If I may add to it, if I understand correctly, the set screws should not carry any load - it should be first, the friction between the coupling and the shaft (they should be perfectly mated), and second the key and the keyway.
One other thing: the set screws should be used only once. The second time around they don’t bite well enough into the shaft. The two set screws in the hole is a method used by the PSS dripless shaft seal. One set of set screws goes into the hole all the way and the second is tightened above them (to prevent them to undo). My $0.02 (I am not sure if it is worth that much, though) Marek 1994 C270 ”Legato” Ottawa, ON From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Jake Brodersen via CnC-List Sent: Tuesday, September 20, 2016 20:28 To: cnc-list@cnc-list.com Cc: Jake Brodersen <captain_j...@cox.net> Subject: Re: Stus-List Prop Shaft coupling Bill, I’ve had to separate the shaft from my coupling several times. It has always been an long, arduous process. I can’t imagine how it would ever work its way loose. The first time I had it apart, I even sanded the inside of the coupling to allow the shaft to slide back in place without too much effort. With you engine in forward gear, the prop should be trying to push the shaft into the coupler. Do you spend a lot of time in reverse? ;-) A deeper dimple might capture the set screws better. They should never come loose. I recommend Loctite blue. In this application, you could probably use the red variety. Applying some heat to the screws makes removal fairly easy, if it ever needs to be done. I agree with others that the root cause may be vibration. Pulling the shaft to check it would be prudent, if you’re into the project this far. Also, examine the prop for any abnormalities. Finally, how are the engine mounts, especially when the engine is under load? Excessive movement may exacerbate your coupling issue. My $.02 worth. Jake Jake Brodersen C&C 35 Mk-III “Midnight Mistress” Hampton VA From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of William Walker via CnC-List Sent: Tuesday, September 20, 2016 16:17 To: cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> Cc: wwadjo...@aol.com <mailto:wwadjo...@aol.com> Subject: Stus-List Prop Shaft coupling Some may remember that around mid summer I posted that my prop shaft had pulled out of coupling. Mine has two bolts which go through coupling and into small dimples drilled into shaft. They were wired in and over time the ends had worn off and allowed shaft to pull out when reversed was applied to prop. Some on list checked and had similar problems. I was surprised so many Well, on haul out I discover it has happened again, with the new bolts. Haven't pulled them yet to see, but shaft pulled enough to show key and the dimples, still in place. No excessive vibration or anything. Bolts still appear tight. Thinking maybe of going with two set screws in each hole, one snugged, another on top. Love to hear thoughts from listers with some experience. Bill Walker Evening Star CNC 36 Pentwater, Michigan
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