Prop sealing

[Bob Abell 2Participant @bobabell2]

I`ve always had trouble sealing prop shafts…………Using grease

Just discovered a novel idea…………..It `s probably been done before, but this is new to me.

I was going to fit a stuffing gland to my Great Eastern model but couldn`t assemble it into the boat due to the oil filler tube…………..then the idea struck me!

Make a piston to fit the filler tube and simply keep ramming down the grease with the piston……..Good idea?……………..I think so!

Bob the Inventor

[TelstarParticipant @telstar]

Bob       Beware oh beware!!

Packing bearings etc with grease can take an awful lot of power away from your drive.  On a different website a modeller was complaining his motor was drawing 8A on 6V out of the water. Some of his observations prompted me to tell him about a job I had to fix.  

I was called to a problem when a electrically driven fan ( that had worked happily for the last few month had suddenly started tripping the overloads and refusing to run.  The cause was eventually traced to a ‘helpful’ production worker who had greased the fan bearings with a pump grease gun.  the grease caused the bearings to go tight.  

The modeller had packed his proptube them pushed the shaft in, removing some of the grease brought his no load current down to less than 3A.

I am a firm believer in oilfilled propshafts I know they need more attention but they absorb less efford from the drive

Cheer Tom

[Bob Abell 2Participant @bobabell2]

Thanks for that Tom……………..I`ll do a few tests when the time arrives

I`ve never used an oil filler tube before………….Does it keep the water out?

Jeanie Deans has a bilge pump…………No prop shaft of course but the water gets in from somewhere

All other prop shaft boats let water in!

Do you know?………..Electric motors run quite happily…FULLY EMERSED!

Bob the Wet

[Bob StewartParticipant @bobstewart58500]

I initially lightly greased the propshaft and maintain with oil. No water leaks and no drag on the motor with nice smooth operation. Worth a try

One Bob to Another

[TelstarParticipant @telstar]

Hi Bob ……….I use oil in preferance to grease..            with the oil filler tube, I extend it to an accessable point and above the water line, usualle with flexable plastic tube (a medical dripset does a lot of models). then when I fill the system to the top I have a ‘head ‘ of oil above the water. The clear plastic tube lets me see the oil level. I think you will find even a fairly thick oil gives less drag than thin grease.

Your motor cooling system is effective, but sometimes sinks the boat. I had at one time a SAAB petrol injection car  on that the petrol flowed through the motor past the brushes, I’m glad no air got in..

To change the subject..

When doing rivets, I was once shown a dressmakers pattern wheel ( a bit like a cowboys spur) The chap used it  to run along shim brass it gave a row of dimples a bit like rivets, he used a guide to keep them in line.    I have put a picture of one on my gallery (when it goes active)  using this as a patterrn I used a modified gear wheel out of a clock it worked ok ( the mod was to file away every other tooth to give better looking spacing, I’m not a rivet counter). ALL thos rivets one at a time on G E  wow

its looking good though

cheers Tom

[Bob Abell 2Participant @bobabell2]

Many thanks to the other Bob and Tom

I like the plastic tube idea because at the moment, …….I can`t get near it!…..but with the tube……problem solved. Now why didn`t I think of that?

The single rivet method wasn`t too boring really……….it gave me time to think!

Bob the Rivetter

[Bob Abell 2Participant @bobabell2]

Hello Tom

Just had a look at your cowboy spurs………..OK, …..But I think the single punch method produces more distinct rivets?

Bob the Punch

[neil hpParticipant @neilhp]

Gents, the info that you have just given me has been invaluable.

 I have always used graphite grease in my prop shafts, and always had slow revving motors driving tugs/trawlers etc but I am working on a fast "interceptor" pilot boat with twin torpedo 850’s running off 12v as my present project.

I have just packed the tubes as normal with grease, and the performance is, to say the lease, not what I was expecting.

any ideas on how to get this grease out, please? any help greatfully appreciated.

cheers,neil.

