Wire tied set screw for prop shaft flange

Apr 5, 2009
1,655
Catalina '88 C30 tr/bs Oak Harbor, WA
I always hear that I should wire tie the set screw for prop shaft flange but none of the set screws I can find have a hole in them. No problem thinks I. I have a drill press and a brand new cobalt bit. It did not even put a scratch in it!?!?!?
Where do you get set screw with a hole in the head for the wire????
 
Jan 4, 2006
3,989
Hunter 310 West Vancouver, B.C.
I have a drill press and a brand new cobalt bit. It did not even put a scratch in it!?!?!?
That's what you get for being so obsessive about the job :biggrin:.

The square head set screws you got are most likely the more expensive hardened steel variety. Perfect for inner races on ball bearings but not so much for our shaft flanges. What you're after is unhardened carbon steel set screws with an oval or flat tip. Not SS or the flange suffers in that environment.

I tried to find drilled heads a number of years ago with no luck. What I found was the set screw I wanted but in lots of 100. If you get the unhardened variety, you can easily drill the holes (with a new bit). The flanges rely on the shaft key to prevent rotation so the set screw need only be light duty to prevent axial motion.
 
Apr 5, 2009
1,655
Catalina '88 C30 tr/bs Oak Harbor, WA
That's what you get for being so obsessive about the job :biggrin:...
To be honest, for the past 8 years I have not had a tied set screw and didn't worry about it. Just put some locktite and forgot about it...

But then there was that post this year from the guy who almost sank his boat when the prop and shaft pulled out of his boat one fine afternoons. :yikes:
 
Nov 22, 2011
984
Ericson 26-2 San Pedro, CA
To be honest, for the past 8 years I have not had a tied set screw and didn't worry about it. Just put some locktite and forgot about it...

But then there was that post this year from the guy who almost sank his boat when the prop and shaft pulled out of his boat one fine afternoons. :yikes:
How about adding a shaft collar on the exposed part of the shaft, in between the coupler and the stuffing box, so the shaft can't slide out?
 

capta

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Jun 4, 2009
4,320
Pearson 530 Admiralty Bay, Bequia SVG
Any prop shop or a machinist who works on shafts will have many in stock, on the work benches and the floor.
The wire itself isn't meant to stop a bolt from loosening, but it will alert a conscientious boat owner to a coming problem.
 
Jan 11, 2014
7,993
Sabre 362 113 Fair Haven, NY
So many solutions.

The set screw should be pointed and there is often an indent in the shaft for the set screw to set. The purpose of the set screw is to back up the key in the key way.

To keep a shaft from sliding out, something needs to be attached to the shaft to keep it from going out the shaft log. A sacrificial anode close to the strut will do. A polished SS split shaft collar between the flange and the shaft log is the classy solution. A lowly hose clamp will also work.

If you ever have to take the flange off, replace it with a new split flange. The next person who removes the flange will appreciate it. The next person might be you. The split flange does not need a set screw. The clamping pressure of the flange and the keyway keep the shaft turning with the transmission.
 
Apr 5, 2009
1,655
Catalina '88 C30 tr/bs Oak Harbor, WA
...If you ever have to take the flange off, replace it with a new split flange. The next person who removes the flange will appreciate it. The next person might be you. The split flange does not need a set screw. The clamping pressure of the flange and the keyway keep the shaft turning with the transmission.
This is a split flange on a replacement shaft that was fitted, faced and dimpled by a prop/shaft shop in 2014. Even though it is a split flange, it still has the set screw and dimple.
 
Jan 4, 2006
3,989
Hunter 310 West Vancouver, B.C.
How about adding a shaft collar on the exposed part of the shaft, in between the coupler and the stuffing box, so the shaft can't slide out?
And as an added bonus, it howls like a banshee if it ever contacts the gland nut to let you know that something's just not right :yikes: ! ! !

But you're right, it's better than losing the whole shaft out the hole. That's where the wired set screws come in, to prevent axial movement.
 
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Likes: Hayden Watson
Dec 25, 2000
5,104
Hunter Passage 42 Shelter Bay, WA
The wire itself isn't meant to stop a bolt from loosening,
Uuh, yes it does. Worked on jet engines for a few years and many of the fasteners required lock wire to prevent them from becoming loose, which could result in engine failure. Vibration over time has an effect on a secure fastener. The coupler on our boat has a fastener on each side with a small hole drilled in the head for the main purpose of a lock wire to prevent the fastener from becoming loose, which can have serious consequences. Install the lock wire in such way that places clockwise pressure on the fastener followed by several tight twists, then bending over the cut end to avoid snags or flesh cuts.
 
Nov 6, 2006
9,247
Hunter 34 Mandeville Louisiana
If ya really want to drill the head of a hardened bolt (carbon steel), heat the head with a torch until it is glowing bright red all over the head, then let it slowly air cool away from any drafts or blowing air. Once it cools off, it will be soft enough to drill.. after drilling, you can re-harden it by heating again to bright glowing red and then quickly quenching in water.. Not recommending that you do that..
 
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Likes: jssailem
Apr 5, 2009
1,655
Catalina '88 C30 tr/bs Oak Harbor, WA
I am thinking that I will just install Loctite red. It will need to be heated if I ever want to remove it but that is doable.
 
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Likes: jssailem
Jan 4, 2006
3,989
Hunter 310 West Vancouver, B.C.
If ya really want to drill the head of a hardened bolt (carbon steel), heat the head with a torch until it is glowing bright red all over the head, then let it slowly air cool away from any drafts or blowing air.
Exactly. You've obviously done this before.

It's called annealing. I always wondered if I missed anything important in that lecture I slept through on that sunny Friday afternoon:cuss:. Maybe.
 
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Likes: kloudie1
May 7, 2012
986
Hunter e33 Maple Bay, BC
I am thinking that I will just install Loctite red. It will need to be heated if I ever want to remove it but that is doable.
Not necessarily. It is my understanding that the holding strength of Loctite in general varies with the substrate used on. This link shows a less than 50% strength when Loctite Red (271) is used on stainless steel as compared to steel.

Loctite 271 - TDS
 
Apr 5, 2009
1,655
Catalina '88 C30 tr/bs Oak Harbor, WA
Not necessarily. It is my understanding that the holding strength of Loctite in general varies with the substrate used on. This link shows a less than 50% strength when Loctite Red (271) is used on stainless steel as compared to steel.

Loctite 271 - TDS
The flange coupling is cast steel and the set screw is some type of hardened steel with an electroplating. Neither are stainless.