Hi All,
You will never guess what there are. My son asked me to make 50 following a trial of 10 made recently.
Made in two parts and screwed together. I didn't have a suitable 5C Collet for the 3/8” square part so I made a round collet that was a slip fit across the corners of the square bar and them cross drilled and tapped it M6.
Both parts made in my cnc lathe. Threading was done manually. Material is aluminium which I chromate converted at the end.
I am not 100% sure how they are used myself.
Chrisjh