Blue Mountains Australia Foil Build

Its official, I am building
Started 14-05-18


Because that is your first one off the lathe, Its probably a bit off. You better send that one over to me in NZ. :grinning:


@michion Yes first one is a “little off” , In many ways. ( It will get better)
I would be embarrassed to pass on such shoddy work .
But in the future I am happy to trade, parts.
@rogjalon has me covered for 3D printing & he will be getting the next aluminium part I make.
I will trade metal custom parts for…Foil parts or huge amounts of cash $$$$$ :slight_smile:


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I started this project with a huge amount of cash. It disappeared pretty quickly.
I have a little hobby lathe. I should probably learn to use it.
I also rely on someone else for my prints, Shapeways. 3D printing looks like a pretty big hobby on its own.
Best of luck with the build.

It is a mix between pieces in aluminium and Pla. The sealmount has been modified with 2 bearings.


@michion Yes the cash can evaporate very quickly.
Happy to help you if you need advice with using your Lathe. But… I am also am returning to machining after many years. I will help you if I can. I know you were joking when you said “You better send that one over to me in NZ.” but maybe can find a way to share skills & or resources?. I also have sunk heaps of $ into just getting the hobby lathe & indexing head etc.

Perhaps I could send you a semi machined part with indexed holes? for you to finish yourself. ??

@cristophe Amazing work, you have done, I am impressed ! You have a couple of features I will incorporate in my next build. Thanks for the impressive design & images any chance of a cross section Assembly view?


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I’m glad I got in early with the trade, as this efoil building hobby already ate my huge amounts of cash🤑

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Update ,
Just another SLOW BUILD,
But I did manage to find some time today.

Just wish I could find the one missing bearing roller & the Neugart gearbox rebuild would be done. Currently thinking I will have to grind down an after market hardened pin & see how long it all lasts.


I think if you made an aftermarket one, it would be fine. There are so many of them. I think I counted 14 per planet gear.

This lathe stuff sure does eat up a fair bit of time! Nearly there.


@michion Your parts look very nice !

  1. Are you using the extra O-rings as water proofing or vibration dampening or something else?
  2. What Rz surface finish are you running on your prop shaft?
  3. Are you using a Lip seal or mechanical seal ? I couldn’t make it out in the photo.

Again very nice work you have done

The o rings down the back are for waterproofing. The others are to help centralise the unit and hold in the thermal grease that will be between the motor/gearbox and tube.

I had to google RZ finishes. I had no idea what it meant. I just went through the grades to 1200 with wet and dry, and finished by polishing it. It should be ok on the seals.

On my photo there are 2 brown Viton lip seals either side of a bearing. I was going to use mechanical seals, but I dont quite trust them enough in salt water. Or me to install them properly without contaminating them. I went for Viton over NBR seals because im not sure how hot this gearbox is going to get. NBR would probably be fine.

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@michion I like the way you are using the “extra” o rings very practical.
I had not considered Viton seals myself, guess I will now have to google them & see what is available.


Update only.
I made one new part made today .

So many things yet to make. However getting closer :wink:
So much fun!


Looking good Alex! Great work.

Made the missing link today. Now I need to design the other end.
I will be reading lots & looking for inspiration from all of you.


I managed to adapt MaB’s prop and duct design to make a bit of a hybrid aluminium/nylon assembly which isnt too dissimilar to yours. I managed to keep the plastic thread on MaBs design so I can still unscrew the duct. I think MaB’s design or Pacificmiesters design would work well for your motor/gearbox combo.


Very nice work ! @michion,

Vers Gréât job @michion

Just a small update with a huge thank you to @rogjalon for the 3D printing.


Just a update. I made this 8mm prop shaft tonight, this one was just practice in thread cutting & cross drilling stainless steel.
Now thinking I will use a 10mm shaft for the seals & bearings & turn down to 8mm at the back so I don’t damage the seals on assembly.