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Author Topic: Grease or Oil? & setup of Prop Shaft  (Read 1860 times)

tizdaz

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Grease or Oil? & setup of Prop Shaft
« on: December 24, 2017, 01:16:08 AM »

Hi guys


I have a 30cm long (8mm inner) prop shaft, i'm using a 5" 4 blade prop with a 24v motor, rpm is roughly 3-4k, i bought the shaft from MMM & opted for the oiler tube fitted to make oiling/greasing easier.. But i'm not sure on is a couple of things..


is it best to use grease for the shaft or oil? my coupling is BELOW water line so will need to stop water coming up the shaft.


Also, as its a brand new shaft, i've read that it will need running in, whats the procedure for doing this please?


Also my prop shaft has a nut & washer for either end, the way i have set it up is ive tightened the nut against the prop & the washer sits in between the nut & the shaft & on the other end the nut is tightened against the coupling & the washer sits in between the nut & shaft.. is this right? if so then is there really any need for the washer as its loose (just enough gap so the shaft rotates) ?


Thanks guys


Daz

grendel

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #1 on: December 24, 2017, 05:49:56 AM »

I had issues when I greased my prop shaft, it dropped the revs I was able to get by several thousand rpm  (though in the end I ended up putting a bigger lower revving motor in) I dont have an oiler, I just put a drip of oil at each end by the washer.
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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #2 on: December 24, 2017, 06:44:09 AM »

hey, yeh i've read about grease putting more strain on motor, but i don't want any water to come through tube & grease is better to stop water coming through tube? Or will oil do just as good of a job, what oil is best to use?

roycv

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #3 on: December 24, 2017, 09:15:13 AM »

Hi I have posted this several times and I have been doing this since I don't know when.  I think this mix comes from Deans and it works.
 Mix 1 part WD40, 1 part Vaseline, 1 part 3 in one or similar oil in a small container.  Mix it up until it is a little stiff.

 I slide a piece of plastic tube onto the motor end to cover the prop tube, take the shaft out, and with the prop end of the tube in the mix suck the mixture into the tube.  You only need to half fill the prop tube
 Disconnect plastic flexible tubing and then gently slide the prop shaft into place and this will distribute the rest of the mixture, be ready to collect the residue coming out of the motor end of the tube and re-use for next time.

You could also use a plastic hyperdermic syringe to inject the mix direct, I have also sucked the mix into a short length of clear flexible tubing placed over the end of the proptube and used the prop shaft to move the mix into the tube.
This will stop water coming in and is almost frictionless. 
regards Roy
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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #4 on: December 24, 2017, 09:33:38 AM »

hiya


sounds a great idea but i'm a little confused on your method about sliding the tube over the motor end etc (it's just me being a little blonde as they say!) can you explain a little more please :) ?

roycv

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #5 on: December 24, 2017, 09:38:54 AM »

Hi, I fit the tube so I can suck the oil mix into the tube. If I suck too hard, not likely these days,  I can see the mix coming up the plastic tube and stop.  Its not going to kill you but WD40 does last a long while in the mouth!
I suppose you could jam a syringe in the end and use that to suck the mix into the tube.
regards Roy
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T33cno

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #6 on: December 24, 2017, 09:48:51 AM »

Hi guys


I have a 30cm long (8mm inner) prop shaft, i'm using a 5" 4 blade prop with a 24v motor, rpm is roughly 3-4k, i bought the shaft from MMM & opted for the oiler tube fitted to make oiling/greasing easier.. But i'm not sure on is a couple of things..


is it best to use grease for the shaft or oil? my coupling is BELOW water line so will need to stop water coming up the shaft.


Also, as its a brand new shaft, i've read that it will need running in, whats the procedure for doing this please?


Also my prop shaft has a nut & washer for either end, the way i have set it up is ive tightened the nut against the prop & the washer sits in between the nut & the shaft & on the other end the nut is tightened against the coupling & the washer sits in between the nut & shaft.. is this right? if so then is there really any need for the washer as its loose (just enough gap so the shaft rotates) ?


Thanks guys


Daz


Hi Daz
I have the self same shafts and no I have no washer on the unthreaded exposed shaft.
I use 20/50 engine oil and water has never come in.
Also note I use superflex couplings from Steve @ model boat bits.


EDIT because the shaft is reduced to 5 or 6mm from 8mm at the prop end it is inserted from within the hull and stops against the bearing at that propeller end of the tube. Therefore all shaft float is controlled by the nut and washer there.


