Set screw fell out from the trolley on the arm

The silver set screws were loose and one fell out today while cutting. Do they simply prevent the black Allen screws from turning? The other bottom one was loose. I tightened them up tight. Is that all they do? Picture is of the same set screws that are on the back side of the trolley

Yes those set screws are used for preloading initially. Not much preload gets applied to those bearings so a little bit of vibration may have caused them to work there way out. A little loctite should help prevent it in the future.

So… Should I not have tightened them tight then?

It’s possible that overtightening the set screws can throw the torch out of alignment. It’s an easy thing to check for and correct. Part way through this thread I explained how to do it: Torch square to table adjustments

What about the set screws on the other plate the torch holder is on? The ones that are vertically oriented & fall straight down?

Those are the ones I had problems with but I could only get a picture of these

mine were also loose. i was surprised that locktite was not used from factory on really anything that was suposedly ‘preset’ considering the vibration and movement.