[HS93Participant @hs9317166]

IRacing cars n the earley 80s we would run electric motors in a glass of water to bed the brushes in so there was no spark to burn the armature, shops decided to start selling them  as water dipped, then the problem arose, when we  started to do it  we would then clean the motor , they did not and they would rust. badley.. the other thing is you only needed to run them for 5 seconds for them to bed in 20 seconds and NO brushes left.

the way round the water in boat is to fit a small  s s sealed bearing and a tufnoll one at the prop end and just light vegetable based oil , no poluthion no water.simple

Peter

[Marc BlumParticipant @marcblum43457]

Hi,

I’m new to the model boat hobby, but I was reading about the water problem. I’ll tell you what I did to solve my water problem. I soldered a small washer to the prop tube, making sure that it was straight. Then I put a rubber grommet from a Futaba servo on the shaft and installed the prop snuggly (not tightly) against grommet. No water!

Marc

[John W EParticipant @johnwe]

hi there all

Normally when I first install propeller shafts and motors into a model; I pack the propeller tubes with a medium grease, also lightly oil the bearings and bushes on the motors; connect the motors up without any speed controllers or anything – to a 6 or a 12 volt battery (depending on the motor size) and allow to run for at least an hour.   This beds the bushes in the propeller shafts in, and also the bushes on the motor.

After the motor has been running for about say 1 – 1 1/2 hours; I remove the prop shafts from the tubes; clean out all the grease from insides of the prop tubes, normally flushing through with paraffin or white spirit.  Then replacing the grease with a couple of drops of very light machine oil or sewing machine oil – in with this I have a syringe that has a light machine grease which was supplied from where I used to work  and I only put a tiny amount of grease in the shafts – so much so you should be able to spin the shaft freely by hand.   After I have done all of that I reassemble motor and couplings and run the motor straight from the battery again for approx 5-10 minutes.

I know sometimes, some folk say, you shouldnt run brand new stuff in – flat out – you should actually build the speed up gradually, but I must confess I have never done that on electric motors.   Yes, I have gradually build up speed on steam and diesel motors, but as I say never done that on electric ones – and I have never encountered any problems.

To be honest the only problems I have ever encountered like that was created by ‘poor’ plastic coupling bodies; where the brass inserts either end have been mis-aligned.

Aye, I do hope that is of some help  John e – (bluebird under cover )

[bargemasterParticipant @bargemaster]

Hello Bob Abell

Reading with interest the prop sealing thread.I have only made 1boat model so am a total novice but must admit I used grease of some kind or another when the model was done some 30 years ago.I resently dug it out of storage (hasent seen light of day for some 25 or more years) and the prop still turns but the rudder tube is frozen and has collapsed the flooring and hull around it .What interested me the most about the posts was that water should get in at all.(showing my novice side here ,thought the prop shaft tubing at the end for the motor  would be above the water line.)I guess on some models that is impossible and hence the need to seal. You know when I looked at the plan for the steam tug dusty miller the first thing i noticed was where the prop shaft ended, it seamed to be under the water line and being a novice thought it strange but not game to ask in case everybody jumped on me and shouted " FOOL " Hey maybe they do that anyway but your article enabled me to ask is this common,do many model boats have  the prop shaft that low, if so them would a small o-ring work. So many questions.

 regards Glen

[Bob Abell 2Participant @bobabell2]

Hello Glen

All prop shafts are normally below the waterline!…….unless you had a steeply inclined one that emerged at the motor end….above the waterline…ie…….a speedboat.

An "o" ring will work but also will create a lot of friction…….I`ve used them quite a lot in my yachts where power amd speed is not important

Regards Bob

[bargemasterParticipant @bargemaster]

Hello again Bob

Yes i suppose i never had my thinking stuff in gear cause ive seen some model subs and never given a thought to the screw shafts . The photos of Dave Mannings Sub in gallery under Type VII is an inspirational model and top example. Will post a photo of my old girl soon but its not detailed in any way and when i look at the models in here maybe i shouldnt  till she get a face lift (and an interior in the cabin just to start with ).Its been thrown around the garage for many years and is in bad shape but have really got the bug to fix it and float it. Thanks for your time Bob,

all the best Glen.

[Bob Abell 2Participant @bobabell2]

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