I've seen lots of people use these bar clamps on YouTube when making bread boards or work benches. I've also seen people have problems with the metal bending or warping when used overnight.
Then I saw Paul Sellers point out that he just slides a piece of scrap wood inside the hollow tubing of the clamp to add extra strength and rigidity.
I figured if it's good enough for Mr. Sellers it's good enough for me.
Step 1: Measure
Measure the inside of the tube. These are 24" clamps, but the inside actually measured about 22 1/2". The height measured 1 1/16". I cut them a little over and planed off the extra later.
Step 2: Cuts
I have some busted up pallet wood in my firewood pile so I grabbed a few scraps of that. It's 1x4 fir. I marked my lines and made my cuts to end up with a stick about 22 1/2" x 1 1/16".
Step 3: Insert
I made sure the scrap just barely fit (trimming it down with a hand plane) and then tapped it in with a hammer.
I was actually surprised how well it fit. I'm not used to things fitting.
Step 4: Screw
The fit of the wood is tight enough that it would probably never come out on its own. But just to make sure I figured there's no harm in adding a screw at the end just to make sure it stays in place. I drilled a small pilot hole and used a short drywall screw.