I am building a workbench based on the Steevo bench on garagejournal for those familiar. He used leveling feet and sq tube inserts from JW Winco. I plan on doing the same. On the JW Winco site, it says that the insert I'm interested in has a static load (for 3/8-16 thread) of 1349 lbf. Why is the unit lbf? Or, asked another way, why isn't the unit just lb? This has totally befuddled me.
Wut? It's absolutely critical information. The insert can only take so much force before it fails. I'm not sure what the table being static has to do with anything. The problem is with the imperial measurement system that differentiates between lbm and lbf. It's stupid and I hate it, but that doesn't make it less relevant.
The bench is more overbuilt than the adjuster inserts. Anything like this that I have done has just been a nut ground down to fit in the inside of the tubing and welded in place with a bolt used as the adjuster. Are you using the premanufactured adjusters for appearance or for the rubber feet that will not mark the floor?
Might just go the route you describe. While they would look finished, they def add expense. Either way, gonna have to wait until I get steel. The yard I've been to in the past had no 2x2 sq tube less than 3/16 wall. I was thinking 14 ga.
Let me explain further. lbf and lb are interchangeable, but lbf and lbm are not. lbf is the proper designation for a unit of force versus lbm which is a unit of mass. On earth 1 lbm will have a weight of 1 lbf. On the moon 1 lbm will weigh 0.166 lbf due to the pull of gravity being less.
I just like that method as it allows a bigger adjuster that is less likely to stop working. Especially if you antiseize the adjuster bolt. A 3/4" nut will fit inside of 2" square tubing with a 3/16 wall thickness with a bit of grinding.