Heat my prop.

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Oscarpop

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So I spent 4 hours this morning with a series of hammers and a gear puller trying to get my prop to loosen off its tapered shaft.

No joy.

Will start again tomorrow and will use a heat gun to heat up the prop to expand the metal.


Firstly, any suggestions as to how hot? Or is it just as hot as it gets?.

Second, any other suggestions?

I propose to tension the puller and then heat the prop. Hopefully the b#gger will pop off.
 
Oscarpop said:
So I spent 4 hours this morning with a series of hammers and a gear puller trying to get my prop to loosen off its tapered shaft.

No joy.

Will start again tomorrow and will use a heat gun to heat up the prop to expand the metal.


Firstly, any suggestions as to how hot? Or is it just as hot as it gets?.

Second, any other suggestions?

I propose to tension the puller and then heat the prop. Hopefully the b#gger will pop off.
Click to expand...


a gas torch will apply the heat much quicker, to the prop & not the prop + shaft.
apply the puller then a sharp tap with 2 hammers from 2 sides at the same time should do the trick.
 
This really is the length of a piece of string... I made the mistake of getting my folding prop a little hotter than I intended and the nylon bump stops deformed a little! So long as you stay hand hot it won't affect the metal, you don't want to get it red hot, but in cold weather a lot will be lost before it penetrates to the hub which is what you're trying to expand. I was lucky and did it in late Spring and the temperature change overnight did the trick and I found the prop and puller on the ground next morning.

I'd put the tension on the puller and then with either a hot air gun or blowtorch take the prop up to a sort of "ouch" temperature - with any luck, the heat should get to the centre of the hub maybe ten minutes later so be patient and prepared to input more heat every few minutes if it's cooling rapidly.

Rob.
 
Some props have a small machine screw in the side of the boss, which needs to be released, and this I have overlooked or forgotten about in the past, leading to much frustration and exhaustion, before I then realised my error!
Antifouling had filled the socket of this set-screw, and made it hard to spot in the gloom of beneath the boat.
Good luck in getting it off!
 
paulclan said:
Some props have a small machine screw in the side of the boss, which needs to be released, and this I have overlooked or forgotten about in the past, leading to much frustration and exhaustion, before I then realised my error!
Antifouling had filled the socket of this set-screw, and made it hard to spot in the gloom of beneath the boat.
Good luck in getting it off!
Click to expand...

Many thanks, I checked but will check again.
 
If it is a fixed, manganese bronze prop it is close to impossible to overheat it with a butane fired or paraffin blowlamp. Think plumbing fittings - it is common to solder to brass, melting temperature well over 200C, without damaging the brass. The mass of a fixed prop hub is too great to get that much heat into it with a small flame. Make sure the heat is applied all around to avoid permanent distortion.

As said already, bang opposing sides of the hub simultaneously with the biggest hammers you can obtain. I have used 4 and 7 lb hammers together. Don't be tempted to hammer the prop off the shaft axially, the force is being taken by the output bearing in the gearbox.
 
put your puller on and tighten HARD, then clout puller from shaft center, if nothing happens leave overnight, temp. gradient during night should do the trick.
 
Always done it by 'ringing', two hammers as above. I actually use a 20kg dead weight and 4lb lump hammer, never needed more than four hits. I would be wary of heat, don't know if it's the same but I tried to open a bronze deck fitting, only a few threads and 100mm diameter. In the end it went home to a gas axe, and it remains shut to this day.
 
I couldnt shift mine with hammers so resorted to heat. Used two blow torches with the pullers putting on as much force as possible. Had to get it really hot then it suddenly fell off. So be carefull not to damage the prop by hitting the floor! I was lucky. The pullers hit the floor first.
The faster you heat it the better so that the different rates of expansion release the grip.
Hammering can damage the gearbox so much better to use heat in my opinion.
A wet rag round the shaft will reduce the heat going up the shaft and damaging the cutlass bearing.
 
Same message - get the prop hub nice and hot either use a heat gun or blow torch at least as hot as when you dont want to touch it. If it does not just tap off give a wallop as already described already. I always used a wood block, but mine came off after a couple of whacks and slid down to the nut. As has been mentioned, leave the nut on the shaft as they tend to go suddenly and the prop will fall on the ground.
 
Oscarpop said:
So I spent 4 hours this morning with a series of hammers and a gear puller trying to get my prop to loosen off its tapered shaft.

No joy.

Will start again tomorrow and will use a heat gun to heat up the prop to expand the metal.


Firstly, any suggestions as to how hot? Or is it just as hot as it gets?.

Second, any other suggestions?

I propose to tension the puller and then heat the prop. Hopefully the b#gger will pop off.
Click to expand...

I used a domestic blowlamp focussed on the prop boss and left there for maybe 10 minutes. No serious possibility of overheating with domestic kit.

The shaft was out of the boat of course. I'd already tried a propane torch at the boatyard as they recommended but I was too timid about holding it there for long enough whilst the shaft was in the boat.

Similar experience getting bushes out of a Norton gearbox - you have to heat way more than you initially feel you dare do.
 
Jack it off, two threaded rods screwed into tapped holes in prop hub. A solid bar square section across these and a central threaded bar, some heat. I've never used hammers, but leave the nut on to catch the prop.
 
Neil_Y said:
Jack it off, two threaded rods screwed into tapped holes in prop hub. A solid bar square section across these and a central threaded bar, some heat. I've never used hammers, but leave the nut on to catch the prop.
Click to expand...

He's already tried that and failed with the gear pullers. Hence the need for heat.
 
Well after a day of effing and jeffing, I now have a shiny new feathering prop in place :)

Tried the puller and tightened it until I thought the threads would pop.

Then tried blow torch, then a heat gun, then finally I heated the boss up using both.

No joy.

Finally I gave the back of the prop a couple of hefty whacks and the " note" of my strikes changed.

The rest was fairly easy.

Put the rope cutter back together , fitted the new prop then locktighted the lot.

Waited for high water after a very long hot shower and a good few lunchtime pints and it all seems to work fine.

Thank you all for your input. The prop needed far more heat than I would have thought.
 
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