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Chapter 06 — Z axis (and Chapter 06b — Gantry squaring)

One page per step

Read this chapter one step per page — big pictures, prev/next, and the same tick marks. This page is the whole chapter in one scroll.

Hangs the finished gantry on the four Z joints, belts all four Z corners, and gets the gantry roughly square to the frame — after which the machine can move in Z. Part B (Ch 06b) is the real gantry squaring and cannot be done here: it needs motor control, so it runs out of the middle of Chapter 13 (Step 13.34), cold; the hot lock-in is Ch 14's.

What you're building in this chapter. Four Z joints — one at each corner of the gantry — and the four Z belts that hang the gantry from them. A Z joint is a pair of printed blocks: the z_joint_lower bolts to the ball-bearing carriage riding the Z rail on an upright, the z_joint_upper (the Z bearing block) bolts under the gantry corner, a front idler or A/B drive, and clamps the belt's first end beneath it, and one M5×40 bolt joins the two. The belt's second end clamps on top of the same corner, under the blue upper clip fitted in Ch 05. Each corner's belt runs from that joint down to the Z drive at the bottom of the upright, around its pulley, up to the Z idler at the top, and back to the joint — so turning one drive raises one corner, and four of them together lift and level the gantry. Part A gets all of that built, the gantry lifted into the frame, and the machine roughly square. Part B is the real squaring, and it needs a running printer, so it runs from inside Ch 13 (Step 13.34) — cold and with the machine open. The heat soak and the hot lock-in follow in Ch 14, once the panels are on.

Revali reading a caliper
Four corners agreeing on one height. Get this right and every print remembers it.

Time: 3.5–5.0 h hands-on for Part A, first build (survey §7.2). Part B adds ~1 h hands-on, cold (the heat soak and hot lock-in now live in Ch 14).

Sessions: 9 × ~30 min (first-build estimate — 8 in Part A, 1 in Part B, which is deliberately unbroken; each Pause: line carries its own segment minutes).

Prerequisites:

  • Ch 02 — Z drives, Z idlers, Z rails, deck. Four Z drives built and bolted in, four Z idlers at the tops of the uprights, four MGN9 Z rails on the uprights with their carriages on, 16T/20T pulley stack verified, set screws threadlocked (survey §5.2 W12). The deck panel is in.
  • Ch 05 — Gantry. Complete gantry: X and Y extrusions, XY joints, X carriage, titanium backers already fitted (survey §5.2 W2 — backers after this point means a teardown). Left off the printer, as the manual leaves it at p.106–107.
  • Print batch B05 — Z joints + Z chain (docs/voron-print-plan.md §3 B05). Black ASA, 1 plate, 6.4 h.
  • Print batch B02 — the single blue accent session, which carries the four lower Z belt clips and the Z chain retainer brackets. The four upper clips went on in Ch 05 (Steps 05.19–05.23).
  • Heat-set inserts already done for every part in both batches (survey §5.2 W3).

Tools

  • Hex 2.5 mm, 3 mm and 4 mm; a ball-end 4 mm helps at the Z joints
  • Hex 2.5 mm, 3 mm and 4 mm for Part B
  • Two people for the gantry lift (survey §7.3, chapter 06 row) — Alex on one side, daughter on the other
  • Four rubber rail stoppers taken off the Z rails (the LDO trick, below), or long zip ties as the fallback
  • Needle-nose pliers or tweezers for belt routing (manual p.118)
  • Steel rule / tape for cutting belt; flush cutters
  • Part B only: 150 mm machinist square (DIN 875/2), digital caliper, 150 mm rule, phone with Spectroid (Android) / Sound Spectrum Analysis (iOS) / Gates Carbon Drive

Consumables: small zip ties ×4 (belt tails), long zip ties ×4 (only if you skip the rail-stopper trick), masking tape and marker.

Printed parts

Parts arrive in the bins named below (see the bin map in print/README.md#bins); check the bin label's list before you start.

