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[spily]

Hi all, at the young age of 67 i have decided to get into model boats. What i would like to know is,how much end play/gap should there be between prop and o/shaft tube?. Mine has about 3.6mm, should it be packed with a nylon washer and what amount of free play would be right ?. Many thanks in advance, Paul.

[ben hall]

i put 2/3 mm ondipending what the model is dsighned for

a model that only goes forward does not need as much as a model that goes backward and forward and turns 

[spily]

Hi, thanks for your quick response, i may be a bit thick but have to ask. Is that two thirds of a mm or 2 to 3 mm ? Paul

[tonyH]

I must admit that I've always understood that the driving force from the prop should be carried by the stern tube and not the motor shaft. In other words, the gap should depend on how much movement you've got in the shaft coupling. That's why most couplings have splined sections - to allow for the movement.

I'm probably wrong in this but...........

Tony

[spily]

Hi Tony, perhaps i was not very clear with my question. I have a prop shaft that is not yet fitted, when each end nut is tightened it leaves 3.6mm approx of free play. This makes me think it wants a spacer or two limiting the end play.Your thoughts would be much appreciated,Paul.

[dreadnought72]

Is this the nuts tightened down to the end of the threads on the bare shaft?

If so, and when in use, don't forget that the nuts will be tightened against the prop at one end, and the coupling at the other - making it likely that they'll be more than your current amount of free play.

I'd recommend a washer (or two) at the prop end in order to trasfer the thrust onto the tube.

Andy

[unicorn]

 
                       Hi  ---   ideal situation would be a shaft end float of less than a 1/4 mm (10 thou) with washers on both ends
       of the shaft with the prop on and all nuts fully tightened this would then accomodate ahead and astern thrusts with no
       movement on the splines or the motor. Try greasing the shaft with a mixture of 50% graphite grease and lube oil.
           
                                   regards unicorn

[spily]

Thanks for your replies chaps, it looks like washers then. Very many thanks, you have all been a great help and no doubt i will be back soon with more newbie questions, although trawling through the question and answers helps greatly.Cheers Paul.