propshafts

[ANDY porterParticipant @andyporter91883]

hello im scratch building a ocean going tug boat at the moment.its twin screwed so you have right and left handed propellers.do you need left handed thread on left prop shaft or are all props the same thank you

Edited By ANDY porter on 06/02/2016 19:18:10

[ANDY porterParticipant @andyporter91883]

[ashley needhamParticipant @ashleyneedham69188]

Hi Andy and welcome to the forum.

All props are threaded the same, so no need for special threads. Props can be inwards or outwards turning it does not make much difference, although just sometimes it can have a small effect on the steering. It may be an idea once up and running to swap the props just to see if there is any difference, never know.

Ashley

[HaigParticipant @haig]

Hi Andy,

The only thing you need to watch is that you have a locknut on the propeller shaft and tighten it against the propellers, as one of them is likely to unscrew itself. I know as it has happened to me.

Contra-rotating propellers are easier to steer than both rotating the same way. I have 1/24 scale tug with Marx twin Kort nozzles with props that rotated the same way. After years of suffering to drive straight lines I have made my own set of opposite handed propellers and the difference was well worth the effort..

Haig

[ANDY porterParticipant @andyporter91883]

thanks chief good to know will apply thread lock to left handed prop.will post some pictures of build when i work out how

[ANDY porterParticipant @andyporter91883]

[ANDY porterParticipant @andyporter91883]

[ANDY porterParticipant @andyporter91883]

[ashley needhamParticipant @ashleyneedham69188]

Andy. Would not advise thread lock personally. A well tightened locking nut should be all that's required. Applying threadlock, especially the usual one as sold in DIY shops will effectively weld the prop on the shaft, making future maintenance difficult.

Loctite do a No 222 compound for small threads (I think that's the one) that is of lower strength. I have had a run-in with the normal Loctite on a 4mm shaft/bearing setup and had to get the hot air gun out to separate the parts…which is ok if said parts are on the bench.

I do not know if the other chaps use threadlocking compound…perhaps a few could post and advise?

Ashley

[HaigParticipant @haig]

Andy,

I agree with Ashley, A well tightened locknut is all I would use.

I regularly need to remove my propellers and propshafts for maintenance and greasing.

The tug hull looks interesting. Lots of challenging planking ahead. What is the type of tug and what scale is it?

Haig

[ANDY porterParticipant @andyporter91883]

thank s guys will try with just the lock nut and hope.she will be a ocean going tug when done.as to scale i dont really know the plan i have is at 1/200 on a4 paper downloaded from tinternet.then just measured of plan and x4 with a bit of rounding up or down.sees to be coming together ok planking was a mare

[ANDY porterParticipant @andyporter91883]

[HaigParticipant @haig]

Looking good. It will be all worthwhile when complete.

Regards

Haig

[AssociatedParticipant @associated]

I did not know propshaft sneed greasing , do you just smear a generous amount around inner and slide in of pack tube and push inner back through , prob I have got is from model boat bits and when spoke on phone got told the propshaft had to be made , so guess he made it up ?

Matt

[Paul TParticipant @pault84577]

Matt

There are many different opinions on lubricating propeller shafts, some say pack them with grease, some say use Vaseline others say use 1in3 oil.

The best thing to do is undertake your own research and test a few different forms of lubrication until you find one that suits you but basically as long as the shaft is lubricated and the lubricant used doesn't slow the shaft down then there isn't a problem.

On a personal note I have to say that Steve at Model Boat Bits has been involved with the hobby for many years and is a well respected and honest person always gives the best advice freely and with good grace. It is not fair to imply that he 'made it up' especially when you don't know what the correct answer actually is.

[AssociatedParticipant @associated]

Paul thanks , I do not see in the type of shaft how an oil would work . I'm thinking would run out as not a sealed shaft via oil seals . I think I would try a waterproof grease and go from there .