Looks like STL Bin Repo path Qty Colour Batch
z_joint_lower_x4.stl 06-Z-joints Voron-2 STLs/Gantry/Z_Joints/ 4 Black B05
z_joint_upper_x4.stl 06-Z-joints Voron-2 STLs/Gantry/Z_Joints/ 4 Black B05
[a]_z_belt_clip_lower_x4.stl 06-Z-joints Voron-2 STLs/Gantry/ 4 Blue B02
[a]_z_belt_clip_upper_x4.stl 05-XY Voron-2 STLs/Gantry/ 4 Blue B02 — fitted in Ch 05 (p.91, p.93, p.95); loaded at Step 06.20
z_chain_bottom_anchor.stl 10-chains Voron-2 STLs/Gantry/ 1 Black B05 — fitted in Ch 10 (manual p.201–203)
z_chain_guide.stl 10-chains Voron-2 STLs/Gantry/ 1 Black B05 — fitted in Ch 10 (manual p.201–203)
[a]_z_chain_retainer_bracket_x2.stl 10-chains Voron-2 STLs/Gantry/AB_Drive_Units/ 2 Blue B02 — fitted in Ch 10 (manual p.204)
z_rail_stop_x4.stl 02-Z0 · 02-Z1 · 02-Z2 · 02-Z3 LDOVoron2 STLs/ 4 Black B05 — optional rail-end safety stop, fitted at Step 02.10
— z_joint_upper_hall_effect.stl — Voron-2 STLs/Gantry/Z_Joints/ 0 — SKIP per LDO — no hall-effect endstops in this kit, not printed

Hardware (chapter totals — Part A)

Fastener / part Qty Note
M5 hex nut 4 one per Z bearing block, manual p.110
M3×30 SHCS 4 one per corner; passes through block → lower clip → front idler or A/B drive → the reserved rail-slot T-nut (Step 05.14), p.111
M5×30 BHCS 4 one per corner, same stack, p.111. The second belt end clamps under the Ch 05 M5×16 pair instead
M3×20 SHCS 16 four per z_joint_lower into the MGN9 carriage, p.115
M5×40 SHCS 4 one per Z joint, up from the lower joint into the block's M5 nut, p.115
Gates open belt, 2GT, 9 mm 4 × ~1400 mm (manual minimum ≥1200 mm) manual p.111 minimum for the 350; the kit ships 6 m of 9 mm belt, so 4 × 1400 mm leaves ~400 mm spare for a mis-cut (LDO 350 Rev D BOM)
6×3 mm magnet 0 hall-effect option only — not used
Zip tie, 3×150 mm (belt tails) 4 manual p.120
Zip tie, long (gantry support) 0–4 only if you skip the rubber-rail-stopper trick
Rubber rail stopper — from the Z rails 4 taken off the Z rails and re-fitted mid-rail — LDO note p.114–116

Read first

  • Do manual p.115–116 before p.114. LDO: "We recommend completing steps on page 115-116 then use the rubber rail stopper under the Z joints mid rail. This will allow you to set the Gantry on page 114 on the joints without the need for long zipties." Fit the four lower Z joints and park them at a known height first, then lower the gantry onto them. src
  • Ignore every hall-effect option on p.110 and p.113. LDO note p.145: "SKIP The kit does not use hall effect endstops." Four plain z_joint_upper_x4, no 6×3 magnets, no z_joint_upper_hall_effect.stl. The XY endstop on this kit is the D2F PCB pod fitted in Ch 05. src
  • The gantry lift is a two-person step and the manual says so (p.114: "An extra pair of hands helps with this step"). Nobody holds a 350 gantry one-handed while fishing for an M5×40.
  • The gantry alignment on p.122 is not the gantry squaring. p.122 gets the gantry square enough to belt. The real procedure (Part B) starts by fully releasing A/B belt tension and dropping the lower Z joints, so it has to come after firmware is up. Ch 07's A/B tension is provisional, and so is Part B's (survey §5.2 W1, §4.4 #2). A/B tension is set three times on purpose: Ch 07 (provisional — enough to home and QGL), Ch 06b Step 06b.15 (provisional again, after squaring, machine cold and open) and Ch 14 Step 14.4 (final — panels on, machine cold, door open, immediately before the closed-chamber soak and hot Z-joint tighten of Step 14.6). Z belts: Ch 06b Step 06b.3 (so QGL converges for squaring), set for the last time at Ch 14 Step 14.5, in the same cold session.
  • Belt tension targets: Z belts 140 Hz over a 150 mm span measured from the Z idler centres; A/B belts 110 Hz over a 150 mm span. Both from docs.vorondesign.com. voronldo.com's 80–100 Hz (A/B) and 110–130 Hz (Z) numbers are discarded — survey §4.3.
  • A Z carriage that runs off the end of its rail is a ruined carriage. The balls fall out. Keep the printed z_rail_stop_x4 (batch B05) at the top of each rail, or keep a hand on the carriage.

