V-Slot Wheels & Bearings

Keep Your Carriage Running Smooth

V-slot wheels are the rolling contact point between your printer's carriage and its aluminum extrusion frame. On printers like the Ender 3, CR-10, and Artillery series — which use 2020 and 2040 V-slot extrusion profiles — these small POM plastic wheels bear the full load of carriage and bed movement across thousands of print hours. They are a wear item with a predictable lifespan, and worn wheels are one of the most commonly overlooked causes of print artifacts that look like loose belts or Z-banding.

How V-Slot Wheels Wear

POM wheels develop flat spots from prolonged contact pressure at rest positions — visible as a rhythmic thudding or vibration as the carriage moves. Over time, the V-groove profile also wears down, reducing the contact area with the extrusion rail and introducing lateral play into the carriage. This play translates directly into layer inconsistency, subtle ghosting, and dimensional inaccuracy that tightening the eccentric nuts can no longer correct. Fresh wheels restore the tight, smooth carriage movement the printer had when new.

Eccentric Nuts — The Tension Adjustment

Eccentric nuts allow the wheel-to-rail preload to be adjusted by rotating an offset nut that moves the wheel mounting point closer to or further from the extrusion. Correct preload means the carriage rolls smoothly with no lateral play but no binding. Eccentric nuts themselves can wear or round off over time, making precise adjustment difficult — replacing them alongside the wheels is a straightforward and inexpensive step.

Bearings — 625ZZ & 695ZZ

V-slot wheels run on small radial bearings — most commonly 625ZZ (5×16×5mm) and 695ZZ (5×13×4mm) depending on the wheel design. These bearings can be replaced independently when they develop roughness or noise without replacing the entire wheel assembly. Keeping a set of spare bearings costs almost nothing and eliminates the most common cause of grinding sounds from the carriage.

Signs It Is Time to Replace Your Wheels

Replace V-slot wheels when you notice rhythmic thudding during carriage movement, visible flat spots or cracks on the wheel surface, excessive lateral play that eccentric nut adjustment cannot eliminate, or grinding and roughness that persists after lubrication. Under regular use, inspect every 6–12 months and replace as a set rather than individually.

Related Parts

V-slot wheels are part of the broader motion system — for XY movement, also check your belts & pulleys. For Z-axis precision, see motion parts including lead screws & anti-backlash nuts. For high-performance builds moving beyond V-slot, see linear rails. Back to the full 3D Printer Parts & Accessories guide.