Waterproof shaft


#1

Hi. Thinking about how to get the shaft completely waterproof. Have looked at common ball bearings from NTN and SKF with seals, but these are certainly no ip-class. Anybody have experience with this?
/Christian


#2

You mean something like 608 2RS bearings with double sided rubber seals and grease inside? I have those for testing with a direct drive outrunner setup. Do you have a rating considering differntial pressure for those? I did not find a pressure spec, I just use them to protect the bearings in water.


#3

I mean to protect the bearing that is attached to the housing (have not found any waterproof bearings yet).I think I will make some tests with:
https://m.grainger.com/mobile/category/rotary-shaft-seals/bearings/power-transmission/ecatalog/N-kz2Z1z0nx9h

A rotary shaft seal (or maybe multiple) attached on top of the bearing that protects from water


#4

I guess most people here have to deal with the danger of getting saltwater into the motor/bearings…


#5

Two oil lip seals to seal the shaft and I am also using a ceramic bearing running wet outside of the seals to stabilize the prop. See: Pacificmeister Build Info and CAD Sources


Self introduction and Jet Pump Shaft Seal! :)
#6

Do you have a complete waterproof housing? Any problem with leaks with that solution ?


#7

Another variant could be to use a rubber tube with the same inner diameter as the shaft and put fat on the inside. The advantage of this is that the contact surface between the shaft and the seal becomes considerably larger, however, one should look at heat generation.


#8

Hi @pacificmeister will a mechanical seal work ? or did you find “Two oil lip seals to seal” better ? is RPM a issue?
SEAL
This is what I was thinking, not as elegant as your amazing design.


Its a WIP.
Many thanks to you & everyone on EHB.

Cheers,
Al


#9

Would be interesting to hear how it works. I haven’t tried. We discussed it here: Pacificmeister Build Info and CAD Sources


#10

Thanks i had not seen that discussion a few good points were raised.
I will consider all points. I will share the results.


#11

Hi All,
About two weeks ago I purchased a 500KV SSS then after many hours of hunting found & purchased a used Neugart 4:1.
So not the optimum ratio for the 500KV SSS. I consider I have two options buy a 360KV or drop the voltage but increase the current. Can anyone advise as too the best way to progress. ?
Many Thanls,
Al


#12

Keep voltage at 12S, keep 500KV and keep 4:1 gear.

Having a slightly reduced gear ratio wont make a huge difference. I ran tests with 8S, 10S and 12S with a completely different setup (750KV and 7:1 gear) to what you have and found the following:

  • 12S will reduce the current needed at low RPM to achieve the same power before you get onto the foil.
  • Even though 12S means you should theoretically have a higher RPM at the prop, because of losses you’ll see something different.
  • At 12S you wont need to necessarily drive the motor at full RPM to get to top speed.

#13

Thank you Jezza, Great advice !


#14

Think so far the most suitable solution is lip seals. Maybe multiple of them.
What brand of lip seals are you using today?


#15

I assume so too. But if someone has tried the mechanical seals, I would love to hear how it works. I am using 2 lip seals from McMaster.


#16

Have you guys thought about using electrical gel or magic gel in your motor tubes or filling your ESC compartment with it to work as a waterproof and more so cooling strategy? It looks interesting. https://www.cef.co.uk/catalogue/products/1050077-2-x-0-5ltr-bottles-of-magic-gel-mixing-jug


#17

I use it for my esc box, it’s just a little messy to remove