Shooting Bench Elevation Modification

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.

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.

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.

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...

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.

After notching the center column mounting bracket the installation was quite easy.

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.