Another stripped thread, anyone local to Cuxton, Kent who could help me?

[Murv]

Long story short but last trip out I hit some semi submerged ironwork with rope on it.
The prop has come back from being repaired, I refitted it this morning but the allen bolt that holds the propeller nose cone in place won't insert properly.
It's a new bolt, the original was missing after the accident but I assumed it had just come unscrewed prior to that as I'd had the prop on and off a couple of times.
What I think has happened, is that when the rope wrapped around the prop, it's spun the nose cone which has ripped the bolt out and damaged the thread in the splined shaft.
I guess it's a simple retap job, but after my last thread it's not something for a beginner and I really don't want to risk causing further damage to the new outdrive.
Is there someone local to Cuxton, Kent who could help me? and by help, I really mean do it for me with me watching and providing tea/coffee...

Just to further complicate things, it's only accessible for around 3 Hours at low tide, but access is comfortable as it can be worked on from the tender.

Cheers,
Chris

 

[Firefly625]

Hi

In our workshop we often have stripped threads or seized studs etc that we have to deal with. The guys are pretty proficient at dealing with them, however sometimes when we can see it's going to be a lengthy job then it becomes far more cost efficient to sub contract and we have a local "thread doctor" that comes along and helps out. If you don't get a kindly volunteer here then I suggest you google you local thread doctor and give him a call.

Sorry I can't be of any real help apart from my suggestion!

 

[colhel]

It could ve something as simple as a bit of muck in the thread. Of course it also be a bit of rhe old bolt but simple things first, is there anyway if getting a high pressure jet of air or water up the thread?

 

[Murv]

Hi

In our workshop we often have stripped threads or seized studs etc that we have to deal with. The guys are pretty proficient at dealing with them, however sometimes when we can see it's going to be a lengthy job then it becomes far more cost efficient to sub contract and we have a local "thread doctor" that comes along and helps out. If you don't get a kindly volunteer here then I suggest you google you local thread doctor and give him a call.

Sorry I can't be of any real help apart from my suggestion!

A good suggestion, thank you. I hadn't even thought that someone could make a business out of it! the thread doctor is outside my area, but they will visit further afield for additional cost so if I don't have any luck I'll do that.

It could ve something as simple as a bit of muck in the thread. Of course it also be a bit of rhe old bolt but simple things first, is there anyway if getting a high pressure jet of air or water up the thread?

Not really, it just doesn't "feel right" though, the bolt almost rocks within the thread (hard to describe) and I'd cleaned it out thoroughly with Blue roll before I started so that the threadlock would stick. There was no sign of anything in there, I suspect it's remnants of the old bolt stuck in the threads.

If it really comes to it, is it just a matter of winding a tap and die set thingy in with a steady hand?

 

[colhel]

If it really comes to it, is it just a matter of winding a tap and die set thingy in with a steady hand?

Yes if the thread looks good. If there's a lot of load consider a heli-coil.
Also check you have the right bolt, I can only go on how you're describing it, but it does sound like a possibility.

 

[oldgit]

Presumably you already have the correct length replacement allan bolt. ???
There are a couple of different cone sizes for long and short hub props with different length bolts to match.
Shove a screwdriver into empty hole to gauge depth and compare with bolt you have.If the bolt you have will go in at least for 20mm into shaft threading should be sufficient to hold bolt in after you have tightened up cone.
Was bolt in there in the first place.???????
If somebody had over tightened allan bolt and it snapped off leaving the threaded bit in shaft.Nothing else is going to go in,
Is the replacement bolt the correct thread.You could always nip round to pirates cave buy a few longish bolts of assorted threads and see if one of them goes in cleanly.
In an emergency,ie I refused to pay VP inflated price,have used ordinary S/S bolt to secure cone.
It worked no problem with little locking washer.Also poke a bit of thin stiff wire into hole you should be able to "feel" if thread is there.If thread is absent head of bolt meebe is still in there.

 

[Murv]

Yes if the thread looks good. If there's a lot of load consider a heli-coil.
Also check you have the right bolt, I can only go on how you're describing it, but it does sound like a possibility.

Thanks for that, I'm not sure there's enough room to take it out for a helicoil, and I'm not keen to drill I must admit. Maybe cutting the original thread size will be enough to clean it up.
I'm fairly sure it's the right bolt, it came from Keyparts and starts off just fine in the thread. It's a few turns in that it starts locking up.
Maybe I'll order another one though, I guess it's quite possible the thread on the new one will be damaged now by my attempting to fit it.

 

[Murv]

Presumably you already have the correct lemgth replacement allan bolt. ???
There are a couple of different cone sizes for long and short hub props with different length bolts to match.
Shove a screwdriver into empty hole to gauge depth and compare with bolt you have.If the bolt you have will go in at least for 20mm into shaft threading should be sufficient to hold bolt in after you have tightened up cone.
Was bolt in there in the first place.???????
If somebody had over tightened allan bolt and it snapped off leaving the threaded bit in shaft.Nothing else is going to go in,
Is the replacement bolt the correct thread.You could always nip round to pirates cave buy a few longish bolts of assorted threads and see if one of them goes in cleanly.
In an emergency,ie I refused to pay VP inflated price,have used ordinary S/S bolt to secure cone.
It worked no problem with little locking washer.

