drill prop. nut or not?

[PWR]

What does the panel think? The nut on prop shaft has guidance holes, no hole through the shaft though. Ought I drill through, with the nut in place, so as to create a hole for a split pin? My concern is there is nothing securing the nut.

 

[Rigger Mortice]

I can't comment on whether it is needed, but if you can drill that hole with hand held tools and accurately come out the other side you're better than I am. Drilling from both sides and trying to meet in the middle will also be difficult.
Personally, I would be thinking of taking the shaft out.

 

[ianat182]

I'd ensure that the nut is as tight as you can get it, then using a cobalt drill,constant speed and pressure drill through - which may take some time and maybe a second drill bit if both shaft and nut are stainless.

Using those 'titanium tipped' drills was a waste of time for mine and hardened the steel shaft locally, hence the cobalt option, though I used a castellated nut which was less work to drill, just the shaft.
You may be best to drill the nut first on a bench drill , then through it for your shaft marker, after tightening it.

ianat182

 

[vyv_cox]

A positive fixing such as a split pin is pretty much standard on all installations. I guess that a thread lock compound would help but a pin is going to be better. I have heard recently of a boat whose prop fell off, almost certainly because no pin was fitted.

As Rigger says, it won't be easy with a hand-held drill. Use cobalt drills and apply plenty of pressure and coolant to keep the drill running straight.

 

[PWR]

ta all for comments so far. Other thing is that the holes in the nut are not threaded, so not for grub screws. It was a major job getting the shaft back in when I took it out during the season after some straightening, so I am keen to do the job in situ if I can, and if it is needed.

 

[ianat182]

Sounds like the nut was intended for wire locking then.

ianat182

 

[SAMYL]

Make sure the nut is as tight as it should be then using the pilot hole in the nut drill through the shaft taking care to keep it as straight as poss.

You could possibly make a cleaner job of it taking the shaft out and mounting it properly but that is a lot of hassle for not very much gain.

If the shaft is stainless you will need good drills and LOTS of lubrication.

 

[PWR]

Sounds like the nut was intended for wire locking then.

ianat182

How does that work Ian please?

 

[rotrax]

Make sure the nut is as tight as it should be then using the pilot hole in the nut drill through the shaft taking care to keep it as straight as poss.

You could possibly make a cleaner job of it taking the shaft out and mounting it properly but that is a lot of hassle for not very much gain.

If the shaft is stainless you will need good drills and LOTS of lubrication.

Hi, I've said this before about drilling stainless-It is VERY important not to let the bit revolve without cutting. This will work harden the surface and make it almost imposible to gain any more depth. Use high quality bits from a proper engineers supply co. and ALWAYS apply high pressure to the bit while drilling.Use the lower speed if a two speed drill, and a little cutting oil,applied frequently-by another person so you can keep the bit cutting. Good Luck!

 

[ianat182]

This is a link to several methods of locking nuts better descriptions than I can give!

http://www.roymech.co.uk/useful_Tables/Screws/Locking.html

ianat182

 

[GrahamM376]

Our Featherstream came with Camlock washers as alternative to drilling.

http://www.alcatools.co.uk/Question-what-is-a-camlock-washer-92.aspx

 

[colhel]

A tab washer could be an alternative to the suggestions so far. You may need to drill a small hole in the prop (if there's not when there already) which would be a darn sight easier than drilling the shaft.
Is the prop on a spline or a taper?

 

[PWR]

A tab washer could be an alternative to the suggestions so far. You may need to drill a small hole in the prop (if there's not when there already) which would be a darn sight easier than drilling the shaft.
Is the prop on a spline or a taper?

on a taper

 

[colhel]

In which case a tab washer wouldn't be good enough (in my opinion).
just another quick question. Is the prop pushed on tight in that picture?, as there doesn't appear to be much thread thread showing and the nut almost looks like a half nut or has been modified anyway.

 

[Rigger Mortice]

This is a link to several methods of locking nuts better descriptions than I can give!

http://www.roymech.co.uk/useful_Tables/Screws/Locking.html

ianat182

That link doesn't work, but I got back to the home page and it looks as if that site has some really useful information on it. Thanks for posting it.

Now to find the bit that you were linking to!

 

[Poignard]

just another quick question. Is the prop pushed on tight in that picture?, as there doesn't appear to be much thread thread showing and the nut almost looks like a half nut or has been modified anyway.

I agree there's something odd about that set up.

Usually you would expect to see some thread showing aft of the nut and that would normally be a castellated nut anyway. Although some modern installations do use a Nyloc nut and an undrilled propshaft instead of a castellated nut there isn't room for one on your propshaft.

Perhaps the propshaft has been cut back for some reason? Maybe it was broken at the original pinhole?

 

[misterg]

It can be done in-situ (I've done it) - just good quality HSS drill bits. In my case, I was trying to drill a fresh hole after fitting a new prop, but broke into the existing hole which shattered the drill bit. I had to start again carefully from the opposite side & managed to match up with my original drilling so I could push the pieces of broken drill bit out.

It definitely came into the "I wish I'd never started this" category. If I were to do it again, I'd drill the shaft behind the nut and fit a castellated nut, a locking wire, or even just a split pin to stop the nut coming off. You don't have enough shaft protruding to do this, though. I'm not sure what the jury would think about tapping the hole in the nut & using a grub screw in it to lock against a prepared 'dimple' in the shaft (the nut looks big enough that you could get two grub screws down the hole - one to lock the other).

Bear in mind that if you decide to drill it, and the drill wanders, it might not come out in line with the hole on the opposite side of the nut, so you could need a drill bit long enough to reach the full diameter of the nut.

0.02p

Andy

 

[PWR]

No idea to be honest! Looking through the various comments it looks to me like:

1. some security of fixing is required
2. most practical is drilling through using cobalt bits and coolant (least upset to current set-up, least risk of damage, worst outcome is failing to get the drilling done)

So I'll go with that and let you all know what happens in due course. Thanks for the help (and please do comment if you see a better way).

 

[misterg]

...worst outcome is failing to get the drilling done...

Make that "..worst outcome is snapping the drill bit in the hole making it impossible to get the drilling done or get the nut off ever again."

On reflection, I would take the nut off and tap one of the radial holes.

When it's back on and tight, use a hand drill through the tapped hole to make a 'dimple' in the shaft. Fit a suitable grub screw to the tapped hole & tighten into the dimple. Fit a second grub screw behind the first to lock it in place.

Good luck, whatever you decide to do

Andy

 

[doug748]

I would be tempted to follow misterg's advice, nice and easy.

Generally I favour tab washers but this would push your nut even further out. The tab washer is simply an over size stainless washer that has a tongue emanating from the internal diameter. You put the washer behind the nut drift the tongue into the end of the keyway (I make the assumption you have a keyway), put your nut on and then bash the edge of the washer onto one flat of the nut. Low tech and can be reused.
These boys know their onions and always supply tab washers if you get a shaft from them, they will possibly supply one if you are interested:

http://www.coengineering.co.uk/

Easy to make one though.