Sources for this chapter:

Video coverage (Steve Builds, pre-release LDO kit — differs from Rev D+): Part 4 @0:12:41 (+18m), Part 4 @0:55:52 (+32m), Part 4 @1:30:00 (+14m), Part 5 @0:46:00 (+14m), Part 5 @1:03:16 (+10m), Part 6 @1:34:40 (+2m), Part 9 @2:49:00 (+5m)

Part A — Chapter 06: Z axis (mechanical)

Manual p.108–123. Nothing in this part needs power.

Step 06.1 — Confirm the starting state

What you're looking at: The frame before the gantry goes in: a Z drive at each bottom corner, a Z idler at the top of each upright, and a Z rail with a carriage on each upright. Those four carriages carry the whole gantry.

Parts: none.

Do: Confirm: four Z drives bolted in; four Z idlers with tensioners at the upright tops; four MGN9 Z rails on the second holes from each end, carriages on and greased; the gantry on the bench with its titanium backers on.

check Check

Every Z carriage slides its full rail by hand, smooth, with no notchiness or gritty spots. Fix a rail that fights you now.

Source: Voron manual p.108

Step 06.2 — Learn the four names

What you're looking at: One corner, top to bottom: the Z idler at the top of the upright, the Z joint that carries the gantry corner where the belt clamps, the Z belt, and the Z drive at the bottom. Four of these lift and level the gantry.

Parts: none.

Do: Learn the stack at one corner: Z drive at the bottom, Z joint above it, Z belt between them, Z idler at the top. Both belt ends clamp at the gantry corner, one under it, one on top.

check Check

You can point at all four features on the real machine at the front-left corner before you build the other three.

Source: Voron manual p.109 · Video: Part 4 @0:55:46

Step 06.3 — Seat an M5 nut in each Z bearing block

What you're looking at: The look-alike pair. The z_joint_upper, the Z bearing block, clamps the first belt end and takes the M5 nut. The z_joint_lower bolts to the Z carriage; one M5×40 joins the two into a Z joint. The lower is chunkier, with four M3 holes.

Parts:

  • z_joint_upper_x4 ×4
  • M5 hex nut ×4

Do: Press one M5 hex nut fully into the pocket of each of the four z_joint_upper blocks, square and flush. Push it home with the flat of a screwdriver, never by threading a bolt through and cranking.

check Check

The nut is flat, hex faces aligned with the pocket walls, and clear thread shows through the bore from the far side.

Caution

Rev D+ / LDO: Do not fit the 6×3 mm magnet shown on this page. It belongs to the hall-effect endstop build. LDO note p.145: "SKIP The kit does not use hall effect endstops." All four blocks are the plain z_joint_upper_x4. src

Source: Voron manual p.110 · LDO Build Notes § Voron 2.4 build FAQ

Step 06.4 — Cut the four Z belts

What you're looking at: Open-ended GT2 belt off the reel. This is the 9 mm belt for Z; the A/B belts in Ch 07 are the narrower 6 mm. Each is one cut length, not a loop: both ends clamp at one gantry corner, below and on top.

Parts:

  • consumable: Gates 2GT open belt, 9 mm wide, four lengths of about 1400 mm
  • consumable: masking tape

Do: Cut four lengths of ~1400 mm. The manual's minimum for a 350 is 1200 mm and the kit supplies 6 m, so 1400 leaves ~400 mm spare. Cut square with flush cutters, between teeth. Label each with masking tape.

Check

Four belts, all the same length within a few mm, all with clean square ends and no frayed cords.

Source: Voron manual p.111

Good stopping point · ~30 min since the last one

M5 nuts seated in all four Z bearing blocks, four Z belts cut to length and labelled by corner. Do not start clipping a belt end in: each corner is one continuous clip-and-clamp job.

Step 06.5 — Lay the first belt end under the gantry corner

What you're looking at: The first belt end goes onto the serrated pad under a gantry corner, a front idler or A/B drive, facing up while the gantry is upside down. Teeth down, the belt meshes into the plastic and cannot creep under load.

