Rudder link preferences

[ray schrauwen]

I've seen all sorts of rudder linkages on this forum and at ponds.

I am curious to this setup that for many moons has only been seen on Nitro boats etc.

it's doubled up with collars to keep them together.

What are people achieving with this? It looks more rigid.

Is it easier to bend the rod so it keeps it's shape?

Just looking to find out more about this style of push-rod setup.

[Fluid]

This allows using a threaded end on both ends of the linkage, and adjustability for any length. I have seen this for many years on gas boats, less on FEs.


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[ray schrauwen]

Cool, thanks.

[NativePaul]

My preference is for a short steel or carbon rod with ball links on both ends and an alloy servo horn, if only plastic horns are available for the servo a clevis has to be used as a ball link puts the force on one side of the arm and will twist a plastic one. If space or Cog restraints prevent me from doing that and I have to run a long or bent rod, I run a thin carbon rod through a series of carbon tubes glued to the hull that stop the rod from flexing.

The picture above shows a bad linkage made with little forethought, the twin rod and collet arrangement as Jay said allows for easy length adjustment, but that is all it has going for it, it is heavier than it needs to be, and needlessly introduces another point of failure, the bend in that particular one also makes it more flexible than it could be, I would guess that the servo mount was glued in before the rudder was fitted and definitely before the linkage was made, it looks like there is plenty of room available to mount the servo further to the left and angle it a little so a straight pushrod could be run.

By making things in a different order it would have been easy to make a linkage that didn't require the bend or need any adjustment at all. In my opinion the best way to install servos is first to fit the rudder where you want it then if you have limited posisitions to pot the hole like in this case you see if you can fit your servo in with a straight line between the arms and the servo parallel to that line, if so all is well and good, if not you take a file to the rudder mount so you can move the hole enough to do so. You then turn the radio on and centre the trims and fit the servo horn upright or slightly off upright if you want more travel one way than the other from the linkage for ovals, next place 2 flat an stiff pieces of material either side of the rudder hinge point and hold in place with elastic bands which will make the rudder spring to the centre. Now fit your links to the servo and rudder, and measure their height above the boat's floor, and drill the transom hole along the imaginary pushrod line, at a height that the pushrod is close to the top of the hole (as the pushrod drops when it moves away from centre), Nextput the servo in the boat and measure the length of the linkage, then cut the pushrod to size, fit the bellows to the hull (on the inside is neater and lasts longer as most bellows break down over time under UV light), pass the pushrod through the bellows and fit the end links. Next screw the end links to the servo and rudder arms. The last thing to do is glue in the servo mount, making sure that the pushrod passes through the top middle of the hole and the servo is parallel with the pushrod. This gives you the best linkage and the best chance of a trim free maiden voyage, while only taking a few minutes more than slapping everything together like in the OP's photo.

[srislash]

My preference is for a short steel or carbon rod with ball links on both ends and an alloy servo horn, if only plastic horns are available for the servo a clevis has to be used as a ball link puts the force on one side of the arm and will twist a plastic one. If space or Cog restraints prevent me from doing that and I have to run a long or bent rod, I run a thin carbon rod through a series of carbon tubes glued to the hull that stop the rod from flexing.

The picture above shows a bad linkage made with little forethought, the twin rod and collet arrangement as Jay said allows for easy length adjustment, but that is all it has going for it, it is heavier than it needs to be, and needlessly introduces another point of failure, the bend in that particular one also makes it more flexible than it could be, I would guess that the servo mount was glued in before the rudder was fitted and definitely before the linkage was made, it looks like there is plenty of room available to mount the servo further to the left and angle it a little so a straight pushrod could be run.

By making things in a different order it would have been easy to make a linkage that didn't require the bend or need any adjustment at all. In my opinion the best way to install servos is first to fit the rudder where you want it then if you have limited posisitions to pot the hole like in this case you see if you can fit your servo in with a straight line between the arms and the servo parallel to that line, if so all is well and good, if not you take a file to the rudder mount so you can move the hole enough to do so. You then turn the radio on and centre the trims and fit the servo horn upright or slightly off upright if you want more travel one way than the other from the linkage for ovals, next place 2 flat an stiff pieces of material either side of the rudder hinge point and hold in place with elastic bands which will make the rudder spring to the centre. Now fit your links to the servo and rudder, and measure their height above the boat's floor, and drill the transom hole along the imaginary pushrod line, at a height that the pushrod is close to the top of the hole (as the pushrod drops when it moves away from centre), Nextput the servo in the boat and measure the length of the linkage, then cut the pushrod to size, fit the bellows to the hull (on the inside is neater and lasts longer as most bellows break down over time under UV light), pass the pushrod through the bellows and fit the end links. Next screw the end links to the servo and rudder arms. The last thing to do is glue in the servo mount, making sure that the pushrod passes through the top middle of the hole and the servo is parallel with the pushrod. This gives you the best linkage and the best chance of a trim free maiden voyage, while only taking a few minutes more than slapping everything together like in the OP's photo.
Hey there Paul, do you glue the ball links to the carbon rod? I can't imagine any threading action on CF rod.
I am thinking of giving this a shot in my big Hydro.

[ray schrauwen]

Nice, thanks! Reading.

[NativePaul]

Yup, I glue them on to carbon rods. For big stuff you can get links that are designed to take carbon tubes, it depends how big big is.

[TheShaughnessy]

I also like to use ball links but, I just use a 440 rod and one of the collars with a set screw on the servo side. Ball links are easily replaceable so if it starts getting loose you can just slap a new one in.

[Shooter]

Here is what I use and it has worked very well. It is 3mm SS machinable stainless rod. Each end is threaded using a die. Ball cup and alloy horn on the servo end (like Paul stated), and a dubro pin clevis (drilled out using 2.5mm bit) on the rudder side. It has virtually no slop.

[longballlumber]

Here is what I use and it has worked very well. It is 3mm SS machinable stainless rod. Each end is threaded using a die. Ball cup and alloy horn on the servo end (like Paul stated), and a dubro pin clevis (drilled out using 2.5mm bit) on the rudder side. It has virtually no slop.

Be careful on the Alloy servo horn... Servo/servo gears become the failure mode in that system. just my 2 pennies