holding the shaft stationary while torqueing the prop nut – how?

[pandos]

I have found that it is possible to put a lot of force into a shaft which is held by wrapping a length of sling around it a few times and securing it to something,

 

[BabaYaga]

What do you have inside the boat ? On my 25 - I have a reasonable length of shaft between coupling and stern seal ...

I have found that it is possible to put a lot of force into a shaft which is held by wrapping a length of sling around it a few times and securing it to something,

My shaft is quite short, about 100mm or a little less between half coupling and shaft seal.
Still may be worth a try, if I could anchor one end of the sling to the half coupling and take the other around a substantial piece of timber.

 

[Never Grumble]

Try looking on Darglow website sure they cover this on there.

 

[Refueler]

My shaft is quite short, about 100mm or a little less between half coupling and shaft seal.
Still may be worth a try, if I could anchor one end of the sling to the half coupling and take the other around a substantial piece of timber.

You would be surprised how little you need to anchor the end of the strap / rope ... the trick is to trap it under the tightening wraps of strap / rope ... the wraps are best repeated over each other to create a few layers as well - to further tighten the grip ...

It will slip while tightening ... but will once first wrap starts to grip progressively tighten to an iron grip ...

Like a Timber Hitch - it gets its grip from friction.

 

[andsarkit]

A wire rope clamp on the shaft would enhance the grip of the rope suggested above.
Clamp

 

[Refueler]

A wire rope clamp on the shaft would enhance the grip of the rope suggested

If using a Pipe Clamp as you suggest - no need for the rope .... get a metal bar that can lodge into the nut part and then you don't score the shaft .. or risk blade etc.

But honestly - if using rope .. trap end under turns and you'd be surprised at the grip ...

If that fails - Timber hitch - then wrap turns ...

Do not use any hitch or knot greater than that - as it will then be a knife job to remove ...

 

[rogerthebodger]

A wire rope clamp on the shaft would enhance the grip of the rope suggested above.
Clamp
View attachment 169893

Any old U bolt with a flat bar with 2 holes drilled to suit the U bolt. width

 

[Never Grumble]

 

[BabaYaga]

Thank you all for your replies and Happy New Year!
When this task comes up next time I think my conclusion will be to use the approach outlined in post #10. A rope or sling wound around the shaft might work, but I guess a steel bar resting on the hull inside will give a more distinct stop to torque against. I would be reluctant to put a clamp directly on the shaft, for fear of damaging the surface (PSS shaft seal, o-rings on rotor...)

Thanks also for the video link. Yes, timber at the blade root to stop rotation, but the torque specified on the nut was 45 ft/lb. That is just over 60 newton metres, if my online converter is correct. The figure I was aiming for was 220 nm – quite a difference.

 

[rotrax]

Yes, probably the best approach. Perhaps a steel bar with matching holes for two of the bolts on the halv coupling flange.

View attachment 169871

Almost exactly what I did to tighten a friends feathering prop. It was an eighteen inch flat blade screwdriver of the kind where the steel goes right through the handle. A hefty piece of 2X4 against the engine bay side, my friend holding it in place. Under one nut, which had been turned to give the grearest space for the screwdriver. Kept the shaft still a treat, took but moments. Biggest problem was finding and cutting the timber.

No torque wrench, this one was tightened so the split pin hole lined up. The screwdriver survived, the tip a tad out of line after the job was done

 

[rogerthebodger]

Almost exactly what I did to tighten a friends feathering prop. It was an eighteen inch flat blade screwdriver of the kind where the steel goes right through the handle. A hefty piece of 2X4 against the engine bay side, my friend holding it in place. Under one nut, which had been turned to give the grearest space for the screwdriver. Kept the shaft still a treat, took but moments. Biggest problem was finding and cutting the timber.

No torque wrench, this one was tightened so the split pin hole lined up. The screwdriver survived, the tip a tad out of line after the job was done

I did not use a torque wrench eor my prop nut either

Any one who has rebuilt engines or done practical engineering gets used to being able to estimate the tightening torque.

