Cutless bearing set screws

[pbuck100]

The yard has the tool which allows the cutless bearing to be replaced on my 1980's Hunter 31.
However, the mechanic says he cannot get the allen head set screws out (I think he rounded the allen head faces off) and so now must remove the shaft. Now the job is much bigger and involves separating the shaft and flange, and dropping the rudder which means employing the lift to raise the stern since the rudder shaft is too long to allow removal of the rudder. Then drilling out and retapping for new set screws and repacking the stuffing box (not a bad idea anyway).
The mechanic says he cannot drill the set screws out with the shaft in place for fear of nicking the shaft.
It seems to me there must be more ways he can try to remove the screws before he takes the boat apart. PB Blaster overnight maybe or one of those screw removal tools. Also there's the thickness of the bearing to drill through before any drill would reach the shaft.
Does anyone have any ideas I could suggest to him?

 

[Witzend]

yea, drill'em out, but calculate the depth and put a drill stop collar on the bit to prevent any damage to the shaft.

 

[Tim R.]

You certainly have more options before removing the shaft. If the allen screw is already rounded I would do this:

- Ensure that all paint is removed from around the screw
- Soak for 24 hours in PB blaster
- Use a reverse drill bit to drill out the screw. Slightly larger size than the allen key hole. The heat from the bit may be enough to break it loose and the reverse direction should back it out before drilling through but you are right about the bearing shielding the shaft from getting nicked.
- If that does not work, try an "easy-out" or similar.

 

[tommays]

A 135 deg split point bit should be flat enough to get through the screw and unless you get crazy the most you would do is put a tiny drill spot on the shaft

Your going to get plenty of warning when you hit rubber

 

[pbuck100]

Thanks everybody for the inputs.
However, it just struck me that if he manages to remove the set screws and the bearing, will there be enough room between the end of the hole and the shaft to get a tap to do its job? Could he for instance go as far as possible, and then if not enough thread cutting occurred, break the end of the tap off in a vise and try a second pass with the shortened tap?
Also I think I've read that the set screws are a backup method of stopping the bearing rotating, with the tight press fit being the primary method and that they rarely actually do anything. Could I get away without any set screws at all?

 

[Allan12210]

A blind tap is flat on the end and is used for tapping to the bottom of blind holes. That should work fine. I would still use set screws. After the new cutless bearing is installed, just dimple through the hole with a punch ever so slightly so the set screws end up in the dimple. install the screws with some lock-tite where they just contact the bearing sleeve. You don't want them so tight that they distort the bearing.

 

[wetass]

I would think that if you can get the set screws out, there wouldn't be a need for the tap - would there?

 

[Rich Stidger]

Re-tap after the bearing is out. Use a blind hole tap and even then you should have at least 3/8" between the inside of the strut and the shaft. Plenty of room for a tap. Push the shaft away from the set screw hole and against the strut.

 

[pbuck100]

"I would think that if you can get the set screws out, there wouldn't be a need for the tap - would there?"

Yes you're right, unless they're drilled out.
It would be great if a no-drill solution worked.

 

[bria46]

Go and buy a set of Easy-Out bits before you try anything else. Loctite makes a "freeze" application in a can. Both are available at many automotive stores. Use some bolt loosener too.

 

[Steve Dion]

Extractor? I would think that a yard would know how to do this without the additional labor.

http://www.amazon.com/Damaged-Screw-Extractor-Remover-Tool/dp/B001TLIJU2

 

[tommays]

Once you have rounded a set screw the easy-out is fail as the depth is to shallow

As soon as the screw was hard to move it was heat time

 

[Roger Long]

The mechanic says he cannot drill the set screws out with the shaft in place for fear of nicking the shaft.

Translation: He can't drill the screws out without a drastic reduction in the size of the final bill.

