Voron Belted Z Mod — Increase Your V0.2 Build Volume to 150mm³

Mod V0.2 Upgrade

The Belted Z mod is one of the most impactful upgrades you can make to a Voron V0.2 or V2.4. It replaces the traditional leadscrew-driven Z axis with a belt-driven system, eliminating common Z artifacts, increasing build height on the V0.2, and simplifying the entire Z drive mechanism. This guide covers everything: what Belted Z is, why you'd want it, the full parts list, step-by-step assembly, Klipper configuration, calibration, and a frank comparison of pros and cons. Last updated: May 2025.

Originally developed by the Voron community to address the limitations of leadscrew-based Z drives, the Belted Z mod has matured through several design iterations. For the V0.2, it's practically a must-have — it unlocks additional Z height that the stock leadscrew physically cannot provide. For the V2.4, it's an optional refinement that smooths out tall-print quality. We'll cover both use cases here.

What Is Belted Z — And How It Works

In a stock Voron V0.2, the Z axis uses a single leadscrew driven by a NEMA14 stepper motor through a flexible shaft coupler. The leadscrew threads into a brass nut mounted on the bed carriage, converting rotational motion into vertical movement. This is simple and reliable, but it has inherent limitations: leadscrew imperfections (bends, thread pitch errors, eccentricity) translate directly into Z banding on prints, and the leadscrew's physical length caps the maximum Z travel.

Belted Z replaces the leadscrew entirely. Instead, a GT2 timing belt connects the Z motor (relocated to the bottom frame extrusion) to a pulley system that raises and lowers the bed. The motor drives a belt loop anchored to the bed carriage — as the motor turns, the belt pulls the carriage up or down. This is mechanically identical to how the X and Y axes work on your Voron: belt-driven linear motion.

The key insight: a belt has no leadscrew artifact. There's no rotating threaded rod to be bent or eccentric. Belt motion is inherently smoother than leadscrew motion because the belt teeth engage with the pulley teeth in a continuous rolling contact rather than sliding friction. The trade-off is that belts have some compliance (stretch under load) that leadscrews don't, but in practice this is negligible for Z axis movement.

Advantages Over Stock Leadscrew Z

• No leadscrew artifacts: Bent or eccentric leadscrews produce visible horizontal banding on prints, especially on tall cylindrical parts. Belted Z completely eliminates this source of artifacts. If you've ever printed a calibration cube and seen lines at regular intervals matching the leadscrew pitch, you know the problem.
• No Z wobble: A bent leadscrew causes the bed to wobble slightly at the rotation frequency of the screw. On tall prints, this wobble creates a periodic wave on the surface (often called "leadscrew ghosting"). Belted Z has no rotational wobble because the belt doesn't rotate — it translates linearly.
• Smoother Z travel: Belt drives have lower friction and no stick-slip effect (the static-to-dynamic friction transition that causes micro-stuttering in leadscrew/nut interfaces). Z hops, bed meshing, and layer changes are faster and quieter.
• Easier to build and maintain: No leadscrew alignment required, no flexible coupler to tighten, no Z nut to lubricate. The belt system is simpler to install and requires less ongoing maintenance than a leadscrew.
• Quieter operation: Belt drives are inherently quieter than leadscrews. The difference is noticeable: a Belted Z V0.2 at 10mm/s Z travel is significantly quieter than a stock leadscrew V0.2 at the same speed.

Belted Z for Voron V0.2 — Increasing Build Volume

The V0.2's stock build volume is 120mm in Z. This is limited by the stock leadscrew length and the motor location at the top of the Z extrusion. The Belted Z mod repositions the Z motor to the bottom of the frame, freeing up the entire extrusion length for travel. With a Belted Z mod, the V0.2 can achieve 150mm or even 160mm of Z travel — a 25-33% increase in build height.

This is the single most compelling reason to install Belted Z on a V0.2. That extra 30mm of Z height transforms what you can print: from small cosmetic parts and trinkets to functional prints like keyboard cases, Raspberry Pi cases, drone frames, and compact enclosures. Combined with a removable top hat mod, some V0.2 builds push 170mm+ of Z travel.

