I have a Spots 2 Freerace front wing that came (damaged) with a Spotz 2 Foil Board running a 'slalom front wing' - and yes I bought it blindly intending to learn on it - well that bubble has well and truely burst! From what Im reading I might have half a chance if I can get the Freerace wing up and running - only the spigot that connects the wing to the mast had rotational movement as well as some sideways deflection (photo 1) where it connects to the front wing.
In other posts on SB I had asked about repair otions which Id exhausted (up unitl Id already drilled some holes - thanks Marvin) so had a crack myself and Im interested in the engineers views !
I got hold of some 3mm stainless threaded rod and have carefull diagonally drilled through the spigot into the front wing and have injected epoxy resin into the 'loose' area trying to resaturate that area and then inserted the 3 threaded rods - photos 2 and 3.
My research suggests each of the 'rods has a tensile strength of around 60kg / mm2 and the shear strength is about half of that = 30 kg/mm 2. Given a 3 mm threaded rod is really only about 2 mm of solid dia Ive calculated the shear stress load per pin with a radius of 1mm = 3.14 mm2 x 30kg /mm2 = around 90 kg - is that correct?
With 3 pins solidly expoxyed in on the diagonal can I assume a shear load of 3 x 90 kg = 270 kg ? Im also hoping Ive minimised the torsional movement ? To date I have trimmed the pins and carefull trimmed the spigot to closely fit the mast and it seems to be a solid and tight fit with very little movement.
I havent load tested it yet but do my maths stand up to scrutiny ?? Am I dreaming that I might have fixed this freerace front wing's 'loose spigot '???
Lambie
> 9 months ago, 11 Dec 2017
