I keep seeing folk say these are not decent units and only suitable for hobby use but thats not been my experience.   Sure they are not the last word in precision engineering but are more than capable of doing a pro job of sharpening chains presuming they are all of similar quality to mine. The main pivot is good quality with minimum play if any. The chain support is rudimentary but adjustable and consistent. The weakest part is the chain stop as its a bit flexible. They way to work ar