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@Batman
after multiple messages back and forth with the ebay seller to make sure the crank was exactly what i wanted i got this.
every cloud has an aluminum lining so I decided to use my mates big brain (and his cnc machine) to mill a new one.
Fusion 360 has just come out with generative design which takes force input and then uses an algorithim to find the optimum amount of material to perform the task. This is obviously massively simplified but it's worth a google.
Enjoy the following image dump.
6061
early iteration
I was a little bit worried because the later iterations seemed to be held together with aluminum toothpicks and faith. But this one seemed viable
All toolpaths
rearside complete
and it fits! Pretty pleased as I modelled the spline with a pair or calipers and a lot of assumptions
And the front. We added 2mm material overall to be on the safe side as i needed it asap. Lime bikes were putting me in debt.
in all honesty a bit of fettling was required as i had modelled the angle of the crank from the face incorrectly, nobody's perfect.
cut the tabs and filed.
Tada. Unfortunately it looks a lot better from the back since much more material is removed as it flares towards the spline profile. All you need is good ideas, better machines, and sick mates. Get to it!
Excuse the shite editing, I'm lazy! will put future skill points into patience and photography.