Initial setting up/installation of the rudder servo

[Old School]

Is there a black art to setting up a rudder servo, please? If the servo is installed with the arm horizontal then as it translates full travel through its arc, the operating rod moves sideways. If the servo is installed with the arm vertical then the arm moves in a vertical deflection through the arc.

On my boat the arm will operate through a tube with a rubber bellows attached. With the arm at neutral rudder deflection should the arm be offset to one side of the tube and then as the arm travels either direction through its arc (rudder port or starboard) the arm will move to the opposite side of the tube. I hope this is self explanatory.

[Prodrvr]

I'm confused. What you do is, turn on the Tx, then the Rx. Have the servo horn removed from the servo. When it's powered up, the servo will center itself. Now center the rudder, then attach the servo horn onto the servo, attach and adjust linkage. Done.

[Old School]

I am referring to actually positioning the rudder servo in the first instance, i.e., no mounts installed in the hull. The operating rod not only moves fore and aft but also sideways if the operating arm is horizontal or vertically if the servo is installed on its side as in a clamp type mount. If one had a large hole in the transom then this sideways or vertical deflection would not matter, however, when the operating rod moves through a thinner tube in the transom then this deflection must be taken into accunt. I am not simply referring to setting up a servo when everything is already pre-installed.

[rol243]

yes as Prodrvr said. also when the rudder servo is set up with the rudder you can then go into your transmitter settings [ Rudder channel ] and [ Travel Adjustmet ] or [ end point adjustment ] of the servo arm so its not going too far in either direction . start with about 1 inch of travel in each direction and adjust after a water test run for more or less travel.

[Old School]

I am not referring to simply adjusting the servo once everything is already installed. My question relates directly to the exact position in the hull to mount the servo clamp mounting. The question has nothing to do with transmitters and receivers and rudder arm position to hook up the rudder. If one observes a rudder arm it does not move simply fore and aft, but sideways or vertically depending on how the servo is mounted. Because the servo arm operates through an arc then the rod position on the servo arm measured at 90 degrees to the servo will vary depending on its position in the arc. This causes the operating rod to deflect sideways or vertically depending on how the servo is mounted (arm horizontal or arm vertical) and it is this deflection that impacts on the position of the hole in the transom through which the operating rod moves.

[rol243]

mount the servo so its facing north / south with the arm on the side and at a vertical position 90 degree to the floor. when the servo is set up with the rudder rod the arm will push for rudder and pull for opposite rudder direction. very simple push and pull.

[Old School]

Next time you are operating your rudder look at how the rod exits the hole/tube in the transom. It is not a simple fore/aft movement. The rod will move sideways (laterally) if the servo arm is horizontal or vertically if the servo arm is mounted vertically (on the side of the servo). When the amount of deflection exceeds the internal diameter of the transom opening then obviously binding will occur. I need to physically mount the servo to minimise the impact of this deflection.

[rol243]

i can,t understand your issue here. the mounting of a rudder servo with its control arm vertical and attached is a pushrod which exits the transom and is then connected to a rudder arm, make the rudder move either left or right on your transmitters command. you don,t need much movement at the servo arm, have the transom pushrod hole atleast 1/4 inch diameter. there is no science to this very very simple fitting so just connect it all up and go boating.

[Prodrvr]

Yes, as the rod moves fore/aft, it does have some side to side movement. The side to side movement is minimal, and well within the limits of the inside opening of a standard rubber pushrod boot fitting. You really don't want the rudder to deflect more than 30 degrees.

[RayR]

linkage1a.JPG
You are correct, the pushrod moves in linear fashion inside the hole. For most boat application, you want the most servo movement providing the most torque through the 45 degree range of servo/radio wheel travel. As a rule of thumb use the inner most hole on the servo arm and the outermost hole on the rudder arm. This greatly reduces the huge "oversteer" problem with most RTR boats.

[Old School]

Many thanks gentlemen

[rol243]

i have some old Futaba and Kraft Linear servos that would suit your needs.

[Old School]

Many thanks, I have now sorted out the issue that I was having and will use the standard metal gear servo that I have.