Feetech STS3215 Metal Servo Horns 25T, 6061 Aluminium Main + Rear Horn Set and 25T Arms, with Screws

These are anodised 6061-T6 aluminium servo horns with the 25-tooth 5.9 mm spline of Feetech STS3215, STS3250 and SCS servos: matched main and rear horn sets for SO-ARM101 joints, round 25 T output discs and 35 mm single-sided arms, all with mounting screws.

Replacement and upgrade horns for the STS3215 servos in SO-ARM101, LeKiwi and OpenDuck builds. The plastic horns supplied with cheaper servo lots strip under load; these anodised 6061 horns match the metal ones Hiwonder ships in its kits. Buy the 6-set to re-horn a whole arm.

What can you use it for?

• Replacing stripped plastic horns on cheap STS3215 lots
• Re-horning a whole SO-ARM101 arm (6-set)
• Building custom grippers, pan-tilt heads and linkages with the 35 mm arm
• LeKiwi and OpenDuck joints

Who is it for?

SO-101 builders who bought bare servos, and anyone whose kit shipped with plastic horns.

Compatibility

• Servos: Feetech STS3215, STS3250, STS3235, STS5420M, SCS20, SM40BL and other 25 T / 5.9 mm outputs
• Parts: SO-ARM100 / SO-ARM101 printed joints (main + rear horn), Hiwonder and Waveshare kits
• Screws: M2 horn screws and M3 centre screw included

Specifications

What's in the box

• STS3215 main + rear horn set with screws (1 servo): 1 × main horn, 1 × rear horn, screws
• STS3215 main + rear horn set × 6 (one arm): 6 × main horn, 6 × rear horn, screws
• 25T metal output horn (round, single): 1 × 25 T round horn with screws
• 25T metal arm 35 mm (single, colour random): 1 × 25 T 35 mm arm with screws (red or blue)

Frequently asked questions

Do I need the rear horn?

Yes for SO-101 joints: the printed link is clamped between the main horn on the output shaft and the free-turning rear horn on the servo's second shaft.

Will these fit the STS3250?

Yes, the STS3250 uses the same 25 T spline; only the mounting pattern of the servo body differs.