Bushing #3713 and Gear #10928: Sizing Shafts and Gears Correctly
By Circuit Cubes | Tenka Inc. | Published: 2026-10-17
Category: Tips & Care
Learn how to properly size shafts and gears using Bushing #3713 and Gear #10928 for secure, wobble-free Circuit Cubes builds.
Quick Answer
If a shaft wobbles or a gear slips, the fix is often a correctly sized bushing or gear. Bushing #3713 provides a snug fit for standard shafts, while Gear #10928 (8 teeth) offers a precise mesh for small builds. Choose the part that matches your shaft diameter and gear train needs.
Why Shaft and Gear Sizing Matters
In Circuit Cubes builds, a loose shaft or mismatched gear can cause wobble, poor power transfer, and unexpected stops. The shaft diameter and gear bore must match exactly to keep motion smooth. Even a small gap leads to friction or slipping that drains battery life and reduces torque.
Bushing #3713 and Gear #10928 are two small parts that solve common fit problems. The bushing acts as a spacer or bearing surface to center a shaft, while the 8-tooth gear provides a compact drive option for tight spaces. Using them together or separately ensures your build runs reliably.
Diagnosing Fit Issues
If your motor spins but the wheel doesn't move, or if the gear rattles on the shaft, you likely have a sizing mismatch. Check the shaft diameter first. A bushing like #3713 fills the gap between a smaller shaft and a larger hole, stabilizing the connection. For gear trains, an 8-tooth gear (#10928) meshes best with other small gears; using a larger gear with a small pinion can cause binding.
Inspect the parts for wear or debris. A clean, dry fit is essential. If the gear still slips after cleaning, the bore may be too large for the shaft—try adding a bushing or selecting a gear with a smaller bore.
Diagnosis: Shaft and Gear Fit Check
- Symptom: Shaft spins freely inside the gear or wheel; build wobbles or fails to move. Check for a gap between shaft and bore.
- Likely Cause: Shaft diameter is smaller than the gear bore, or the bushing is missing or worn. A bushing like #3713 can fill the gap.
- Corrective Action: Slide Bushing #3713 onto the shaft before attaching the gear. If the gear still slips, replace it with Gear #10928 which has a compatible bore size for standard shafts. Test the assembly by hand; it should rotate without play.
- When to Stop or Choose Another Option: If the bushing and gear still do not fit snugly, the shaft may be non-standard or damaged. Consider replacing the shaft or using a different gear size from your parts collection. Do not force parts—this can damage the motor or cube.
Key Parts for Correct Sizing
- Bushing - #3713: Bushing #3713 is a replacement part from Circuit Cubes | Tenka Inc., offered as a single unit for use with compatible builds and assemblies. Use this bushing to reduce shaft play and center rotating parts, preventing wobble and ensuring smooth power transfer.
- Gear - 8 Teeth - #10928: Gear - 8 Teeth - #10928 is a replacement part from Circuit Cubes | Tenka Inc. It is listed in the Parts category and is intended for use with compatible builds. The 8-tooth gear is ideal for compact gear trains where space is limited. Its small size allows for higher speed ratios but requires precise alignment to avoid skipping.
