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[sunnybob]

So, after 18 months in refurb, i put it in the water, and got water coming through the prop shafts into the boat.
this is not good, I cannot modify the boat to put the inner ends above the water line, so how do I seal them please?
At the moment they are just plain brass rod inside brass tubes, nothing else.

[chingdevil]

Put some light oil/grease into the tube, do not fill too much as this will cause drag and overheat your motor. Fit a washer behind the nut/propellor against the tube, this will act as a seal not tight against tube minimum gap.

Brian

[nhp651]

I use a mixture of vaseline and carbon powder squeezed into the tube whilst the prop shaft is half into the tube, .use a syringe loaded with the stuff, and rotate the shaft as you are squeezing it in, finally pushing the shaft through the second bearing.....the whole tube will be now a barrier against water ingress......honestly.
neil.

[sunnybob]

I need something more specific please. make /model of light oil and grease?

And I have to admit I have never heard of carbon powder?

[TailUK]

I need something more specific please. make /model of light oil and grease?

And I have to admit I have never heard of carbon powder?

Graphite powder works as well and you can make enough for yourself either by sanding a soft pencil lead against sandpaper.  Try and avoid getting dust from the wooden part of the pencil in the graphite.  The second way this to use an old electric motor brush. (the graphite blocks that fit against the comutator)  Sand the brush down until you have enough dust to mix with the Vaseline.

[Netleyned]

Vaseline is a trade name for petroleum jelly found in pharmacists and supermarkets

Ned

[sunnybob]

The vaseline wasnt a problem, used to use that on my hair in the 60's when I couldnt afford brylcreem 
Surely this home made graphite grease is abrasive?
I have some water pump grease, so shall use that sparingly as a trial, but I'm concerned about friction heating. Should I be????

[HS93 (RIP)]

is it the old original shaft and if so had it got signs of wear ? because if the bearings are shot you may have difficulty sorting it without new bushes.
you may well find that you can fix it by just bushes or one of the new thin shafts and tubes that may well fit in side your old one so no repainting.

Peter

[john s 2]

Graphite is not abrasive as used. In Britain we can buy Graphite Grease for cars. If you dont wish to make your own Graphite then a Locksmith should have some. Its used to puff into locks. Providing your grease is not to thick  as Neil suggests friction heating should not occur. John.

[nhp651]

Surely this home made graphite grease is abrasive?

I wouldn't have recommended it, had it been abrasive!!....nor would I use it on my models.....it is, in fact a lubricant of the highest order!!!

[malcolmfrary]

Carbon takes many forms - graphite is a superb lubricant, diamonds, on the other hand, are not.  When carbon is compounded with silicon you get carborundum, active ingredient of grinding paste.  Don't know if it is available to the public, but we used to use some stuff called oildag, a new bottle with the label still readable said "a colloidal suspension of graphite in oil".  An excellent lubricant that didn't run away on a vertical surface and kept lubricating after the oil part had dried out.  It wasn't used in the wet, though.  If it got wet there was a serious leak in the roof.

[cuppa]

I use silicone fishing reel grease which can be obtained from most fishing tackle shops.
You can also buy silicone grease at a plumbers supplier.

Cheers
          Jon

[DickyD]

I use silicone fishing reel grease which can be obtained from most fishing tackle shops.
You can also buy silicone grease at a plumbers supplier.

Cheers
          Jon

I got my silicone grease from Westbournes. I tube, done 20 boats so far and loads left.

[scoop]

I use silicone fishing reel grease which can be obtained from most fishing tackle shops.
You can also buy silicone grease at a plumbers supplier.

Cheers
          Jon

Glad to see someone else is using silicone grease instead of vaseline and other petroleum greases. Other outlets for silicone grease are chandelries and RS Components.
I never use vaseline or general petroleum greases greases to lubricate or seal bushes, bellows etc as the petrol content will eventually perish them. I generally fill a small syringe with silicone grease then inject it into the bellows, shafts, seals etc just to make sure every part has been lubricated. 
However I do use marine greases to lubricate flexi and stub shafts on my race boats 
Never use a teflon based grease to lubricate a teflon bush/seal on a drive shaft, it will overheat and seize up !

Cheers
Scoop

[Timo2]

Hi

  Ref :- " carbon powder "   =   Graphite  Dry lube for door locks    

  very useful stuff.


 Timo2

[sunnybob]

ok, I'm starting to get the idea, but these are just tubes and rods here. there are no bushes, bearings, or seals.

I tried my water pump grease today.... FAILED 
Made some nylon spacers to remove front - back play.... FAILED 

there appears to be a fair amount of slop between shaft and tube, what are the chances of necking down the end of a 5mm brass tube to more closely fit the shaft ends?

[DickyD]

The way to get over this is to get two short [about 10mm] lengths of brass tube that will fit inside your prop shaft tube and still leave enough room for the prop shaft to pass through. Insert one piece in each end of the prop shaft and solder into position so forming a bush. Then use your grease and washers.

[sunnybob]

Dicky, nice idea, but where do I get brass tube of a 1/4mm wall thicknes?

I suspect theres a 1/2 mm, or at most 3/4mm discrepancy between the external diameter of the shaft and the internal diameter of the tube.

[TailUK]

Have a look at some of the posts by Krishna.  He's got some "outside the box" ideas about propshafts and such.

[dodgy geezer]

I have used these before - they work very well.

http://www.mikessubworks.com/page1.html


Alternatively, if you have access to a lathe, make up a seal unit using these..  http://simplybearings.co.uk/shop/index.php?cPath=19_4463

[John W E]

hi ya there

I have drawn a little 'scribble' which may help you out, by using brass tubing which fits over the top of your prop shaft & is soldered in place.   The only draw back with this is you may have to, somehow, shorten the length of the tube on the inside of your boat leaving the prop shaft the same length or you could do it on the outside of the hull if you dont have enough room on the inside.    The only other alternative, apart from this one, that I can think of at the current time is by placing a 'O' ring over your prop shaft so it runs against the outer edge of your prop tube.  Drawback with that though is that it puts an extra load on your motor.   

Aye, john

[John W E]

 

[HS93 (RIP)]

you could also do this only basic tools req you can epoxy the tube on if need be and you don't have to fit oiler tube


http://www.modelboatmayhem.co.uk/forum/index.php?topic=6401.0

Peter

[sunnybob]

Tailuk.... couldnt find any reference to krishna, or krishnah, on this site.

dodgygeezer..... no lathe, not much room to add length to the shafts.

bluebird, I'm thinking along those lines, but have very limited access to brass tubes here in cyprus. Hell, I have very limited access to brass!

hs93.... interesting, but your post doesnt mention the actuall bearing at all. Do you have a link to them?

at the moment, Im leaning towards burring over the rudder ends of the tubes, and redrilling them to a tight fit on the shafts. Plan B would be to add a reducing sleeve somewhere to the tube, but there is so little space that they would have to be fitted outside the boat, between the tube supports.
Looks like I backed myself into a corner here.

[TailUK]

You can see all of krishna's posts here.


http://www.modelboatmayhem.co.uk/forum/index.php?action=profile;u=7180

He makes a lot of the parts from salvaged materials