Caraway
Well-Known Member
This is no time for having fun!
Failed to remove the shaft coupling
- Thread starter Boater On Thames
- Start date
Boater On Thames
Well-Known Member
@Croftie I am lucky to have your remind. Thank you! It actually should be 1.75 inches. I was using a mechanic calliper and it points to 45mm. Then after seeing your post, I purchased a digital calliper. I measured it again and again, it's actually between 44.3 to 44.5mm depends on the angle while holding the calliper. Plus I realized Americans usually using imperial size. So I eventually bought a 1-3/4 inches coupling. Hopefully, it's the right size.
@Caraway That's okay. I am going to do a lot more work for the boat after she back to the water. Such as fuel tank repair and interior remodel. So hopefully make her better ready for next season.
@Caraway That's okay. I am going to do a lot more work for the boat after she back to the water. Such as fuel tank repair and interior remodel. So hopefully make her better ready for next season.
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Flyingspanner
Well-Known Member
I think we will have a party when you successful remove it, even my missus who tends to role her eyes when I start to talk technical boating things has shown interest. I have been away working in Spain, and when I got home the second thing she said to me after hear is your updated jobs list was ‘has that chap got the thing of his shaft yet’ ??
John100156
Well-Known Member
But do remember, at the party the drinks are all on Lucas once he finally succeeds.
Then we will need to move on to the fuel tank repair
and interior remodelling.
I can see this thread going on for quite some time.....
Then we will need to move on to the fuel tank repair
and interior remodelling.
I can see this thread going on for quite some time.....
Croftie
Well-Known Member
Restoration man
Well-Known Member
Ive got to Applaud you for your Patience, I had same problem , straight shaft 2 grub screws but mine was clamp on type , heads rounded off in grub screw so drilled them out wouldn’t come off, spent 2 half days on it , turned out I hadn’t drilled all the grub screw out and that was what causing the problem, but it would have had the grinder on the third day for sure
Boater On Thames
Well-Known Member
I finally cut the coupling all the way through the keyway today, but it is still very tight. I am using my DIY steel plate puller with 6 bolts to pull it. It is now moving a little by little but very slow. I only manage to pull it around 1 cm after nearly 2 hours repeating tighten the 6 bolts again and again. I hammer it, no use. I heat it, no use. It just can not move faster. It still has around 14 cm to go! That will take forever! Nightmare!
I might need to cut through another side tomorrow to completely split it.
I might need to cut through another side tomorrow to completely split it.
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vas
Well-Known Member
No heat applied?
No need to cut all the way on the other side, half thickness and a few blows on a hefty chisel on the cut gap to open the thing!
Actually start with the chisel blows before doing anything else...
No need to cut all the way on the other side, half thickness and a few blows on a hefty chisel on the cut gap to open the thing!
Actually start with the chisel blows before doing anything else...
fisherman
Well-Known Member
Steady! Support the coupling on a hefty deadweight before hitting it sideways!
If you heat it you need to do it very quicky otherwise the shaft heats at the same rate and no advantage, get the outside hot before the shaft has a chance to catch up.
John100156
Well-Known Member
It is quite a thick flange so I would be cautious when using the chisel and heavy blows as it could damage bearings along the way, I understand the method and have used it myself but I would start cutting the other side (180) and as you get closer to the shaft, stop the metal thickness would be significantly reduced with more gaps to move, then gentle taps with a chisel the key side should open it up without damaging anything.
It will be interesting to see once off, why it was so heavily seized on, so we are all expecting some pictures....!
Or just persevere with bolts, moving it slowly, the more it moves off the shaft the less friction and it should speed up, hopefully....!
It will be interesting to see once off, why it was so heavily seized on, so we are all expecting some pictures....!
Or just persevere with bolts, moving it slowly, the more it moves off the shaft the less friction and it should speed up, hopefully....!
Boater On Thames
Well-Known Member
Exhausted! Finally got one coupling to come off from the shaft after 3 hours of trying today. Cut the keyway side all through, and another 180-degree side nearly all through (70% area through and scratch the shaft already). Then hammer it many many times to get it off. The key still sticking on the shaft, hammer it finally gets it off too.