The mod also simplifies motor placement. The stock V0.2 has the Z motor mounted awkwardly at the top of the left rear Z extrusion, with the leadscrew running down inside the frame. Belted Z moves the motor to the bottom, where it's easier to access, cooler (away from the hot chamber top), and doesn't protrude above the frame — making it easier to build a top hat or enclosure extension.

Belted Z for Voron V2.4 — Smoother Tall Prints

The V2.4 uses four leadscrews (one per Z corner) driven by four independent stepper motors with a Z tilt correction system. While this provides excellent bed leveling and rigid support, the leadscrew artifacts are still present — especially on very tall prints (250mm+). Each leadscrew can have its own eccentricity and pitch errors, and Z tilt correction can only compensate for gross leveling errors, not per-revolution leadscrew artifacts.

Belted Z on the V2.4 replaces all four leadscrews with a belt system (usually two belts driven by two motors, or a single belt driven by one motor with a belt-synchronized arrangement). The result: no leadscrew banding on tall cylindrical prints, smoother Z travel for the heavy V2.4 gantry, and quieter operation. The V2.4 Belted Z mod is less common than the V0.2 version, but users who print tall vases, mechanical parts, or architectural models report visibly cleaner surfaces.

One consideration: the V2.4's bed is much heavier than the V0.2's, so the belt system needs to handle higher static and dynamic loads. Most V2.4 Belted Z designs use wider belts (6mm or 9mm GT2) and stronger motors (NEMA17 48mm). Backlash (belt slack) is more of a concern on the heavy V2.4 bed, requiring careful tensioning and, in some designs, a counterweight or gas spring assist for the Z lift.

Parts Required

Printed Parts

• Modified gantry / X carriage mounts: The parts that connect the belt to the bed carriage. For V0.2, these replace the brass nut mount on the bed carriage. For V2.4, they replace the leadscrew nut mounts on the four bed corners.
• Z motor mounts: Brackets that hold the NEMA14 (V0.2) or NEMA17 (V2.4) motor at the bottom of the Z extrusion. These must be printed in ABS or ASA — do not use PLA as chamber temperatures will soften it.
• Idler pulley mounts: Brackets at the top of the Z extrusion that guide the belt return path. Usually includes the 20-tooth GT2 idler pulley.
• Tensioner block: A sliding block with a captive M3 screw used to tension the Z belt. Similar to the X/Y belt tensioners on the V0.2.
• Cable guide: Optional but recommended — keeps the Z motor wires organized along the extrusion.

Print all parts in ABS or ASA at 0.2mm layer height, 4 perimeters, 40% infill. The motor mount and tensioner block experience the highest mechanical loads — use 5 perimeters and 50% infill for these. No supports are required for most Belted Z designs if oriented correctly. STL files are available on the Voron User Mods GitHub (search "V0.2 Belted Z" or "V2.4 Belted Z").

Hardware Required (V0.2 Variant)

• 2x F623-2RS flanged bearings (for idler pulleys at top of Z extrusion)
• 1x GT2 timing belt, 6mm wide, 360-400mm closed loop (pre-measure your frame; the exact length depends on your build and whether you use a top hat)
• 2x GT2 pulleys, 20-tooth, 5mm bore (one for motor shaft, one as idler)
• 1x NEMA14 stepper motor (same as stock V0.2 Z motor, or upgrade to a 36-40mm length for more holding torque)
• M3 x 8mm, 12mm, 16mm, 20mm BHCS and SHCS screws (qty: ~20-30 depending on design)
• M3 heat-set inserts (qty: ~8-12)
• M3 x 20mm set screw or shoulder screw (for tensioner)
• 2x M3 nuts (for belt anchor points)
• Optional: 1x M5 x 30mm screw + M5 nut (for tensioner block, if design uses M5)

Assembly Walkthrough

Step 1: Remove the Stock Z Drive

On the V0.2, remove the Z motor from its mount at the top of the left rear Z extrusion. Disconnect the motor wires. Remove the flexible coupler and the leadscrew. Unscrew the brass nut from the bed carriage. On the V2.4, repeat this for all four corners. Keep the stock hardware in a labeled bag in case you ever want to revert.

