I've long wanted rimless specs even though they are expensive. My eyes have now 'reversed' - I no longer need specs for distance but I need them for reading. Specsavers told me that rimless would not be strong enough for reading specs as I would be taking them on and off all the time.
I've got two pairs of rimless varifocals, had them (first pair) for 6 years no problem. But they are very expensive ones so they damn well should be ok!
I would rather not have to wear specs, but can't get on with contact lenses. I'd thought about perhaps having rimless ones the next time, but when I suggested it at my last test, the assistant did say they were liable to cracking at the area where the screws are. I just thought they would perhaps look a bit nicer as they might not show up as much on my face!
Mine were fine and I loved them but they got rather expensive when it came to getting new ones. I think the current fad for hard edged specs is very ageing.
I've had a pair some years ago and they never gave me any problem. I was still working at the time and wore them all day. Really light and comfortable. At that time my daughter worked for Specsavers. She told me they had to treat lenses in rimless glasses carefully when adjusting them in case they split. Maybe the screws in yours are faulty.