TECHNICAL SUPPORT
Published 2026-04-19
Adjusting theservotravel range—often called “endpoint adjustment” or “EPA”—is essential for ensuring your RC model’s control surfaces move correctly without binding or exceeding mechanical limits. This guide explains the precise, safe method to adjustservothrow on any standard RC transmitter and receiver setup, using common scenarios you’ll encounter in everyday flying practice.
When you install a new servo or replace a control horn, the default 100% travel from your transmitter may cause the pushrod to over-extend, leading to stripped gears, damaged hinges, or erratic flight behavior. For example, a typical aileron servo might try to move the surface past 45 degrees, but the wing’s hinge slot only allows 30 degrees. Without adjustment, the servo stalls, draws excess current, and may fail mid-flight.
A fully charged RC transmitter and receiver battery
The model securely placed on a stand with all control surfaces free to move
The servo connected to its intended channel (e.g., channel 1 for aileron, channel 2 for elevator)
Your transmitter’s manual for button/menu locations (general principles apply to all brands)
Step 1: Set your transmitter to the programming menu
Turn on the transmitter, then power the receiver. Navigate to the “End Point,” “Travel Adjust,” or “EPA” menu. On most transmitters, this is found under “Model Setup” or “Servo Setup.”
Step 2: Identify the channel and direction
Move the stick for the surface you want to adjust. Watch the servo arm rotate. For instance, move the elevator stick up – the servo arm should move in one direction. The display will typically show “UP” and “DOWN” endpoints separately.
Step 3: Adjust one endpoint at a time
Hold the stick fully in one direction (e.g., full up elevator).
While holding, increase or decrease the travel percentage value (usually 50% to 150% range).
Watch the control surface movement: increase until the surface reaches its maximum safe deflection – typically the point just before the hinge binds or the pushrod contacts the structure.
For a common foam park flyer, ailerons often need 80–90% travel; for a 3D aerobatic model, you might use 120–140% with longer servo arms.
Step 4: Repeat for the opposite direction
Move the stick fully the other way (full down elevator) and adjust the opposite endpoint using the same method.
Step 5: Verify with normal stick movement
Return the stick to center. Slowly move through full range. The surface should stop exactly at the mechanical limits on both sides without buzzing or straining the servo.
A typical intermediate pilot notices their aileron servo makes a loud buzzing sound at full stick deflection. Upon inspection, the aileron hinge binds at 35 degrees downward but the servo tries to push to 45 degrees. Solution: Enter the “Travel Adjust” menu for channel 1. Reduce the right-aileron endpoint from 100% to 78% (observed where binding stops). Then reduce the left-aileron endpoint to 79% for symmetry. The buzzing disappears, and the model rolls smoothly without overloading the servo.
Adjusting without mechanical setup first– Always center the servo arm (using sub-trim only if necessary) and set pushrod length so the control surface is neutral at 50% travel. Then adjust endpoints.
Setting endpoints too low– If travel is below 70%, you lose resolution and centering precision. Instead, move the pushrod to an outer hole on the servo arm or inner hole on the control horn.
Forgetting to save changes– After adjustment, exit the menu properly. Some transmitters require pressing “Save” or holding the menu button.
After replacing a servo with a different model (torque/speed differences may require new endpoints)
After changing pushrod geometry (new control horns or servo arm holes)
When switching between flight modes (e.g., low rates vs. high rates – note that endpoints are independent of dual rates)
After repairing a damaged control surface hinge
The servo’s mechanical travel must never exceed the airframe’s physical limits.Adjust endpoints so that at full stick deflection,the control surface stops just short of binding. This protects both your servo and your model, ensuring consistent, reliable flight performance.
1. Before your next flying day, go through each control surface (aileron, elevator, rudder) on your primary model.
2. Move the sticks slowly to full deflection while listening and watching for any strain or binding.
3. Reduce any endpoint that causes buzzing, and note the new percentage values in your model’s setup log.
4. Perform a pre-flight control check – surfaces should move smoothly and stop cleanly at maximum stick positions.
5. Re-check endpoints after any crash repair or servo replacement.
By following this method every time you set up a model, you will extend servo life, improve flight precision, and avoid unexpected in-flight failures.
Update Time：2026-04-19
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