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Cannot tighten tiller to rudder shaft


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Hi

There is some play between the tiller and the rudder shaft on my Cav 32. The tiller appears to have been acquired from another boat at some stage and looks as though it is made for a shaft of slightly larger circumference . The key does prevent the tiller turning far but there is still 2 or 3 degrees of play when the tiller is turned. The pinch bolts are tight but the ends of the tiller head appear to clamp together before reasonable pressure is applied to the shaft.
I think it might help if the gap where the clamp ends meet is enlarged by a mm or 2. Is there a DIY way to do this? Hacksaw? Angle grinder? Or any other ideas? I think it is bronze. 

Thanks

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Is the key narrower than the slot in the tiller arm? The key should be tight, and prevent horizontal movement. The clamp should stop the tiller falling off is all. 

 

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I had this problem on my cav, but it was between shaft and rudder.  If the problem is the key not fitting the keyway I have a zero cost solution that was still working when I sold the boat 20,000 miles later.

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Thank you for your responses. Just to clarify a bit further, the clamp does not tighten enough even to hold on to the shaft. There is a large nut that screws on that stops the tiller lifting off and when I removed the nut today I was able to wiggle the tiller off without even loosening the pinch bolts.

The key did appear to fit snug when I pushed it into both the tiller and the shaft slot but it is possible that there is some wear from the constant movement though. Perhaps the key or the slot is not as square as it once was. Hard to measure properly without precise tools. What was your keyway fix BP?

So, it is possible there is some wear in the key. It is definite that it doesn’t clamp tightly. Is there any product where a strip of something could be wrapped around the shaft to increase the size and improve the friction hold (like wet and dry sand paper or liquid gasket)? 

 

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I’ve just reread my previous comment and I realise that of course there must be some movement in the key or nothing would move. I suspect it might be twisting in the slot though as it did feel like the width was reasonably tight.

So 2 problems - it doesn’t clamp tightly and the key has some play in it. 

 

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I had 3 different engineers try to make a key that wouldn't  slip. No go. Something wrong in the design they said. In frustration I mixed a hot batch of pure epoxy( no powder) and poured it in. Hard enough to hold it for the next 7 years, brittle enough to remove with a tap from a hammer.

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It’s definitely the key in the tiller as I can see the tiller move independently of the shaft. Probably the slack in the clamp has caused the key to wear a bit which causes more movement in the tiller and more wear in the key etc. I like the sound of the epoxy. I will try that. My worry though is that if I can’t get the clamp tighter then it will put undue pressure on the key again and I’ll be in the same position soon.. 

If there is a way to increase the cut/gap where the ends of the tiller clamp meet I think that will help. Currently the ends of the clamp touch before any significant pressure can be passed to the shaft.

It’s not a huge problem - been like it for the 3 years I’ve owned it but nevertheless it is annoying so I’m keen to sort it.

Thanks

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Try clamping it in a vice and run a hacksaw through it

but don’t over tighten the vice

Maybe a new key but epoxy also sounds good  

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Had a similar thing on my Cav 32 and the pinch bolt had sheared. Had to drill it out and replace. Couldn't figure out why I had so much play all of a sudden.

Was an easy fix.

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It is probably due to wear, due to a small movement over time. The Key should be tight, but it is not there to prevent movement as such. That is the job of the clamping pressure. The key "selects'' the tiller position on the shaft and is a lock only second. But if the tiller slops around for any time, that will wear both shaft, clamp and key and it only takes a slightly small amount of wear to feel really lose.
The idea with this is that the clamping pressure would normally have been enough. But the wear now means not enough clamping pressure is obtained.
          Two ways to go about it. The first is the easy way, although there needs to be caution. If there is only a very little amount of clearance between clamp and shaft, then slicing that gap will work. But if that clearance has become too great, then the clamp will never mate to the shaft surface true enough. Try is the only way you will know. The caution part is that you don't want to have too much play, as pulling that clamp together will put stress on the opposing side to the slot and you could cause it too crack. Only you are going to be able to judge that. Fortunately, Bronze has a bit of movement before fracture. Much more than Brass. So you should be OK.
The next stage, if it is too much of a gap to pull th clamp up without over stressing it, you would need to remove the tiller, take to an engineer and have a sleeve made up to slip over the shaft and the tiller clamp bored enough to slip over the sleeve. Rudder shaft can be left in place and don't worry about the Key, unless it is sloppy and falls out all the time. But ss you can imagine, that way is not going to be cheap. So have a go at slicing the gap a little and try clamping it a little more first.
The top Nut holds the Tiller down on the shaft. Be aware the shaft and rudder could drop with all that removed.
When refitting, pull tiller down with top nut till firm, but do not tighten too much till the clamp has been pulled in tight. Then fully tighten top nut. Check there is no up/down play in the shaft-rudder. That bearing surface needs to be clean and a slight smear of a good waterproof grease on the surface helps. It's one of those areas that no one ever thinks about cleaning and lubricating, untill is all gets worn.

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20 minutes ago, harrytom said:

maybe replace key 1st. 2nd go to a model shop and buy some thin brass sheet and use as a shim,last resort cut the slot in clamp.

Totally.  Reversable if you get it wrong, relatively cheap and easy and permanent if you get it right.

https://www.trademe.co.nz/a/marketplace/building-renovation/tools/hand-tools/measuring/listing/3459853267

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Awesome ideas everyone - thank you.

I will look at brass shims first before cutting the gap as plan B. Plan C is the rebore and sleeve (unless I can find a 2nd hand one that fits better).

Are keys something that can be bought off the shelf or are they made to order?

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19 minutes ago, Jonh said:

Awesome ideas everyone - thank you.

I will look at brass shims first before cutting the gap as plan B. Plan C is the rebore and sleeve (unless I can find a 2nd hand one that fits better).

Are keys something that can be bought off the shelf or are they made to order?

Try Henley propellers on the shore,be a starting point. or buy a bit of brass and file down 6mm square??

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look for an old school engineering supplier Jon - places that sell belts pullies and drive systems for industrial equipment would be a good place to start and save time.  If you can get a decent gauge to measure the keyway, great.  If not, take the clamp and the existing key with you.  Its more important that the key matches the keyway in the shaft rather than the tiller

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Be aware that brass shim material will quickly dezincify. You may slow that by applying a thin film of grease or lanocote. But very thin. You don't want the film to end up making the clamp lose again.
If it were me, I would simply slice a shimy off the two sides of the clamp and tighten. A Grinder with a thin 1.6mm cut off disc is all you would need. Run it up the gap and see if that allows it to bolt tight. As I said above, the Key itself is not doing much. It is there to align the tiller to correct oriantation to the rudder. And besides, if the key is square, you could simply turn it one side, or if it is a flat key, then smack it with a hammer against a piece of metal and spread it out a little. It takes very little. Clean the edges with a file and tap it back in place.

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