The key was damaged, the 180-degree side shaft also got a cut scratch mark. But I think that it is not a big deal when using the new split-half coupling.
The key was damaged, the 180-degree side shaft also got a cut scratch mark. But I think that it is not a big deal when using the new split-half coupling.
Attachments
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Blue Sunray
Well-Known Member
Well done. any immediate indication as to why it was so difficulty, ie why they were so bound together?
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TheCoach
Well-Known Member
Well done Lucas, top marks for persevering 
cherod
N/A
cherod
N/A
tapered , no ?
Boater On Thames
Well-Known Member
Thanks.
Found no special structure. Just parallel shaft and parallel key. The coupling edge is 16mm thick. And I think it has never been removed in the last 29 years since it comes out from the factory.
Found no special structure. Just parallel shaft and parallel key. The coupling edge is 16mm thick. And I think it has never been removed in the last 29 years since it comes out from the factory.
burgundyben
Well-Known Member
Well done.
All suggests this was an interference fit, that was how the thrust is transferred. But thats bonkers, you could never assemble an interference fit like that in the boat, surely they didnt assemble that in a press, then fit it, then fit the engine.
I dont understand.
All suggests this was an interference fit, that was how the thrust is transferred. But thats bonkers, you could never assemble an interference fit like that in the boat, surely they didnt assemble that in a press, then fit it, then fit the engine.
I dont understand.
kashurst
Well-Known Member
I had a Princess 37 @ 20 years ago.. The shafts were replaced just before I bought it, age etc. A few years later I mangled a prop and the shaft on the tidal river Ouse near Goole.
It was a total pain in the arse to remove the coupling from the shaft. The mechanic at Newark marina got a welding torch on it after three days of trying ,on a "if it doesn't come off we will cut the shaft. " It did eventually come off, when it was bright orange hot! The coupling was later bored out to be a more sensible fit when the un- bent shaft came back. That was a parallel shaft and coupling.
Once back in the home marina a week or two later, chatting to the fitter who had replaced the original shaft, he told me they fitted it hot. i.e the coupling would only go on when it was heated to a very high temperature and then as it cooled it became an interference fit. Genius NOT! A few grub screws and/or a spring/roll pin would have been a lot easier.
Well done Lucas. Good luck with the other shaft.
It was a total pain in the arse to remove the coupling from the shaft. The mechanic at Newark marina got a welding torch on it after three days of trying ,on a "if it doesn't come off we will cut the shaft. " It did eventually come off, when it was bright orange hot! The coupling was later bored out to be a more sensible fit when the un- bent shaft came back. That was a parallel shaft and coupling.
Once back in the home marina a week or two later, chatting to the fitter who had replaced the original shaft, he told me they fitted it hot. i.e the coupling would only go on when it was heated to a very high temperature and then as it cooled it became an interference fit. Genius NOT! A few grub screws and/or a spring/roll pin would have been a lot easier.
Well done Lucas. Good luck with the other shaft.
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Caraway
Well-Known Member
It does seem a daft way to plan things.
Great effort in seeing it through to the end. I thought it was going to be a cutting job, but that is beyond reasonable.
I wonder if they got a shaft and coupling at the extreme ends of tolerances and ended up with the snuggest fit possible?
Not the best way to proceed. I've only once had a struggle assembling a component (output pinion on a Mini gearbox) and always regretted not sorting it before finishing.
Great effort in seeing it through to the end. I thought it was going to be a cutting job, but that is beyond reasonable.
I wonder if they got a shaft and coupling at the extreme ends of tolerances and ended up with the snuggest fit possible?
Not the best way to proceed. I've only once had a struggle assembling a component (output pinion on a Mini gearbox) and always regretted not sorting it before finishing.
fisherman
Well-Known Member
If only.... My shaft had a taper, nut and key both ends, so was reversible for wear, and a quick doink with hammer and deaweight got it off. It'ss all clamp couplings now and that's what I ended up with when i had a new shaft.