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Peter Fitness

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #7 on: December 24, 2017, 08:32:14 PM »

This subject has been discussed many times, and there are two trains of thought. Many very experienced builders claim, no doubt with justification, that grease in the prop shaft slows the motor down and adds to current drain. This has been proved by some using a multi meter and I certainly donít dispute it. Personally, I pack my prop shafts with marine grease and am still able to get between one and two hours running time out of my 6v, 4ah SLA batteries, more than enough for my purposes so, for me, any drag induced by the grease is not an issue. The grease definitely does prevent any water ingress via the prop tube. I believe that it is up to the individual to make his own decision based on his own requirements.


Peter.
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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #8 on: December 24, 2017, 10:24:44 PM »

Thanks for info guys

i've done away with the washer motor end as T33cno suggested but will keep the one on the prop end and use it in between the nut & prop as it seems pointless to place it in between the propshaft nut & propshaft as there is no contact in between these points.

My batterys i'm using are 12v 22ah (i'm running 4 of these in series/parallel setup to give total output of 24v/44ah), so think im going to go down the grease route, so on that note, anyone recommend a certain grease? Theres this one in euro car parts whcih is only around corner from me but will it be ideal? : https://www.eurocarparts.com/ecp/p/car-accessories/car-maintenance-accessories/maintenance-fluids-and-greases/grease/?526770280&&cc5_150


Thanks guys :)


..ah almost forgot to ask, with it being a brand new propshaft (which has an oiler attached) should i just use a syringe & put the grease down the oiler with motor running, or should i remove inner shaft & coat it with grease then place back inside shaft (removing any excess that pops out other end!) as at the moment it's bare with no lube at all?

T33cno

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #9 on: December 24, 2017, 10:29:29 PM »

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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #10 on: December 24, 2017, 10:34:42 PM »

ah you dont use a washer prop end either? i was thinking not to as im going to be using a threadlock anyway?

T33cno

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #11 on: December 24, 2017, 10:37:31 PM »

Yes there is very clearly a washer there
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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #12 on: December 24, 2017, 10:40:23 PM »

Yes there is very clearly a washer there


ah ok thought that might have been shaft end, but with the washer there, how tight is the nut against it? as ive been advised to have a tiny gap between the shaft & nut to allow a little play so shaft can run freely ?

T33cno

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #13 on: December 24, 2017, 10:43:17 PM »

No discernible gap
Should be just so there is no binding
The washer not only prevents the nut wearing against the end of the tube but provides a larger surface area    to slow the travel of oil
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T33cno

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #14 on: December 24, 2017, 10:54:41 PM »

A point to note
MMMís advice for their shafts is to use thick engine oil
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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #15 on: December 24, 2017, 10:58:24 PM »

No discernible gap
Should be just so there is no binding
The washer not only prevents the nut wearing against the end of the tube but provides a larger surface area    to slow the travel of oil


when i tighten my nut against the prop then it doesn't touch the shaft, with the washer not being tight, doesn't it make any noise with the vibrations or?

T33cno

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #16 on: December 24, 2017, 11:00:32 PM »

If there is surplus shaft so the prop wonít screw on far enough then the options are to tap the hole deeper in the prop or shorten the thread.
From memory I think I had to clean out the prop thread which wasnít tapped very cleanly and shorten my shafts
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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #17 on: December 24, 2017, 11:31:27 PM »

hiya, yeh i had to shorten the thread on mine when i first got it but fits perfect now, when i tighten the nut to the prop & on the other end i tighten the nut to the coupling then there is no play at all which is why i'm not sure if a washer is needed as it would basically be just hanging & not tight, sorry for all the "noob" questions but its first time i've don't a build (as you can probably tell!) thanks for all your help :)

T33cno

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #18 on: December 24, 2017, 11:36:22 PM »

The way I did it on my super smooth shafts was to put the washer on put the nut on and turn it all the way up hand tight. Then whilst holding the shaft at the other end screw the propeller all the way up to the nut.
Then holding the propeller secure turn the nut back tight against it. This relieves the pressure on the washer just enough and locks the prop.
I also used thread lock
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tizdaz

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Re: Grease or Oil? & setup of Prop Shaft
« Reply #19 on: December 24, 2017, 11:38:55 PM »

The way I did it on my super smooth shafts was to put the washer on put the nut on and turn it all the way up hand tight. Then whilst holding the shaft at the other end screw the propeller all the way up to the nut.
Then holding the propeller secure turn the nut back tight against it. This relieves the pressure on the washer just enough and locks the prop.
I also used thread lock


oki doke! ..thanks again been a great help, i'm getting there...sloooooowly! lol :)
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