Step 2: Install the Motor Mount

Mount the NEMA14 motor to the printed motor mount at the bottom of the Z extrusion. Use M3x8mm screws through the motor flange into heat-set inserts in the printed mount. The motor shaft should point upward. For the V0.2, the motor goes on the left rear Z extrusion. Route the motor wires downward and out through the bottom of the printer — they should not interfere with the bed's downward travel.

Step 3: Install the Idler Pulleys at the Top

Mount the F623-2RS flanged bearings in the idler pulley brackets at the top of the Z extrusion. Secure with M3x16mm screw through the bearing center. The flange should face outward to guide the belt. For the V0.2, this goes at the top of the same extrusion as the motor mount, directly above the motor. The belt path is: motor pulley -> up to top idler -> down to bed carriage anchor -> back to tensioner -> down to motor pulley.

Step 4: Install the Belt

Loop the GT2 belt around the motor pulley and the top idler pulley. Thread the belt through the bed carriage belt anchor points. The belt should form a closed loop with the bed carriage attached to one side of the belt loop. Most designs use a "fixed anchor" on one side of the carriage and a tensioner on the other. Do NOT tension the belt yet — leave it loose for now.

Step 5: Anchor the Belt to the Carriage

Insert the belt ends into the printed belt anchor blocks on the bed carriage. Use M3 screws and nuts to clamp the belt. The belt teeth should engage with matching features in the printed part (a toothed clamp surface). Ensure the belt is oriented with the teeth facing inward toward the clamp surface. Tighten both anchors evenly.

Step 6: Tension the Z Belt

Adjust the tensioner screw to apply tension to the belt. The target tension is 30-40 Hz measured with a smartphone frequency analyzer app (like "Gates Carbon Drive Tension" or any guitar tuner app). Pluck the belt like a guitar string and adjust until the fundamental frequency reads 30-40 Hz. For the lighter V0.2 bed, aim for 30-35 Hz. For the heavier V2.4 bed, 35-40 Hz. Too loose: Z banding from belt slack, poor first layer consistency. Too tight: increased motor load, bearing wear, and potential belt skipping.

A note on tensioning: the Z belt is much shorter than the X or Y belts, so the frequency will be higher for the same tension. A 35 Hz Z belt is normal. Use the FORCE_MOVE command in Klipper to move the Z axis up and down a few times, then re-check the tension — the belt may seat into the pulley teeth and loosen slightly.

Klipper Configuration

The primary configuration change for Belted Z is the rotational_distance parameter. With a leadscrew, this is the leadscrew pitch (e.g., 4mm for a standard V0.2 leadscrew). With a belt drive, it's calculated from the motor pulley tooth count and belt pitch.

[stepper_z]
step_pin: Z_STEP
dir_pin: Z_DIR
enable_pin: !Z_EN
microsteps: 16
rotation_distance: 40         ; 20-tooth pulley * 2mm GT2 belt pitch = 40mm
full_steps_per_rotation: 200  ; Standard NEMA14/NEMA17
endstop_pin: ^!Z_STOP         ; Your Z endstop pin (unchanged)
position_endstop: 0.0
position_max: 150             ; Updated for increased Z height on V0.2
position_min: -5              ; Allow slightly negative for probe calibration
    

rotation_distance = pulley tooth count x belt pitch. For a 20-tooth GT2 pulley (2mm pitch): 20 x 2 = 40mm. If you use a 16-tooth pulley: 16 x 2 = 32mm. Verify this is correct by commanding a 100mm Z move and measuring the actual travel with a caliper.

position_max: Set this to your new maximum Z height. For a V0.2 Belted Z, this is typically 150-160mm. Measure physically: home Z, raise to the maximum safe position (before the bed carriage contacts the top of the frame), and record the height. Add 2-3mm of safety margin.

Z endstop: The Belted Z mod does not change your Z endstop wiring. If you use a probe (Tap, Klicky, inductive), the endstop pin mapping and virtual endstop configuration remain the same as stock. If you use a physical Z endstop switch on the frame, verify it triggers at the correct height with the new belt travel.

