Technical, Techniques, Hints, and Tips > Engineering Techniques and Materials.

Grease or Oil? & setup of Prop Shaft

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tizdaz:
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:
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.

tizdaz:
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:
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

tizdaz:
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 :) ?

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