Using a plastic nut is this clamps downfall.
Like several others have stated, if you use the sharpener with any frequency, you'll strip the tightening nut as it's made out of VERY soft plastic. It's actually two pieces: the inner threaded sleeve and the outer "star"/grip and they are epoxied together. This is a major wtf design decision that really shows it was designed to fail.
The tightening apparatus is MIM cast and the reverse thread has two flats on it - this makes it wear the nut even quicker. Once there is some actual tension and you are tightening it down, it's literally cutting a bit of the thread away in the plastic (you can see this in the pics I've posted).
Really awful design decisions that weren't made for longevity and were obviously made to cut cost and force re buying this assembly.
Even if the nut was also MIM cast it would greatly improve function and would be inexpensive to produce. That way it's at least a metal to metal interface.
Deciding to MIM a single piece pushing block and threaded post with two flat sides that interfaces with a soft plastic is one of the more bizarre product engineering decisions I've ever seen.
The fact that the thread post has a 90° angle with the push block is also telling that this wasn't engineered correctly - it creates a stress riser and will fail the second any lateral load is placed. It needs a mild fillet/radius, which is incredible nobody saw the error prior to production. This is mechanical engineering 101 stuff.
While more unlikely in a fixed…
