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  1. #31
    Join Date
    May 2007
    Posts
    39,084

    Default Re: Refitting the prop - dumb question

    Thin wave washers make good shims.
    If the nut is reversible, you could drill the other end to give alternative hole options?

    If you can work out what shim you need, one of the many spring or lock washer flavours might do it?

    The traditional method of course is to try drilling a new hole through the shaft, break the drill and tell yourself 'that won't move!'.

  2. #32
    Join Date
    Nov 2001
    Location
    Me: Johannesburg South Africa Yacht: Richards Bay East Coast Africa
    Posts
    7,347

    Default Re: Refitting the prop - dumb question

    To find out the thickness of a washer you can measure the thread pitch and measure the angle between the nut hole and the shaft hole when he nut i tight.

    Then packing washer thickness = thread pitch * hole angles difference / 360.

    Then you can search for a washer that thickness.
    Life is too short not to have a sea view
    Distantshaws tinyurl.com/yclt6l68

  3. #33
    Join Date
    Jan 2005
    Location
    Dorset
    Posts
    4,530

    Default Re: Refitting the prop - dumb question

    OP hasn't yet confirmed that it is not being prevented from tightening on the taper by the key.
    Put the prop on the shaft with the key in place. Shine a torch from the back of the prop, and see if you can see light between the key and the prop.
    If not the key needs filing down

  4. #34
    Join Date
    Jun 2016
    Location
    North West
    Posts
    593

    Default Re: Refitting the prop - dumb question

    I reckon he's just a pussy and needs to tighten it properly.

  5. #35
    Join Date
    Nov 2009
    Location
    Home UK Midlands / Boat Croatia
    Posts
    21,358

    Default Re: Refitting the prop - dumb question

    Quote Originally Posted by KREW2 View Post
    OP hasn't yet confirmed that it is not being prevented from tightening on the taper by the key.
    Put the prop on the shaft with the key in place. Shine a torch from the back of the prop, and see if you can see light between the key and the prop.
    If not the key needs filing down
    See post #30.

    Richard

  6. #36
    Join Date
    Sep 2001
    Location
    Home - Sothampton, Boat - Gosport
    Posts
    10,671

    Default Re: Refitting the prop - dumb question

    Quote Originally Posted by JBJag27 View Post
    I reckon he's just a pussy and needs to tighten it properly.
    I'll plead guilty to pussy - I don't have a lot of strength since sepsis and open heart surgery a couple of years ago, but I've got the nut as tight as I can get it using a 10" wrench and it needs to go another 1/12 of a turn, something over 0.1mm of thread pitch.

    I've either got to expand the bronze prop on the taper, compress the SS taper or stretch a roughly 15mm diameter SS rod by maybe 1% over the length available to stretch; in practice, I'd expect a bit of all three. I'm no engineer, so the calculations are beyond me - what sort of torque are we looking at to do that?
    Steve
    Never believe anything until it has been officially denied.

  7. #37
    Join Date
    Nov 2009
    Location
    Home UK Midlands / Boat Croatia
    Posts
    21,358

    Default Re: Refitting the prop - dumb question

    Quote Originally Posted by Stemar View Post
    I'll plead guilty to pussy - I don't have a lot of strength since sepsis and open heart surgery a couple of years ago, but I've got the nut as tight as I can get it using a 10" wrench and it needs to go another 1/12 of a turn, something over 0.1mm of thread pitch.

    I've either got to expand the bronze prop on the taper, compress the SS taper or stretch a roughly 15mm diameter SS rod by maybe 1% over the length available to stretch; in practice, I'd expect a bit of all three. I'm no engineer, so the calculations are beyond me - what sort of torque are we looking at to do that?
    If you have a torque wrench I would certainly try it and see what torque you are up to at the moment. I wouldn't go beyond 100 Nm but an M15 SS thread and nut would be fine even beyond that. However, I would use a shim/washer if I had to go beyond 100 Nm but that's just my personal preference.

    Richard

  8. #38
    Join Date
    Feb 2003
    Posts
    15,768

    Default Re: Refitting the prop - dumb question

    Quote Originally Posted by PetiteFleur View Post
    Yes - I can remember doing that as an exercise when I started my apprenticeship - what a useless exercise, filing a 4" long hexagon bar into a rectangle...
    Even more Gosh! when you realise that at the time the poster of this advice was advocating it when in reality the prop could have been riding on the key!
    Last edited by Heckler; 15-11-19 at 09:59.

  9. #39
    Join Date
    Oct 2018
    Location
    A Member State of the European Union
    Posts
    7,557

    Default Re: Refitting the prop - dumb question

    Quote Originally Posted by Heckler View Post
    Even more Gosh! when you realise that the poster of this advice was advocating it when in reality the prop could have been riding on the key!
    I like your new avatar but I never realised Boris was quite so tall.

    Wikepedia must be wrong because it has him as only 5'9".
    Last edited by Poignard; 15-11-19 at 10:32.
    "Brexit: like watching a library being burned down by people who can't read"

  10. #40
    Join Date
    Nov 2001
    Location
    Me: Johannesburg South Africa Yacht: Richards Bay East Coast Africa
    Posts
    7,347

    Default Re: Refitting the prop - dumb question

    Quote Originally Posted by Stemar View Post
    I'll plead guilty to pussy - I don't have a lot of strength since sepsis and open heart surgery a couple of years ago, but I've got the nut as tight as I can get it using a 10" wrench and it needs to go another 1/12 of a turn, something over 0.1mm of thread pitch.

    I've either got to expand the bronze prop on the taper, compress the SS taper or stretch a roughly 15mm diameter SS rod by maybe 1% over the length available to stretch; in practice, I'd expect a bit of all three. I'm no engineer, so the calculations are beyond me - what sort of torque are we looking at to do that?
    If you put some grease on the thread and nut /prop face you will be able to tighten the nut a little more without extra torque.

    Just remember some of the tightening torque will be taken up by the friction in the thread and nut/prop faces.
    Life is too short not to have a sea view
    Distantshaws tinyurl.com/yclt6l68

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