Propshaft lubrication and setup

[Brian FryParticipant @brianfry61832]

I am building a 24 inch electric day boat and I am about to fit the propshaft.

 What I would like to know is what to lubricate the shaft with – the inboard end of the tube will be above water level – and how much.

I would also like to know is whether it is correct to arrange any longitudinal play in the motor/shaft assembly such that the thrust load is taken by the prop securing nut (forward of the propeller) rather than by the motor bearings.

 Any advice would be welcome

 Thank you

[Charles OatesParticipant @charlesoates31738]

Hi Brian, 2nd point first, your’e right, it’s not good to get the load on the motor bearings so a tiny amount of longditudinal play is needed. I go for the least that ensures free play of the shaft.

 Lubrication is a theme that will get you many different answers. Many modelers use oil, the grade isn’t important in many models unless you are going for maximum power transmition. A favourite method is to put in an oiling tube, a tube soldered into a hole drilled into the shaft tube just behind the coupling. This allows easy oiling.

    I have stopped useing oil because polution is a big deal these days, I prefer silicon grease, a small tub from a plumbers merchant will last for years and is cheap. The only downside it that it absorbs a small amount of power from the motor but this isn’t important to me. Last point, a little is enough with any grease. a solidly packed tube will absorb a lot of power and can strain the motor.

 I hope that helps, you’ll probably get some more answers now with other ideas.

 Chas

[Brian FryParticipant @brianfry61832]

Thank you Chas,

You have been a big help  – everything you  said made good sense and  I will try your silicon grease solution in my boat

 Brian 

[John W EParticipant @johnwe]

Good morning there Brian

I totally agree with what Chas says  in his posting – the only thing I would add is, if this is a new set up – i.e. it is a brand new prop shaft and motor; what I would strongly recommend is to run the motor and propeller shaft in situ for about half an hour to an hour – allowing the prop tube and motor bearings to bed in.

Whilst the motor is running, you can check for excessive tight spots, which will be indicated by excessive heat.  Once you have ran the motor in, remove the propeller shaft from the tube, cleaning all old grease out and then renewing the grease.   This you will find will make the motor and propeller shaft run a lot quieter – hope this is of some help.

aye

John 

[Brian FryParticipant @brianfry61832]

Thanks John,

Your additional advice was something I had not considered concerning the propshaft bearings 

Regarding tight spots in the motor, we are talking about electric motors aren’t we?

Thanks, 

Brian 

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[John W EParticipant @johnwe]

Hello there Brian

 Brand new electric motors are not ‘supposedly’ needed to be ‘run in’.   However, I have always put a light splash of machine oil on the motor bearings, whilst running the prop shaft in.   This I then wash off with methylated spirits or some cleaning agent and then re-apply 2 or 3 drops of clean machine oil.  That is very light machine oil by the way, similar to what they use on model railways locomotives and sewing machines.

 Hope this is of some help.

 aye

John

[Brian FryParticipant @brianfry61832]

Thanks for clearing that up, John!

 Brian 

[Brian FryParticipant @brianfry61832]

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