Parts:

  • reused: one cut Z belt

Do:

  1. Work on the gantry off the printer, upside down, A/B motors up.
  2. Lay one belt end on a front idler's or drive's serrated pad, teeth down.
  3. Leave ~10 mm of belt past the pad.

check Check

Belt teeth are meshed into the pad's serrations, not sitting on top of them. The belt leaves the pad straight, not skewed.

Source: Voron manual p.111 · Voron manual p.106 · Video: Part 4 @0:10:12

Step 06.6 — Fit the lower belt clip

What you're looking at: The lower blue clip, one large hole and one small, goes on now, indented face down onto this first belt end. Its look-alike, the twin-hole upper clip, is already on top of each corner from Ch 05.

Parts:

  • [a]_z_belt_clip_lower_x4 ×1

Do: Drop the lower belt clip onto the belt, indented face down onto the belt. Line up the clip's small hole with the frame's M3 hole and its large hole with the M5 hole.

check Check

The clip lies flat with the belt captured under its indented face; both holes line up with the frame underneath, no offset.

Source: Voron manual p.111 · Video: Part 4 @0:12:33

Step 06.7 — Fit the Z bearing block

What you're looking at: The Z bearing block tops the sandwich. Two screws run through block, lower clip and the corner frame into the reserved rail-slot T-nuts, clamping the first belt end. The cutout faces the upright, away from the build volume.

Parts:

  • reused: one Z bearing block with its M5 nut
  • M3×30 SHCS ×1
  • M5×30 BHCS ×1

Do:

  1. Set the Z bearing block on the lower clip, cutout outward.
  2. Drive one M3×30 SHCS and one M5×30 BHCS through block and clip into the T-nuts, snug only.

check Check

Block, lower clip, corner frame, one M3 and one M5 through all, cutout outward, and the belt tail does not pull out.

Source: Voron manual p.111 · Voron manual p.112 · Video: Part 4 @0:12:53

Step 06.8 — Repeat at all four corners

What you're looking at: The same stack at the other three corners. The manual leaves the belts out of these drawings, but you now have four long tails hanging off the gantry. A trodden-on belt is a re-cut belt, and there is only ~400 mm spare.

Parts:

  • reused: the other three cut Z belts
  • reused: the other three Z bearing blocks
  • [a]_z_belt_clip_lower_x4 ×3
  • M3×30 SHCS ×3
  • M5×30 BHCS ×3

Do: Repeat steps 06.5–06.7 at the other three gantry corners. Coil each belt tail loosely and tape it to its own Y extrusion so nothing gets trodden on during the lift.

check Check

Four blocks fitted, all four cutouts pointing outward, four belt tails clamped and coiled. Nothing on this gantry needs a magnet.

Source: Voron manual p.113

pause Good stopping point · ~40 min since the last one

all four first belt ends clamped under their gantry corners with the Z bearing blocks on. Gantry still on the bench, belts hanging free — coil each tail and tape it so nothing gets stood on.

Step 06.9 — Fit the four lower Z joints to the Z carriages

What you're looking at: The z_joint_lower is the other half of each Z joint: it bolts sideways onto the MGN9 carriage riding the upright's Z rail, and its domed top is what the gantry's bearing block lands on. Four M3×20 per corner and no fewer.

Parts:

  • z_joint_lower_x4 ×4
  • M3×20 SHCS ×16

Do: Bolt one z_joint_lower to each MGN9 Z carriage with four M3×20 SHCS, driven horizontally into the carriage's tapped face. The domed top with the central bore faces up. Tighten evenly, corner to corner, firm.

check Check

All four joints sit flat on their carriages at the same rotation, and each carriage slides a few centimetres clear of the rail screws.

Caution

Rev D+ / LDO: This page (and p.116) is done before the gantry install on p.114, not after. LDO: "We recommend completing steps on page 115-116 then use the rubber rail stopper under the Z joints mid rail. This will allow you to set the Gantry on page 114 on the joints without the need for long zipties." src

Source: Voron manual p.115 · LDO Build Notes § Voron 2.4 build FAQ · Video: Part 4 @0:58:18

Step 06.10 — Park the four lower joints at a matched height

What you're looking at: A rubber rail stopper screws into a free rail hole and blocks the carriage. Screwed in directly under each lower joint it becomes a shelf, so all four joints park at the same height. The printed z_rail_stop_x4 does the same job at the rail top.

