Tightening the dome nut on my prop

[Saltram31]

Just replaced my cutlass bearing and have re-installed the 2 bladed prop. I cleaned the key and key way to remove any burrs with wet and dry,greased the shaft and fitted the prop. My problem is that when tightening the dome nut ,I can not get the split pin and grub screw holes to line up with the ones in the shaft when fully tightened. I need to turn the nut back about quarter turn to line the holes up. The prop seems fully seated so not sure where the problem lies. Appreciate any help.

 

[PCUK]

Drill a new hole as the prop' has gone farther onto the shaft this time.

 

[Saltram31]

Drill a new hole as the prop' has gone farther onto the shaft this time.

The prop is only just clear of the shaft threads, so not sure if it has gone farther onto the shaft. I was thinking that it might not be high enough on the shaft due to it sitting on the key for some reason. Wondering if they used heat when they originally installed it.

 

[old_salt]

You want some shim brass and make a washer to go under the nut.
Set the nut up so the holes line up and measure the gap under the nut with feelers add a few thou for a good tight fit.
Make a washer to the feeler size plus a few thou.

 

[burgundyben]

I switched to tab washers to avoid this conundrum.

 

[Steve Clayton]

I switched to tab washers to avoid this conundrum.

+1

 

[cliffordpope]

You want some shim brass and make a washer to go under the nut.
.

You can't rely on the nut alone to exert enough force to seat the taper. Take the shaft out and thump it down on something solid. (Like seating an axe head)
As an alternatively to adding shims, you could grind down the back of the nut a little to the next alignment point.

 

[old_salt]

You can't rely on the nut alone to exert enough force to seat the taper. Take the shaft out and thump it down on something solid. (Like seating an axe head)
As an alternatively to adding shims, you could grind down the back of the nut a little to the next alignment point.

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Sorry, I have to take you to task on this but please don't take it to hart as a personal rant at you.

If you read the OP quote:-
My problem is that when tightening the dome nut ,I can not get the split pin and grub screw holes to line up with the ones in the shaft when fully tightened. I need to turn the nut back about quarter turn to line the holes up. The prop seems fully seated so not sure where the problem lies. Appreciate any help.
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You will realise the prop is held by a dome nut with a hole that should line up with the hole in the shaft.
I have never had to remove a shaft and thump it down on something solid. (Like seating an axe head)
and Some of the props I have fitted had a prop shaft 15" in dia 8,000 ton ships
No a good hit with a mallet /hammer and soft drift would do the job.
As for grinding down the back of the nut a little to the next alignment point.
If I was to go along that then it would have to turned down in a lathe, you would never get it bed all round the face without a lot of tedious work with engineers blue.
But it is not a standard castellated or slotted nut it is a Dome Nut with a hole and grub screws.
and it makes sense to line up the original holes in the shaft and Dome Nut.
So the only way he can go is to use a carefully fitted washer.
It would be bordering on a disaster waiting to happen if he was to drill extra holes though the shaft.
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Quote:
You can't rely on the nut alone to exert enough force to seat the taper.
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Why would it not seat the taper it works with ever taper I have fitted including track rod ends on wagons.
Any taper works on the fit not the amount of force exerted.
I quote Morse taper Drills not to mention all your boring /milling machine tool heads.
There is another couple of things,
The OP does not say the shaft has a taper or not I would presume it has also is the key a wood-rough or a feather.

 

[cliffordpope]

I'm just repeating what a marine engineer told me some years ago. I said that no matter how hard I tightened the nut, at the end of the season it was loose and needed tightening to the next hole. He told me that was in the nature of a taper - it needed a sharp shock to seat it fully. He always gave track rod ends a clout and then got a fraction more turn on the nut.
Up-ending the shaft was a useful trick for a small boat.

 

[Woodlouse]

To what sort of torque are you wazzing this nut up to? A torque wrench us usually required when fitting a prop and the pressure exerted, in my experience, is not that excessive so maybe backed off quarter of a turn with the split pin in is tight enough.