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Frank

Shaft Coupling Glue

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I have a mate with a prop shaft coupling that is not sitting on a taper, just parallel shaft. It is on a key and locked with two grubscrews, not very good I suppose.

Anyway it is a bit loose so can anyone suggest some sort of Loctite or epoxy or something that he might use to remove the freeplay ? .

 

And by the way I have a saildrive :-)

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Not ideal but you could knurl the shaft then machine knurling to fit coupling. Another way would be to sleeve the coupling . I have seen this arrangement with grub screws before but it's better to thru bolt the shaft and coupling because in astern the only thing preventing the shaft from pulling out are the two grub screws Shaft exiting is a major event.

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Ideally if the shaft and prop bore could be measured then a good plan might be formed, or is the looseness only on the key? . Regardless the grubscrews if they must be kept on should seat in shallow dimples and be loctited (262 or 263)

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Not ideal but you could knurl the shaft then machine knurling to fit coupling. Another way would be to sleeve the coupling . I have seen this arrangement with grub screws before but it's better to thru bolt the shaft and coupling because in astern the only thing preventing the shaft from pulling out are the two grub screws Shaft exiting is a major event.

That is a very good point !!

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The coupling MUST be tight on the shaft. So the best/proper repair is to remove, re build and machine and refit.

Next idea is a special shim especially available for such a repair. Still needs removal and machining of shaft. 

 

Peen the shaft with a sharp center punch. Then locktite the coupling back on.

For jobs we engineers would call "temporary" or botch job, you can try peening the shaft with a centerpunch and then use locktite. There can be found some products especially made to build up loose shafts. But I have never found one to be completely perfect.

The key should never be "consumable". The coupling should be tight and for the key to wear means the shaft was not machine properly in the first place.

 

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Keyways and grubscrews are a  perfectly acceptable solution for a low hp setup. I would check the key as mentioned or just replace it, as for taking the slack out of it you can use loctite 660 or something similar. If its really sloppy then shim it.

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The coupling MUST be tight on the shaft. So the best/proper repair is to remove, re build and machine and refit.

 

For jobs we engineers would call "temporary" or botch job, you can try peening the shaft with a centerpunch and then use locktite. There can be found some products especially made to build up loose shafts. But I have never found one to be completely perfect.

 

The key should never be "consumable". The coupling should be tight and for the key to wear means the shaft was not machine properly in the first place.

 

I agree with your points about what is needed for a best/proper coupling Wheels, and also the context of temporary or botch jobs. When I describe the key as consumable, it would probably be better to state that if there is any slop or play, the key must be replaced asap, so that the slop or play does not exacerbate and flog out the whole arrangement (especially the key-way), resulting in a costly rebuild.

I certainly wouldn't intend for the key to need to be replaced regularly, because that indicates a serious problem with the coupling. The comment was more intended to communicate that keys are actually a cheap item that is simple to replace, and keeping the key in good order (snug fit) assists in stopping the whole coupling flogging itself out. Conversely, a worn key makes it very difficult to get a snug fit, even on a tapered shaft, and any wear on the key should be addressed asap.

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