prop making noise??

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10 November 2012 at 14:37 #37501
Jay
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@jay
hi i am building the billings boat Andre Gail i have just put all the elctronics in and the rudder and prop. i tested it all before hand and everything works great however the prop shaft is making so much noise and i do not have any more ideas on how to make it quiet. its an angled prop so had to build a base for the motor to sit on also at an angle, i have made sure that everything is aligned correctly but the prop shaft is still rubbing against the brass tube it fits in. the brass tube is firmly secured and doesnt move, i have used the suppiled bush's either end of the brass tube aswell but the noise is crazy…i have read a few forums and the idea of using grease or oil comes up alot but this still hasnt helped. is there anything i am doing wrong here? help wouold be greatly apprecieated as im new to all this many thanks

JAY
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10 November 2012 at 14:37 #2198
Jay
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@jay
10 November 2012 at 15:32 #37503
ashley needham
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@ashleyneedham69188
Jay. Are we talking about a plain tube in which the shaft runs in, or are we taliking about a tube with bearings in both ends that the shaft runs in?

If it is a plain tube, it WILL be noisy and thats that. If it has bearings, these might be a bit loose, either in the tube perhaps or they just have too much clearance for the shaft and so it wobbles.

It is worth checking that your shaft is dead straight and not bent, by rolling it on a flat surface.

Lastly, your prop may be out of balance. I have had two noisy boats, and they reduced to silence on changing the props..

Ashley
10 November 2012 at 17:39 #37506
Malcolm Frary
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@malcolmfrary95515
If the shaft is straight, hope that the tube is straight as well.

What noise are you getting? Scrape, knock, buzz?
10 November 2012 at 19:10 #37507
Jay
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@jay
Hi sorry in my original post I called them bush’s…yes I do have bearings they are defiantly tight in the brass tube I had to knock them in with a hammer and afterwards I rolled bothe the shaft and tube on a glass window and both seem straight to me. It’s a scraping noise Its seems to be grinding on the bearings but I’m at a whitsend at the moment I’ve re positioned the motor countless times and it still noisy just can’t understand it. The prop is the one supplied it’s plastic and doesn’t look good quality so maybe I could replace it however I’m 99% sure it’s the shaft grinding on the bearing is there anythih else I can do or would you sugest replacing the lot. Thanks for the help much appreciated
11 November 2012 at 09:02 #37510
ashley needham
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@ashleyneedham69188
Jay. If the thing is adjusted properly (absolutely minimum end play, and I have used nylon washers before now <make them out of plastic milk bottles with a punch>and using one either end, adjust for ZERO play)), the bearings have a lighs smear of grease on initial assembly, and the motor is NOT taking any end-thrust, after your checks there seems nothing much else to do other than replace the propshaft. Having first tried another prop, anything really, just to try.

Myself I lean to nylon bearings nowadays,water lubricated,cant go wrong, but everyone has their favourites.

Ashley
11 November 2012 at 09:24 #37512
shipwright
Participant
@shipwright
Hello Jay,

It would help the members of this forum who are trying to diagnose your model boat problem if you could post a photo or two of the running gear in your boat.

When you say "angled" is it one straight line from motor shaft through to propeller or is the motor shaft at a different angle relative to the propshaft? Is your motor connected to your propshaft via a universal coupling ?

Your description said that you had to insert the bearings into the proptube – how did you ensure that the axes of the bearings were perfectly aligned – ie how did you ensure that they are not "skewed"? All the propshafts/proptubes that I have used were completely assembled by the manufacturer.

Ian
11 November 2012 at 11:54 #37520
Malcolm Frary
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@malcolmfrary95515
With the motor not coupled, does the scraping sound still happen when the shaft is turned by hand? Does it only happen with the shaft pushed one way or the other? I usually try to arrange a couple of brass washers between the face of the prop boss and the tube end bearing to act as both lubricant retaineers and thrust washers. Others have spoken well of nylon washers, having the merit of being self lubricating in water.

If its just a rough bearing surface, be it end thrust or otherwise, an old trick was to do a "running in lube", using metal polish as the "lube" until it quietened, then cleaning away every last bit of polish before relubing. Knocking the bearings in with a hammer could have resulted in the bearings getting reshaped a bit.
11 November 2012 at 15:24 #37524
Dave_P
Participant
@dave_p
I am more than a little suspicious of the bearing alignment due to Jay's statement "I do have bearings they are defiantly tight in the brass tube I had to knock them in with a hammer"

That would be my first port of call.

Cheers

Dave
12 February 2013 at 21:39 #39178
Redbunny
Participant
@redbunny
Hi, Jay i have read your post and the replies but are you talking about the shaft being noisy out of the water or in it, most shafts are make a bit of a racket out of the water but shut up when put in the lake, i have found they can get quieter the more the boat is used {run in}.

A few drops of GT38 works wonders on anything a bit noisy you can get it at good bicycle shops its like WD on steroids.

Gordon { Redbunny}
13 February 2013 at 06:46 #39186
Redbunny
Participant
@redbunny
Posted by Redbunny on 12/02/2013 21:39:47:

Hi, Jay i have read your post and the replies but are you talking about the shaft being noisy out of the water or in it, most shafts are make a bit of a racket out of the water but shut up when put in the lake, i have found they can get quieter the more the boat is used {run in}.

A few drops of GT38 works wonders on anything a bit noisy you can get it at good bicycle shops its like WD on steroids.

Gordon { Redbunny} I meant GT85 ,also try repalcing the center part of your coupling with a solid piece of tube that will take the end bits, put it back together connect it to the motor and see if the shaft will screw back in if it wont your shaft or motor are not in line, this is a good way of making sure of perfect alingment before fitting the center part of the coupling
13 February 2013 at 09:15 #39187
ARTHUR COLLETT
Participant
@arthurcollett48040
Hi Jay.

What type of coupling do you use? Universal coupling or Dog Bone Type. Experienced in the dogbone type some binding due to the tight fit. Little misalignment causes a funny sound in the shaft.

Regards

Arthur
13 February 2013 at 21:13 #39209
captainslog
Participant
@captainslog
Jay, following on from dave-p`s comment regarding you knocking the bearings in with a hammer. how hard did you hit them? It doesnt take a lot to dent / crush / damage them, even slight damage will cause the shaft to rub. Have you withdrawn the shaft and inspected both ends for scrapes / scoring? might be worth a look. Iff yes then replace the bearings but heat the tube first, that way it will expand and the bearings can or should be eased in by hand. Then as the tube cools it will shrink back and seal the bearings in keith
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