Questions BlueROV2 frame


I had a question regarding the BlueROV2 frame. When do you guys use a 5.2 mm or 5.5 mm hole? Because when I opened the frame in Autodesk Inventor, it says that the same bolt is used for the 5.2 and 5.5 mm hole (see pictures below). Also are all the holes in the frame threaded or how do you guys connect all the parts together with the bolts? Thanks in advance.

Schermafbeelding 2024-03-18 114305

Hi @MartinFaak -
The 5.5mm hole allows room for the M5 bolt to reach the square nut in the frame piece, this provides a bolted connection.
The 5.2mm hole provides a tighter fit, but still clearence, for a bolt that goes through it and threads into a metal 90 degree bracket.
You can see these connections in the assembly guide.
The 5.2mm holes are used with the Heavy upgrade kit, you can see how in this guide.