Calibration

Z Steps / Rotation Distance Verification

After configuring rotation_distance, verify accuracy: home Z, then use FORCE_MOVE Z=100 SPEED=5 to move 100mm. Measure the actual movement with digital calipers (measure from the bed surface to a fixed reference point on the gantry). If it's not exactly 100mm, adjust rotation_distance proportionally: new rotation_distance = old value x (actual mm / 100mm). Repeat until accuracy is within 0.05mm over 100mm.

Z Belt Tension Equalization

For V2.4 Belted Z builds (multiple belts), each belt must have equal tension to prevent the bed from tilting under load. Use the frequency method described above to tune each belt to within 1-2 Hz of each other. After tensioning, move the Z axis through its full range and re-check — the belts may settle differently.

First Layer and Bed Mesh

Run a full bed mesh after the Belted Z installation. The belt drive may introduce a different bed tram pattern than the leadscrew system. Use BED_MESH_CALIBRATE and visually inspect the mesh for unusual peaks or valleys. If the mesh shows a consistent tilt, run Z_TILT_ADJUST (V2.4) or SCREWS_TILT_CALCULATE (V0.2) to re-level the bed. Run a single-layer test print (100x100mm square, 0.2mm height) and verify uniform extrusion across the full bed.

Belted Z vs Tri-Z — Comparison

The Tri-Z mod is an alternative to Belted Z that uses three independent belts (one for each Z corner on triangular-bed Vorons like the Trident) or three belts on a V2.4's four-corner bed. Tri-Z provides independent Z control per corner, eliminating the need for mechanical Z tilt adjustment — each motor is simply commanded to the correct height.

• Belted Z: Single belt (V0.2) or dual belt (V2.4) with mechanical synchronization. Simpler electronics (fewer stepper drivers). Lower cost. Easier to configure (no per-motor Z tilt calibration). However, the belts are mechanically coupled — any tension imbalance translates to bed tilt that must be corrected mechanically.
• Tri-Z: Independent belt per corner with individual stepper motors. More complex electronics (requires additional stepper drivers on the mainboard). More expensive (additional motors, drivers, wiring). More configurable (Z_TILT_ADJUST compensates for any mechanical misalignment digitally). Better for extremely precise leveling on large printers.

For the V0.2, Belted Z is the clear winner — simpler, cheaper, and the single-bed design doesn't benefit from multi-motor Z. For the V2.4, Tri-Z offers more precise leveling at higher cost and complexity. Most V2.4 users are satisfied with Belted Z; Tri-Z is for those chasing the absolute best Z accuracy on tall prints.

Pros and Cons Summary

Pros

• Eliminates leadscrew banding artifacts completely
• Increases V0.2 Z height by 25-33% (120mm -> 150mm+)
• Smoother, quieter Z movement
• Simpler mechanical alignment during build
• No leadscrew lubrication needed
• Lower parts count and cost than leadscrew replacement on V0.2

Cons

• Backlash: Belts have some slack (backlash) that leadscrews do not. On Z, backlash means the bed may drop slightly when the motor direction reverses (e.g., during Z hop). In practice, this is minimal on well-tensioned belts (under 0.01mm at 35 Hz tension). However, if you print parts that require precise Z reversal (like threads or overhangs with Z hop), the backlash can be noticeable.
• Less position holding under load: A leadscrew is self-locking — when the motor stops, the thread friction prevents the nut from moving. A belt is not self-locking; the bed is held in position solely by the motor's holding torque and the belt tension. If the motor loses power, the bed can drop. This is a safety consideration: ensure your printer has power-loss recovery and consider adding a mechanical brake or counterweight if you print very heavy parts (500g+).
• Belt stretch over time: GT2 belts can stretch slowly with use, changing the Z calibration. Re-check Z belt tension every 3-6 months. Leadscrews don't stretch.
• Requires printed parts: You must print the Belted Z parts in ABS/ASA before you can install the mod. If you only have one printer and it's your V0.2, you'll need to commission prints from someone else or use a filament that can survive chamber temperatures.

Overall, the pros heavily outweigh the cons for most users. The backlash concern is overblown — at proper belt tension, Z backlash is below the threshold that affects print quality. The position-holding concern matters only for very heavy prints or printers that lose power frequently. For the V0.2 in particular, the Belted Z mod is transformative and highly recommended.