There's a nasty thought, I wonder if the snapped off bolt is left in the bottom of the shaft??
As far as I know, the bolt and prop cone are the same for short and long hub props, just the extra room on the short hubs is taken up with the spacer. I may, of course, be wrong! but I'm fairly sure that's how it works.

It probably goes in 5mm or so, but certainly not 20mm.

 

[omega2]

5mm rather than 20mm? something is lurking in the hole!, probably the broken end of the old set bolt. Not familiar with VP I wish you luck.

 

[Murv]

5mm rather than 20mm? something is lurking in the hole!, probably the broken end of the old set bolt. Not familiar with VP I wish you luck.

Thank you, I suspect you're right. The more I think about it, the more suspiciously clean and short the thread looked when I cleaned it out this morning.
I'll get down and confirm at low tide tomorrow morning, but I think that's what it is.
If so, I'll have to cut the bolt down, seal it in with CT1 so that it can't unscrew (it's only to hold the propeller cone on the shaft) and then replace the shaft when the boat comes out in the Summer.

 

[omega2]

Why not take a small drill and a bolt extractor, one of those things that screw into the hole you make and operate reverse thread. If it only holds the cone on why bother just leave it off.

 

[rosssavage]

Or remove the broken bolt bit. Use a broken bolt extractor..

http://www.amazon.co.uk/TRIXES-Piec...id=1390073666&sr=8-11&keywords=bolt+extractor

Pedant mode: and stop calling it an allen (allan) bolt!! It's a cap head screw! Sorry, sorry, sorry......

 

[Murv]

Why not take a small drill and a bolt extractor, one of those things that screw into the hole you make and operate reverse thread. If it only holds the cone on why bother just leave it off.

Or remove the broken bolt bit. Use a broken bolt extractor..

http://www.amazon.co.uk/TRIXES-Piec...id=1390073666&sr=8-11&keywords=bolt+extractor

Pedant mode: and stop calling it an allen (allan) bolt!! It's a cap head screw! Sorry, sorry, sorry......

I've been pondering this all evening, and googling broken bolt extraction! Yes, I'll give it a go properly with some left handed drill bits first. The bolt was recently inserted, there's plenty of marine grease around it, it should come out relatively easily if I can get a hole started centrally.
It's hugely tempting just to leave the thing off, or bodge something in there. But, it must be needed, and knowing my luck the bloody prop will fall off just as a cargo ship is bearing down on me if I don't sort it out properly!

Incidentally, thanks for the correction re cap head screws, I've always wondered whether they were allen bolts/studs/screws!! now I know

 

[lynall]

If the bolt is stainless, be aware its a real barsteward to drill, especially if its any thickness.
My drive is later than yours, and its prop, the prop nut, metal lock tab and then the split pin, no cone, so maybe they did away with it for some reason?
What secures the prop nut when its all fitted?
Is it an anode?

 

[Murv]

I'm hoping to go in with a very small bit, and then a larger one that will remove the bolt. As above, it shouldn't be in under any pressure, unless the threads are damaged of course. That's the plan, anyway...
On mine, the prop sits on the splined shaft, the nose cone is thread, that screws down and holds the prop on. The cap head screw then prevents the cone from unscrewing.

 

[lynall]

Got it, so the cone is in effect the prop nut, with the cap head bolt as a securing device.
Hardest bit will be getting the first drill hole central.

 

[oldgit]

Suspect it is going to be virtually impossible to get your drill central with leg on boat.You may end up causing more damage.
Why not for now get that bolt as far in as you can and using washers to take up gap between cone and bolt head .
Even a couple of threads and dob of Locktite should prevent bolt from coming loose.
Cone holds the prop on !
Just check from time to time that bolt is still in situ.
If you are convinced that any bolt is left in shaft, may be quicker and cheaper to keep an eye out for s/hand shaft and just get someone to swap the lot over next time you come out for A/F etc.
Only two bolts hold assembly in gear case, its just getting the correct shimming on reassembly that matters.

 

[blobby47]

Hi All

In the past one of 280 legs on a dual leg set up had one leg with a cone retaining Allen screw and one with out( tab washer cone locking method) . I drilled and tapped spline shaft to suit what allen screw I had , so beware thread could be non standard try and ascertain what thread is actually in the shaft, try different thread set screws metric/imperial to check this,,
hope this helps
cheers bob

 

[oldgit]

" I drilled and tapped spline shaft to suit what allen screw I had , so beware thread could be non standard try and ascertain what thread is actually in the shaft, try different thread set screws metric/imperial to check this,,
hope this helps"


+1

 

[kashurst]

as per other posts trying to drill stainless steel is difficult at the best of times. I had a similar snapped bolt on part of an anchor windlass, (it was an M5 size -@ 5mm in diameter, recessed @ 5mm). I managed to get the snapped off part out by tapping it around with a small quality screwdriver and a hammer. If the bolt has snapped in situ the broken end will be quite rough and hopefully will give enough purchase if you hold the tip of the screwdriver at the edge of the bolt. The bolt is no longer under tension so there is only the friction of the thread keeping it in. If the bolt has recently been removed and put back with any grease on it you stand a very good chance of getting it out with patience. If you try and put in a spaced out new bolt into the damaged thread that is exposed at present, it won't hold properly and if it fails will make things worse.