To make it even easier .... I noticed this in my tool box (old Arrow Shark shaft saver - alum )
cgi.ebay.ca/Arrow-Shark-Shaft-...=item518f747055
Already has one 1/4" center hole and a M4 side bolt/screw - mine's a used 1
opened it up (slowly ...) 1/4" to 5/16"
[img]
u could open up with files or hand grinder too ......
http://www.modelgasboats.com/media/kunena/attachments/legacy/images/DSC04151.JPG[/img]
to keep this simple I retaped (cleaned threads) hole to M4 and used a short M4 fitting - I taped 5/16" tubing with M4 too so fitting screws thru (need to deburr inside tube
no allen set screw on this one
I polished it and left one side Red so u could see the Arrow Shark one
simple and clean (I think...........
later
Oh and I use Red loctite on the fittings and set screw ( a touch of heat to take them off ..) and they seem to stay well
Now I just need some of Scott's cool ball valves and small tank ... ...
I use this type Pro Boat greaser with diff grease