Ask him if he has a reverse drill set. If not, get a new mechanic. You may have to fight with the yard about this if he's their employee but you shouldn't have to pay for a shaft removal over this unless there is more to the story than we're hearing. There is a lot of metal between the ends of those set screws and the shaft and it's easy to drill and tap for the next larger size of set screw if he buggers up the holes.

 

[kloudie1]

I definitely agree with the left handed drill bit idea.. I keep a set in my box for exactly that reason.. and he has plenty room to work the re-tap if necessary.. Good luck..

 

[bria46]

DON'T HEAT IT FREEZE IT! www.loctitefreezeandrelease.com/

 

[Witzend]

Beware, one of the things that might happen if you drill out the set screws that happened to me on my frozen coupling is that the end of the set screw will detach from the threaded shank and start to spin while drilling it out. You then make the assumption I have drilled it out and inadvertently leave the tip still in place. The problem is, that when you start to press out the bearing the tip gets jammed between the shell of the bearing and the strut casing. Once that occures it's probably hopelessly jammed and you would then need to remove the shaft anyway. Make sure you have a clean hole righ down to the bearing shell before you try to press it out.

 

[RON20406]

Pbuck, I would first try some form of easy out/reverse drill bit with the aid of PB Blaster as recommended by others. If that doesnt work, Witzend's advice was very good with the precaution of breaking the tip off between the shaft and the bearing. I have sailed my boat happily over 16,000 miles without set screws in my shaft housing/strut. If the bearing was pressed properly, the set screws are probably unnecessary. Good luck and good sailing, Ron

 

[pbuck100]

Success (partial)!
I drilled out the set screws and retapped and replaced sucessfully (thanks everybody). The old bearing is out now and the new bearing in - I rented a hydraulic bearing press and did it myself..
However, a brand new problem: the new bearing went in too easily - I didn't even need the hydraulic press, I could push it in with just a 1" washer behind it and my thumbs pushing on the washer....and also without the set screws tightened the bearing rotates in the strut along with the shaft! There is no discernible play between the bearing and the strut - just not a press fit (obviously).

Of course, I don't want the bearing to work its way out of the strut at some inconvenient time and so would would want something else besides the set screws holding it in. I have noticed that Loctite makes some products specifically for this (bearing mount products).

Are these good? Waterproof? Should I (can I) get a bearing with an OD a few thou larger?

 

[Allan12210]

Not sure they make the bearings larger by a couple of thou. One trick we used to do was to knurl the inside of the bore, but since you can't do that, then you can try the following. Use a center punch (one of the spring loaded ones would be best), and pop a bunch of little divots on the surface of the bearing. Not so much to distort the shape but enough to pooch out the surface around the dimple. This will increase the diameter enough to get a better press fit. You can only do it once...if you take it out again, you will have to punch new dimples, so do a bunch. Once the set screws are back in (and make sure to dimple where they sit) it should load the whole thing enough that it won't move. I have used this method for the wheel bearings on my car where the race did not fit tightly into the rotor. It worked fine and never spun the bearing race.

Since the shaft is really gliding over the rubber surface of the cutless bearing supported by a boundary layer of water it should not be providing any large rotational forces on the bearing. Keep the zincs about 6 inches away so there is plenty of water being pumped into the bearing and have your diver keep an eye on it for you for peace of mind. I used the red loctite on the set screws only and some silicone grease on the bearing so I can press it out again easily next time.

Allan

 

[MitchM]

what a great thread! i sure learned a lot about how to get stuck screws out...

did 'the yard' supply you with the cutless bearing you used ? are you sure the yard supplied the correct diameter of cutless bearing for your shaft size? measure your shaft diameter and check out the cutless bearing sizing info at a major online cutless bearing dealer like deepblue yacht supply. if the same incompetent yard supplied your cutless bearing as wanted to drop your rudder, etc. -- i'd suspect a misfit of your cutless bearing size to your shaft.

i was recently faced with a local mechanic who claimed
he couldn't remove my prop or cutless bearing ,'becuase they were metric'.... i bought the tools and did it myself...