Potentiometer knob collet work??

I have a 6.35mm smooth shaft Potentiometer and looking for a knob to go onto it. I've seen the set/grub screw type, i get how they work but worried about slipping.

Also seen the collet type but not to sure how they clench down on the shaft. The shaft isn't threaded, as just a groove running along the top of it. Would it work like a conventional collet from say a dremmel tool?   

Downunder35m4 months ago

Slipping????
Are you turning the potentiometer or are you trying to turn the entire device with the knob?