I rebuilt the whole motor pod with new Neugart gearbox, 4:1 reduction ratio so I use a little smaller prop (146mm) with 236mm pitch. It work just fine, really fast, feels more “direct” on the throttle probably because of less reduction ratio (former Apex gearbox was 5:1).
Current draining is still acceptable, few amps less than before because of the thrust bearing now getting the load from prop, which seems the reason for which Apex died.
Give it a try, keep an eye on ammeter to be sure. My setup has an electronic antispark switch, very handy, with 90A Maxi-LAMA fuse and it still intact so… Absorption is the last of my worries now, problem is still water leakage of ESC box, which I should open and dry after any run…and not straight prop shaft!
Is there a link to the STL of the 236 prop somewhere on the forum? Ill still try the 305 because Ive already printed one. Looks really good too!
My antispark and circuit breaker are manual for now, to keep it simple for me. I might learn about the electronic relay stuff later on.
Not yet, I’m moving and still not having internet access with my computer on new home. As soon as possible I upload it. But for 5:1 that prop is just fine!
Hi MaB,
I’m keen to print your prop as well to compare it with other props. I already started a sheet with foiling velocity (at fixed speeds of 20, 25, 30 km/h) vs. power consumption. I will collect some more data and will post my results soon.
My setup is SSS 56104 700kv / Neugart PLE40 8:1 . Can you suggest a size for the prop and upload a Solid Works file? This would be really nice of you.
Cheers mate
Sorry for not having answered yet, I moved to another town and still haven’t found an order on all my stuff yet! Will do.
At the end, I got a mini lathe, one of those chinese model rebranded all over the globe. Used, super cheap, more than ok to work any kind of metal up to stainless steel 316, steel needs lots of care and patience but it’s doable. This new shaft is made in Ergal, aluminum 7075, still have to try it because I replaced the mast wires and have to redo all the soldering to new ESC also but I guess i will keep up.
I’m working at a full metal tube end, to get a more reliabe and precise part.
I did the broaching for the keyway on the mini lathe as well, grinding a special tool in HSS.
Do you think Ali will be strong enough
I wish so! 7075 is used on motorbike components as well… it’s stronger than other types of aluminum. I’m working at the plan B: stainless steel, just in case
I managed to lathe mine in stainless on the smallest optimum lathe available. Im sure you can do it too. Then you dont have to worry about corrosion issues or wear on the alloy shaft from seals etc. I used carbide ISO inserts on a 8mm bit holder and a small milling attachment to plunge a 3mm end mill for the keyway.
Cool!! My lathe is the same size as the mini Optimum. Ain’t that bad, with average quality indexable carbide inserts, plenty of patience and time, eats up steel quite nicely. Talking of 20/25 millimeter rods, because for the tube cap, 61mm max diameter, I’d to go with aluminum or the lathe would die!
What kind of insert have you used for the keyway on steel? I’m afraid HSS shaped bar might not be up to that…
I cut the key way a bit differently. I plunged a 3mm HSS end mill bit into the blind hole. It leaves a half round looking key way, but it still works.
If you have already made the tool for cutting the key way in HSS, I think its definitely worth a go. You might be surprised. Take real shallow cuts and take your time. Let us know how you get on.
Hi MaB
Would you mind suggesting a prop size for a SSS 56104 500kv / Neugart PLE40 5:1 setup and maybe upload a step/solidworks file? Maybe you already have this in CAD, since it is standard pacificmeister setup?
This would be very kind of you!
Cheers
The optimum prop size is between 135mm - 140mm diameter. Then basically just vary the pitch to maximise potential of the motor and gear combination.
I used 360KV, 5:1 with 148/300mm pitch and 360KV 4:1 142/215mm pitch (maybe 200mm pitch would be enough).
I shared my design already, on propeller topic… SW file and stp print ready. My prop are not based on Pacificmeister design, I did it with Javaprop and Solid works.
I’m dragging my feet lately, for what concern new Efoil, but it still there, almost. I had a crush with metal machining this winter and I’m trying to recovery from the toolmaking disease, “need to build another tool for the lathe, to build one more tool for the milling machine because I can’t live with the thought that it would be fundamental in building something next year… something undefined but likely another tool”…it seems a common problem of home shop wannabe machinists, apparently. 
Hi @MaB
Thank you very much for your reply. I found your 142/215, and will start with this for my 500kv, 5:1. What material did you print your propellers in? Im thinking either ASA, with acetoned surface, PLA with epoxy surface or maybe a Taulmann 910 Alloy, with epoxy surface.
I used Polycarbonate (PCmax), stiff and very strong. I just designed and printed one in PLA also, for a mate who lives nearby and he’s finishing a new efoil, PLA is ok.
Despite I love ASA for many application, I found it too flexible and with not enough strength, for our propellers. PETG is strong enough but too flexible to grant performances.
I suggest to finish the prop with epoxy, a couple of layers better, and then sandpaper.