pivot point eyes on the top link were 5/8: diameter. So, the first thing I had to do was find bushings for the top link eyes. I couldn't find any off the shelf bushings at my local hardware store that were 5/8" OD and 5/16" ID so I decided to fabricate them. I ended up buying a 5/8" diameter nylon rod from Fastenal for the bushing stock. The mounting brackets were about 1-1/4" wide so I cut 2 pieces of rod that length and bored a 5/16" hole through both pieces. After a little sanding both bushings fit perfectly into the top link eyes and the brackets. There was just one problem...
Step 4: Fitting the Adjustable Support
The support arm mounting bracket on the center column was made from 1-1/4" C-channel. The bolt hole was drilled in the center of the bracket. That makes the pivot radius in the bracket about 5/8". The outside diameter of the top link eye is about 1-7/8" which requires a pivot radius of about 15/16". So, to make the top link fit a little modification of the bracket was required. An angle grinder made quick work of the bracket modification and we were back in business.
Step 5: Installation Complete
After notching the center column mounting bracket the installation was quite easy.
Step 6: Testing the Installation
The table section was placed back on the base and and the elevation adjustments were smooth and easy. The table is still a solid platform to shoot from. All that is left to do it paint the new parts and go to the range.