Hub for a 3 blade FoilDrive blade

A hub i designed for a 3 blade foil drive blade. Should fit the original FD blade. Havent tested it yet.

Its suppose to use m4 screws and self locking nuts,

i used these screws for dimensions 

New version: i removed the negativ step 

https://www.eisenwaren2000.de/Zylinderschrauben-M4-X-12-mit-Innensechskant-niedr-Kopf-DIN-7984-Edelstahl-A2