I have a carbon fiber end pin with a set screw that goes into it, to hold it in position. It does leave a kind of indentation in the carbon fiber. But so far, it hasn't damaged the endpin and I've used it for a lot of gigs since I bought it on December 31, 2016.
One thing I've been meaning to tell TalkBass is that I wanted to make the bass stand at exactly the same height every time I set it up. And stay there too. In the beginning, the set screw that holds the end pin in place would slip and the bass would get lower and lower and lower as I performed.
To this end, I put a shaft collar around the endpin at the position the end pin should be for the correct playing height. The shaft collar acts as a "depth stop" when it hits the female receptacle for the endpin on the bass itself. The shaft collar is atttached "semi permanently" to the endpin, meaning I never change the position of the shaft collar, ever, even though it is adjustable if I want it to be. And its never slipped (knock wood).
Here is what the shaft collar looks like. It doesn't appear to damage the end pin either.
https://www.amazon.com/gp/product/B000P0S32W/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
The shaft collar/depth stop uses a set screw to hold it in position on the end pin. This shaft collar has stayed in position, without any apparent damage to the endpin, for at least six months now. This also takes pressure off the set screw that attaches the endpin to the bass because the shaft color handles all the downard presssure on the end pin, and the set screw from the bass itself only keeps the end pin from falling out when I lift up the bass. No more end pin slipping!
It means I have to stow my end pin in my bow sleeve in my upright bass case during transport. This is because the depth stop, in doing its job, won't recede into the body of the bass during transport. But that is fine since at this time, I still don't bow much (the next frontier).
