If anyone is going to repeat my experience, I want to give one piece of advice: be sure to use thread locker or locking nuts in all screw connections. I almost lost the gearbox. I noticed that all the screws had come loose except one. And yet I lost the propeller. Then I printed the propeller on a 3D printer. I made it with splines in the hub, and no longer used an adapter, but mounted it directly onto the output shaft of the gearbox. But it seemed to me that with the printed prop the thrust decreased a little.
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I designed a planetary gearbox for the 65162 motor with 65 mm diameter.
Ratio 2,87 to 1
The spurgear works fine since 15 hours and the angled gear ( 20 degrees) needs some improvement as it failed after 1 hour
Also tested with 75165 motor and 14 NM of torque
All parts 3 D printed
Prop 3 D printed 215 mm dia and pitch 3D printed
Thrust is so much more powerful
Ich will publish final design when ready
Cost with all Bearings, Screws and Print Material approx 50 Euro, however if the bearings should be saltwater proof you need stainless steel and you will reach easily 100 Euro.
The gear runs wet in water that it is cooled …
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Why are you making gearboxes for these motors? These motors were specially designed for direct drive of the propeller. Are you claiming to get more thrust? Wouldn’t it be better to develop optimal propellers for these motors? I’m afraid that the plastic printed gears won’t last very long.
I was even surprised that your plastic gear lasts 15 hours. This is great.
I have a planetary gearbox made of steel. But I don’t know yet how to secure the sun gear to the motor shaft. Because my sun gear has splines, and the motor has a D-shaft. I also thought about printing a gear, but decided that it would not work for even a few minutes under load. Now you have given me some hope. I guess I’ll try. True, my motor speed is about 4 times higher than yours, but yours has much more torque.
What kind of plastic did you print the gears from?
I guess I understood your idea. Motor can produce more power at higher RPM. With the help of a gearbox you reduce the RPM, and now you can use a large propeller, which is more efficient.
Good morning
the explanation why to do this is the following:
To get maximum thrust at given speed of the board the optimum prop has max diameter and min volume flow at this speed.
Same as designing a prop for a plane to get best performance in aviation.
Thrust is a function of volume speed of the fluid and the energy needed is a function of volume speed squared.
Thats why jet drives are a bad idea for efoils and not so efficient
I needed 1,4 KW to foil now I need less than 1 KW
All parts are special PLA.
The spur gears have no wear so far
The prop is very strong as it has a bigger thickness of the profile due to its diameter
Disadvantage is the hearable noise of the gears . Spur gears are hearable for others the helical gears are almost not noticeable
Hope this helps
R
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Good morning.
Thank you.
It’s amazing that you were able to create a printed gearbox.
What if you use a smaller motor? Is it possible to make a two-stage gearbox? Since 1 kW is enough for you, you can take a much smaller motor and much cheaper. However, it is difficult to find a waterproof one.
Did you measure the torque on the motor shaft or on the output shaft of the gearbox? Or do you use motor specifications or calculated data?
I’m currently working on building my own motor and looking for a way to measure torque.
What limits the maximum diameter of the propeller and the maximum pitch?
Where can I read this information?
I did my assembly without a scientific approach, based on the experience of the participants in this forum.
This is a very clever design. Great for DIY on a budget.
There are so many factors that can skew a comparison like this. Is it with everything except the prop and gearbox the same (foil, board, weight, pitch, speed etc)?
Which was the prop that you tried in direct drive?
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I have ordered the metr equipment bit not yet installed.
The data I got with the VX3 remote and I agree that its a little bit vague
Just what I had at that time
In my case bigger would have contacted the fuselage
My assumptions to do that are the following:
The motor runs best and most powerful at approx 2/3 of idle speed so approx 5500 UpM
The ratio with a 3D printed design with max planers was approx 3
There is a prop generator on the internet where you can rype your values and it proposes you a design
This is how I came across wirh my concept
But:
Direct drive also works fine I just had fun and was super amazed that it can be printed.
I thought the geards would explode by the first turns
Here are some pictures of my powerplant.
Motor after use. It looks like only the front cover screws are a little rusty. The motor works, I didn’t disassemble it.
The front motor support, which also serves as a transition from the motor housing to the gearbox housing. Rubber ring installed.
Rear motor mount. There are power cables running through her leg. The wires go into the fuselage, then into the mast. The fuselage is made of rectangular aluminum tube. I didn’t have to make any extra holes in the mast. Rubber ring installed.
Gearbox from the inside.
Gearbox and 3d printed prop.
Gearbox on the motor side with a coupling screwed onto the shaft for connection to the motor shaft. Instead of a clutch there was a clutch cup for connection to the trimmer motor. I put this cup away.
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I had a plastic prop from China that I cut to 5 1/2 diameter
Theoretically it should be not a good design but I spent on day in the pool measuring theust via power etc.
This was the best and better than 2 cnc props I specifically bought for efoils
And:
If you design a specific motor gear prop unit you must determine what you want.
Max speed, max efficiency, best performance at given speed etc
Its like the gears from a car. First gear is good power to start but low speed , 5 th maybe too weak to start
I designed for 25 kmh speed and best efficiency as I dont like to fall down at 40 kmh
I reach max 35 kmh with this setup its just more efficient than my old direct drive
Hi Vladimir:
Trying to answer your questions:
Smaller motor:
A foil drive system is in principle like a airplane.
At takeoff you need
Accelerate the plane
Climb
Growing air resistance
Thats why a plane has engines that are 4-5 times more powerful than in levelled flight at ( low density high flight levels)
I do not recommended very small motors as they will take looong time to get you out of the water
I needed one day to find a prop in direct drine to take me fast out of the water ( approx 145 kg total wheight with a 2500 cm2 fanatic wing)
I used the motor data in the diagramms and the 75165 produces approx 14 Nm of Torque.
This motor was only for testing the gearbox as it produced almost 14 kW
So approx 40 NM will be on the prop shaft
The remote gives you RPM and Voltage and Amps which is power.
Power devided by RPM will give you torque.
It will have much less than 10% failure in it
Or you hold the motor and try to measure the static torque to hold it ( with a lever and a scale) somehow
Zero failure
Will copy the internet prop generator if I find it here
Have Fun
Robert
It would be interesting to see how this runs on one of the 56115 inrunners.
Last year i made an electric surfboard. I used a 4092 motor, a 6c battery, gearbox for a bicycle, same as in my current project, a 2:1 belt drive from the motor to the gearbox, and a 7 1/4 * 5" propeller. Total ratio 9:1. I got such a big thrust that I first I couldn’t stay on the board, lying on it, it pulled forward from under me. This is about the question of how small a motor can be installed. My weight is 70 kg, the weight of the board then turned out to be about 15 or 20 kg. motor, belt and gearbox stood inside the board.
Hi Vladimir,
congratulations to the printed parts I looked at the fotos I always failed to make it waterproof.
This is the prop program on the internet
I am 105 kg so I need a different motor.
9:1 is like first gear in a car if you can reach foiling speed its fine
In the forums they talk about 2 kw max power to start to fly that could be right somehow
And the less drag the underwater foil parts have the much better
I tried a prop ring around a direct drive 65161 and I failed to foil, so drag is even more important than a little bit more power.
Eflite says the ring causes 40% more drag and it is pretty. nice design some might think
I also looked on internet for ready to use gearboxes but did not find except a 500 USD Version
This is the prop link ( it did not copy it in before)