Removing propeller from taper shaft

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Plevier

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I want to remove the fixed 2 blade prop from my boat which has a standard Beneteau 25mm taper shaft with key.
I'm wondering what torque the nut is likely to be and how much of a job it normally is to get the prop loose from the taper? I'm fitting a Kiwiprop and that specifies 20lbs.ft, is the original prop nut likely to be similar tightness?
Puller? Heating? Bronze/brass drift (I don't like that one - it will shock the gearbox - but our local engines man suggested it)?
What I normally do with car taper joints is hold a weight one side and hit the other side sharply. That normally jars them loose. Does that work with props?
Experience based advice appreciated!
 
Slacken the nut until the end of the shaft is just inside the outer face and then hit it fairly hard with a hammer. Unlikely to damage the gearbox as flexible coupling will absorb the shock at that end. Even if you use a puller, it still needs a "shock".
 
Willow3 said:
I want to remove the fixed 2 blade prop from my boat which has a standard Beneteau 25mm taper shaft with key.
I'm wondering what torque the nut is likely to be and how much of a job it normally is to get the prop loose from the taper? I'm fitting a Kiwiprop and that specifies 20lbs.ft, is the original prop nut likely to be similar tightness?
Puller? Heating? Bronze/brass drift (I don't like that one - it will shock the gearbox - but our local engines man suggested it)?
What I normally do with car taper joints is hold a weight one side and hit the other side sharply. That normally jars them loose. Does that work with props?
Experience based advice appreciated!
Click to expand...
If you don't have a puller the couple of lump hammers on either side of the boss work a treat. In fact it's probably the standard method professionals use when you're not looking.

I've used it the 4 times I've had to take a prop off - have the nut on or you'll lose the key when the prop falls off.
 
GrahamM376 said:
Slacken the nut until the end of the shaft is just inside the outer face and then hit it fairly hard with a hammer. Unlikely to damage the gearbox as flexible coupling will absorb the shock at that end. Even if you use a puller, it still needs a "shock".
Click to expand...

Thanks but it doesn't have a flexible coupling, it's rigid.
 
charles_reed said:
If you don't have a puller the couple of lump hammers on either side of the boss work a treat. In fact it's probably the standard method professionals use when you're not looking.

I've used it the 4 times I've had to take a prop off - have the nut on or you'll lose the key when the prop falls off.
Click to expand...

+1
 
You will just have to try increasingly aggressive methods until you succeed. On my present boat, the firts time , I had to remove the shaft and prop, Take them home and put them in the vice and then apply serious heat to the prop ( propane torch) when it came loose with a hit with a hammer. Nothing else would shift it.
 
Lakesailor said:
He's replacing it anyway.
The two hammer technique needs good synchronisation.

You can hire pullers.
Click to expand...

Depending on tools available you could also angle grind it off.
I've done this before where the use of pullers, heat, lump hammers has become increasingly more aggressive and I've become worried about distorting the shaft.
(Applicable only if you are replacing it.)
 
1. Puller, lots of force on nut; heat the prop hub; tap/hit the side of the hub repeatedly;
2. More force on puller, more heat; more tapping/hitting side/forward end of hub (difficult on a Bene I know)
3. More of the above.
4. Get the yard to do it......... :D:D
 
BAtoo said:
1. Puller, lots of force on nut; heat the prop hub; tap/hit the side of the hub repeatedly;
2. More force on puller, more heat; more tapping/hitting side/forward end of hub (difficult on a Bene I know)
3. More of the above.
4. Get the yard to do it......... :D:D
Click to expand...

The force on the puller will be thru the propshaft not the nut, once the intially force is on the prop it will pop off, as long as the shaft is tapered.
 
Problem is that many owners don't realise just how careful you need to be when tightening taper fittings. The figure quoted, 20 lb.ft., is quite a low torque. If your prop has been fitted by someone who applied a torque consistent with the nut size on a non-tapered fitting you could have a real struggle.

I would never hit the prop directly along the shaft axis, even with a wooden or brass drift, even with a flexible coupling. There will always be a risk of damage using a heavy enough blow to release a prop that is hard on. The opposed hammers on the boss often works well but the hammers need to be heavy - you are attempting to distort the boss that is significantly thick, so a 1 lb hammer will do little for you.

A puller is undoubtedly the best from an engineering point of view but it can often be difficult to get the claws of it to hold on. I find a big hose clip tightened around them may prevent them from slipping off. Sometimes a sharp tap on the hexagon end of the puller is needed, after tightening as much as seems possible.
 
vyv_cox said:
A puller is undoubtedly the best from an engineering point of view but it can often be difficult to get the claws of it to hold on. I find a big hose clip tightened around them may prevent them from slipping off. Sometimes a sharp tap on the hexagon end of the puller is needed, after tightening as much as seems possible.
Click to expand...


This is what was used to get my prop off.


proppuller001.jpg
 
vyv_cox said:
Problem is that many owners don't realise just how careful you need to be when tightening taper fittings. The figure quoted, 20 lb.ft., is quite a low torque. If your prop has been fitted by someone who applied a torque consistent with the nut size on a non-tapered fitting you could have a real struggle.

I would never hit the prop directly along the shaft axis, even with a wooden or brass drift, even with a flexible coupling. There will always be a risk of damage using a heavy enough blow to release a prop that is hard on. The opposed hammers on the boss often works well but the hammers need to be heavy - you are attempting to distort the boss that is significantly thick, so a 1 lb hammer will do little for you.

A puller is undoubtedly the best from an engineering point of view but it can often be difficult to get the claws of it to hold on. I find a big hose clip tightened around them may prevent them from slipping off. Sometimes a sharp tap on the hexagon end of the puller is needed, after tightening as much as seems possible.
Click to expand...
Going back to the days when I was an apprentice, taking the engine out of my mini, changing big end shells and mains, The torque was 25 ftlbs on a 9/16" spanner so probably a 3/8" bolt. It wasnt a lot, a good pull on the spanner was all it took.
Having said that, I have a 10" movie spanner that I use on the prop nut, a good **** with the side of a ball pein hammer is all it takes/took on my 351 (25 mm) and 381 (30mm)
I have a cheap 2 legged puller, chinese £12, that I use, the fingers just grip the boss on the prop. I knock up the tab washer, undo the nut but leave it on to catch the bits when the prop comes off, harden the puller up hard with the 10" movie spanner, then tw at the end of the puller nut sharply. Ping off the prop comes. Tightening up I harden it up with the movie spanner then **** it around half a turn. I know it has gone back because I use the same lock tab and it lines up.
Stu
 
Removing F-o-F props

The engineer said:
puller
Click to expand...

Second.

For people having to remove a 3 bladed Flex-o-Fold it does exist a 3-pronged puller (on sale from FoF, but any blacksmit can manufacture one for You): take a round piece of steel, the diameter a couple of inches bigger tan the propeller's (blades excluded) diameter, have it cut so to look as a 3-ray star (rays 120° from each other, wide as the space where the base of the blabe is hinged) with a threaded (M10 or above) hole in the center. Remove blades, position the "star", put in place the s/s hinges over the "star" and start screwing the M10: it will soon engace against the center of the body and the "rays" will start pushing the prop body out.

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Presto, nice and clean.



[Ehrr, how do I post a picture??]
 
Last edited:
Lakesailor said:
He's replacing it anyway.
The two hammer technique needs good synchronisation.

You can hire pullers.
Click to expand...

I would like to keep it though - in one piece! It's in good nick (so far).

I don't usually try to synchronise two hammers, that is difficult - I hold a large weight one side and use a hammer the other side.

I think I will try that and go to the mobo place next door if I get stuck.
 
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