The only time I use a torque wrench is main and big end bearing bolts and head hold down bolts where uniform
tension is more important

220 nm does seem a high torque especially a tab locking is used

 

[Refueler]

Thank you all for your replies and Happy New Year!
When this task comes up next time I think my conclusion will be to use the approach outlined in post #10. A rope or sling wound around the shaft might work, but I guess a steel bar resting on the hull inside will give a more distinct stop to torque against. I would be reluctant to put a clamp directly on the shaft, for fear of damaging the surface (PSS shaft seal, o-rings on rotor...)

Thanks also for the video link. Yes, timber at the blade root to stop rotation, but the torque specified on the nut was 45 ft/lb. That is just over 60 newton metres, if my online converter is correct. The figure I was aiming for was 220 nm – quite a difference.

Are you sure about the nm ?? Take note that is a figure that is serious ...

 

[Refueler]

I did not use a torque wrench eor my prop nut either

Any one who has rebuilt engines or done practical engineering gets used to being able to estimate the tightening torque.

The only time I use a torque wrench is main and big end bearing bolts and head hold down bolts where uniform
tension is more important

220 nm does seem a high torque especially a tab locking is used

Plus Torque Wrench is vulnerable to bad thread etc ... its why when I raced - we used 'torque washers' ..... washers with tabs on that crushed at the torque levels ...
Guy would use normal spanner - with a feeler gauge to check when reached required torque.

I suppose such old solutions are not used now ?

 

[rogerthebodger]

Plus Torque Wrench is vulnerable to bad thread etc ... its why when I raced - we used 'torque washers' ..... washers with tabs on that crushed at the torque levels ...
Guy would use normal spanner - with a feeler gauge to check when reached required torque.

I suppose such old solutions are not used now ?

Torque washers and tab washers have different functions.

I do prefer positive locking on important fitments like head bolts and flywheel bolts that on perkins engines use a twin bole tab washers (I just rebuilt a 4 236

 

[Refueler]

Torque washers and tab washers have different functions.

I do prefer positive locking on important fitments like head bolts and flywheel bolts that on perkins engines use a twin bole tab washers (I just rebuilt a 4 236

Who's talking torque washers vs tab ??? Two are completely different functions ...

We used torque washers to get torque required without the 'field errors' torque wrenches were prone to ...

In fact if you wanted to - you could use both torque and tab washers in same ... so where's your point ???

 

[rogerthebodger]

Who's talking torque washers vs tab ??? Two are completely different functions ...

We used torque washers to get torque required without the 'field errors' torque wrenches were prone to ...

In fact if you wanted to - you could use both torque and tab washers in same ... so where's your point ???

The OP said the nut he is torquing up is locked with a tab washer and he is using a torque wrench and no one brought up torque washers

Am I not allowed to comment on your threads

 

[Refueler]

The OP said the nut he is torquing up is locked with a tab washer and he is using a torque wrench and no one brought up torque washers

Am I not allowed to comment on your threads

Of course you can comment - but you have mixed up two matters that have ne bearing on the problem.

Yes he is using tab washer .. but he is also having problem using the torque wrench. The two are not related ... I mentioned that instead of torque wrench - we used torque washers due to any bad thread can throw a torque wrench ...
Use of Tab washers with either toque wrench or torque washers is common place.
I only mentioned washers as another had commented on the wrench.

Where is the problem ... please enlighten me ...

 

[rogerthebodger]

Of course you can comment - but you have mixed up two matters that have ne bearing on the problem.

Yes he is using tab washer .. but he is also having problem using the torque wrench. The two are not related ... I mentioned that instead of torque wrench - we used torque washers due to any bad thread can throw a torque wrench ...
Use of Tab washers with either toque wrench or torque washers is common place.
I only mentioned washers as another had commented on the wrench.

Where is the problem ... please enlighten me ...

In my view the OP's issue are two fold.

1) The torque he is trying to tighten to is too high for the setup the video says 45 ft lbs

2) the wood prop he wa using was just too soft to support the torque he was trying to set

Would like to know what the supplier says about torque requirements

 

[NormanS]

What is the diameter of the shaft? And more importantly, what is the diameter of the thread for the propeller nut?
220 Newton metres is an awful lot of torque.

 

[B27]

Are you sure about the nm ?? Take note that is a figure that is serious ...

M20 bolt in 8.8 grade steel, typically spec'd around 500Nm max.

I don't know how big the OP's prop shaft is but it's going to be m16 or bigger?