When I spoke to Steve on the phone he seemed very helpful and genuine which was 1st time spoke to him . Will be using him in future for sure . I don't judge people thinking they do not know what talking about but I'm a technician by trade so i may know when things don't seem right . Have learnt on other forums there are people trying to pull wool over others eyes as only really guessing for themselves. I am gratefull of all the help I have had on this form so far . A lot of very knowledgeable people on here .

Thanks , matt

[Paul TParticipant @pault84577]

Matt

You are correct about there being a lot of knowledgeable people on this forum and contrary to 'other forums' we only supply truthful answers to questions. But you should know that we don't tend mollycoddle people

As a technician you do have knowledge of how things work and have quite rightly pointed out that oil might not be the best lubricant (even though there are some very experienced people who will disagree) you suggest that a waterproof grease might be the best solution, which in itself seems a very plausible course of action but have you considered the effect of drag that the heavy waterproof grease will have on the shaft and how much motor power will be lost due to this drag.

Lubricating propshafts is an entirely personal thing and if you ask 20 model builders you will get 20 different answers so the only true way to find out is to do your own little bit of research.

Paul

btw I use lanolin oil and home made PTFE seals

[AssociatedParticipant @associated]

Yes Paul there will be a certain amount of drag with using grease . Not sure if there is a liquid grease that is waterproof??? Would be a better lubricant in my mind .

When you say that you have made your own seals from ptfe I assume ptfe sheet ? Looking at my prop you have the outer tube with soldered end caps where the hole I'm guessing is around 6mm roughly. Are you just making up a ptfe washer to sit behind the propeller and nut or are you somehow using a gland packing method ?

3 in 1 oil would lubicate the prop lovely but what about a thicker type of gear oil .

Matt

Edited By Matt B5m on 16/02/2016 20:54:38

[Paul TParticipant @pault84577]

Matt

In simple terms 'the heavier the lube the more the drag' this applies in all engineering disciplines from heavy engineering to watch making.

I made some PTFE seals from 2mm blue PTFE sheet that sit at the end of the shaft and is held in place with the nut, simple but very effective in keeping the water out.

Stuffing glands are great in ocean going steamships but no good in little model boats as they soak up to much motor power.

Before using PTFE I used to use outboard motor gearbox grease, just a blob at the submerged end of the shaft kept my hulls dry.

When you have built the Twinkler you can stick it in the bath and experiment with different kinds of lubricants until you find one that best suits your needs.

Now lets see some production photos.

Paul

[AssociatedParticipant @associated]

Thanks Paul . lets face it in my trade heavy plant machines the drag of heavy and light lubes dont make much difference .

once built will have to have a play in the bath .

matt

[Paul TParticipant @pault84577]

Hi Matt

A D8 towing a ripper could use wet concrete as a lubricant without any difference in performance. Mind you how the drivers treat the AD25s its surprising that any lubricants survive.

Looking forward to seeing the build progress.

Paul

[AssociatedParticipant @associated]

Quite true there ! Mainly do commercial and horticultural kit these days . Our Volvo fm400 hook loaders get a lot of abuse getting stuck on muddy sites and pushed out while been driven by agency drivers who seem to somehow leave in high range !

Wood was ordered last night as posted on "twinkler build" topic . Has anyone ordered from slecuk before ? How quickly do they dispatch ?

Matt

[Paul TParticipant @pault84577]

Hi Matt

I had no end of bother on one site when a tipper truck became stuck and instead of getting a chain to be pulled out he asked one of the excavator drivers to give him a push………..the excavator was a Komatsu 450 and it pushed the full tub straight off the chassis.

The HSE had me tied up in meetings for days.

Slecuk are very good and you wont have any problems.

Paul

[AssociatedParticipant @associated]

I bet ! You do see some funny ideas and seights! Least when the hook Volvo hook lorrys pushed there pushed on rear chassis !

Had a email to say order dispatched so hopefully start some work this weekend !

Matt

[ANDY porterParticipant @andyporter91883]

thanks haig im getting there. just something i was thinking about.if you use a light oil does it not leach out of prop and contaminate pond you are sailing on.heavy grease is probably worse for oil slik behind boat.what about using the water proof props andy p

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