Glad it worked out. I had exactly the same experience.
Mine also cracked with polycarbonate. I lost two of the three aluminium props. The weak spot is the relatively thin wall where the screw goes in. I’ve just printed a set with PET-CF to try and will then try PPA-CF. Ultimately though, I think we need to redesign the hub to have a slightly thicker wall where the screw goes in. I just haven’t had the time.
Agree it needs thicker walls, I have a friend who is going to redesign the hub as he is also using it for foil assist and has better CAD skills than me. He did solve it in the short term though by melting a staple into the weak area 
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would you be able to send me the files for these props ?
A simple fix is to do it like Mantafoils and have it split at the base and screw on the three (now). failing pieces to the base.
That way you could print it in the right direction and there would be no more problems.
On the other hand, I have not had any failing.
Printed in PC with no cooling.
Any addition of CF will only weaken layer adhesion and make the problem worse.
I first moved from 2 blades to 3 blades fixed aluminium Volker prop and then moved to FD clones prop which are the best for sure in term of behaviour.
I have no printer at home so always MJF PA12 for hubs. Never had any issue.
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Hi Eienne, where to buy or to build your FD clones prop ? Thanks
What orientation have you printed yours? I’m wondering if that is my problem. I just printed mine straight up from base to top. This means each line of filament is horizontal. Maybe I should add some angle. Let us know if you did anything different?
The same. Doubt printing at an angle would help much and at least with my printer I would definitely introduce some imbalance.
I only got a STL file. With a proper STEP or something it would be easy to fix.
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Thanks. I was using PC with 6 walls and 100% infill with a 0.6mm nozzle. Surprised mine failed but yours is fine so hoped it might just be a difference in printing. I’ve made some crude changes to the stl to thicken the weak spot so will give it another go.
I finaly got to test this once inhad first designed perfect cavitation free motor mounts and counter rotating props that work…
can confirm the 'inwards ’ or the outwards orientation does not make any difference to the boards steering or direct line of travel once cavitation issues are solved