Autopilot arm on rudder post

[carlo de leo]

Originally Posted by foufou

If the post is hollow and you drill through that doubles the area of contact of the bolt. If you add a compression tube inside the post then you can tighten the bolt more so long as you don't approach breaking. And of course use tefgel or other anti corrosion product and nylock nut

Liked that. Maybe adding a solid aluminum profile piece inside the shaft.
Thanks

[UNCIVILIZED]

Originally Posted by carlo de leo

Yes, its a set screw. But already has a little hole for it to set (more Than a dimple) and this hole/dimple was stripped.

How about adding a Helicoil to the hole so that a threaded fastener can be refitted?

And FYI, you can edit your posts for up to 1/2hr after first posting them. Either to add info to them, or to edit for readability, etc.

[SeaSon]

Don't over think this.
A. The hole in the post is so you don't warp the hollow pipe, deforming it and making rudder removal difficult.
B. Drill and Tap the arm to install a larger set screw, or drill and tap both on just the one side for a stainless bolt.
C. If bolt, get it long enough to add a nut under the head to lock the pieces tight.

[carlo de leo]

Originally Posted by UNCIVILIZED

How about adding a Helicoil to the hole so that a threaded fastener can be refitted?

And FYI, you can edit your posts for up to 1/2hr after first posting them. Either to add info to them, or to edit for readability, etc.

Thanks,
I think the wall thickness is not enough for a helicoil, but i'm gonna have this veryfied.
And I'm sorry for any mistyping or inaccurate words, I'm just a brazilian fan of this forum.

[DeepFrz]

carlo de leo, you did just fine. It's a good thread. The only thing that would have helped to clarify the situation would have been a picture of the rudder post/arm rather than a drawing.

[FutureStories]

Originally Posted by UNCIVILIZED

Not quite sure on this, my bleeping swear jar's almost always full, so for f**k's sake, what use is it then? It's too packed to use to hold anything else.

My swear jar finances all my upgrades!

[Cadence]

Originally Posted by DeepFrz

carlo de leo, you did just fine. It's a good thread. The only thing that would have helped to clarify the situation would have been a picture of the rudder post/arm rather than a drawing.

I'm with DeepFrz don't worry about the English. It's my first and only language and you do as well as me.

A pic would be great. Best of luck.

[Capella]

If both the post and arm are aluminium, I am assuming a small boat with small loads.....

The only way to get this right is to employ a professional engineer, who knows how to calculate stresses in metals. That is bound to cost a bit though. When I had my autopilot fitted (on a 10-tonne cruiser), I had an engineer build a somewhat over-strength contraption that should never fail due to stresses placed on the rudder by the steering mechanism, autopilot ram, or water on the rudder.

Note that the rudder requires stops to prevent it ripping the ram to pieces if the rudder gets forced over hard by a wave! (Or, heaven forbid, Mother Earth.)

To get back to the specifics of your problem, I would recommend inserting a solid filler inside the post, to allow the through-bolt that you are going to install to replace the "big screw" to be tightened without deforming the post. Note that a slight local deforming might not be too bad - it will prevent slippage - but that should not extend to the part of the post inside the bearings that keep the ocean out. The filler can be wood or metal, as long as it is a tight fit.

If you really want to go to town, you can drill a hole through the post, and install a pipe to act as a sleeve for the bolt. (How good is your aluminium welding?) The outside of the pipe transfers stress to the post (which is better than having the bolt do it, since the diameter of the pipe is larger than that of the bolt). Just select a pipe with an inner diameter exactly the same as the diameter of the through-bolt, and a nice thick wall. (You can drill out the pipe to the exact diameter if required.) You will have to shape the ends to match the rounding of the post.

The screws squeezing the arm onto the post are not good engineering. They should exist only to keep the two pieces of the arm together (I assume something similar on the other side of the arm as well?) The arm should be locked on to the post by positive means, like a key (not possible with a hollow shaft) or a through-bolt as described. Friction will fail!

Lastly, if space permits, I would put in a second through-bolt. Just to make it stronger.....

Regards
Michael

[UNCIVILIZED]

Originally Posted by FutureStories

My swear jar finances all my upgrades!

Mine helps me with useful things like women, & booze. Which, women & liquor help me to bulid up my swear jar. In theory at least. Since liquor helps me to forget that I have one, as well as where it is, & what it's for.
I'm convinced that somehow, I'm either doing something very, very wrong, or very, very right

[Neptune's Gear]

There are plenty of hollow shafts with keyways. Depends on shaft dia and wall thickness.

[carlo de leo]

Hello again!
Thread Updates

Inicial Problem: tiller arm was sliding on rudder post

Decision taken: rebuild the actual one piece tiller arm into a two-pieces part. Lock pin through one wall of the rudder post

Still in doubt: rigger says it's utmost importance anodize the tiller arm (aluminum). I don't see the need.
Picture attached is the two-pieces part recently rebuild, not the old one.

[Sailmonkey]

Originally Posted by carlo de leo

Hello again!
Thread Updates

Inicial Problem: tiller arm was sliding on rudder post

Decision taken: rebuild the actual one piece tiller arm into a two-pieces part. Lock pin through one wall of the rudder post

Still in doubt: rigger says it's utmost importance anodize the tiller arm (aluminum). I don't see the need.
Picture attached is the two-pieces part recently rebuild, not the old one.

looks good!

I wouldn't anodize, maybe spray yearly with boeshield though.

[carlo de leo]

Originally Posted by Sailmonkey

looks good!

I wouldn't anodize, maybe spray yearly with boeshield though.

Thanks Sailmonkey!

[Cadence]

I can't imagine a rudder shaft being an aluminum tube! A solid SS shaft is my preference.

[carlo de leo]

Originally Posted by Cadence

I can't imagine a rudder shaft being an aluminum tube! A solid SS shaft is my preference.

I was mistaken when I said The shaft was aluminum, actualy, is SS. I thought I had already correct that. Sorry.
Tube Wall widht is 8mm. Shaft daimeter 60mm. Boat has 38 feet.