Parts:

  • Rubber rail stopper ×4 — from the Z rails
  • reused: the four z_rail_stop_x4 on the rail tops, if fitted

Do:

  1. Move each Z carriage to mid-rail; screw a rubber stopper into the free rail hole directly under it.
  2. Use the same hole from the same end at all four corners.
  3. Confirm a z_rail_stop_x4 caps each rail top.

check Check

Deck-to-joint-top height at all four corners is within ~1 mm, and each carriage stops on its rubber stopper when pushed down.

Helper: Reads the rule at all four corners and calls out any joint that sits higher.

Source: Voron manual p.115 · LDO Build Notes § Voron 2.4 build FAQ

pause Good stopping point · ~25 min since the last one

four lower Z joints on the Z carriages and parked at a matched height. Do not attempt the gantry lift until your second person is there: the next segment is one unbroken two-person move.

Step 06.11 — Turn the gantry over and stage the lift

What you're looking at: The gantry back the way it runs: A/B motors hanging down below the rear extrusion, Y rails on the underside, X rail facing the front, the four Z bearing blocks at the corners with their belt tails hanging. The frame is not front-to-back symmetric.

Parts:

  • reused: the gantry

Do:

  1. Turn the gantry the right way up: A/B motors down, Y rails underneath, X rail to the front.
  2. Mark Front and Back in tape on gantry and frame.
  3. Agree aloud who lifts which end.

check Check

Front and back marked and matching on both parts, belt tails taped clear, both people can reach their side without leaning over the bed.

Helper: Tapes the Front and Back marks, then holds one end while you turn the gantry over.

Source: Voron manual p.113 · Voron manual p.106 · Voron manual p.116 · Video: Part 4 @1:01:50

Step 06.12 — Two-person lift: tilt the gantry into the frame

What you're looking at: The lift itself. The gantry will not pass the four uprights flat, so it goes in tilted and levels out inside the frame. Hands on the Y extrusions only: the X carriage, the drive units and the belts are not handles.

Parts:

  • reused: the gantry
  • tool: a towel over the bed

Do:

  1. Cover the bed with a towel.
  2. Two people, one per Y extrusion, hands on extrusions only.
  3. Lift from above and tilt side-to-side: one Y extrusion enters the frame first, then bring the high side down.

check Check

The gantry is inside the frame, level, front to the front, each Z bearing block over its lower joint, and no belt pinched.

Helper: Lifts the other Y extrusion with you, hands on the extrusion only, and says stop if anything catches.

Source: Voron manual p.114

Step 06.13 — Set the gantry down onto the lower joints

What you're looking at: Each Z bearing block comes down onto the domed top of its lower joint. The last millimetre should be gravity, not force: if a block will not seat, slide that carriage along its rail rather than levering the gantry.

Parts:

  • reused: the gantry
  • consumable: long zip tie ×4, only without the rubber stoppers

Do:

  1. Lower until each Z block seats on its lower joint, nudging carriages until the bores line up.
  2. No rail stoppers? First zip-tie each corner up over the top frame rail.
  3. Let go one at a time.

check Check

The gantry rests on all four joints with nobody holding it. It does not rock, and no corner is visibly lower than the others.

Helper: Lowers the other side in step with you and lets go only when you say so.

Source: Voron manual p.114 · Video: Part 4 @1:10:15

Step 06.14 — Bolt the first Z joint together

What you're looking at: One M5×40 runs up through the lower joint's bore into the M5 nut, turning the two blocks into one Z joint. It stays light on purpose: the joint must swivel while the gantry is squared, and gets full torque once, hot, in Ch 14.

Parts:

  • M5×40 SHCS ×1

Do: From underneath, run one M5×40 SHCS up through the lower joint's bore into the M5 nut captive in the Z bearing block. Tighten lightly only: the joint must still articulate. Final torque is Ch 14 Step 14.6, hot.

check Check

The bolt threads in freely by hand for most of its length, and the joint still rocks slightly when you push the gantry corner.

Source: Voron manual p.115

Step 06.15 — Repeat at the other three joints

What you're looking at: The other three corners, same single bolt, same lightness. With four in, the gantry is properly attached to all four Z carriages and moves as one piece up and down the uprights.

Parts:

  • M5×40 SHCS ×3

Do: Add the other three joints the same way. Same light tightening on all four.

check Check

Four M5×40 in, all light. Lift gently under one Y extrusion: the gantry moves as one piece, all four carriages together.

Source: Voron manual p.116 · Video: Part 4 @1:20:06

pause Good stopping point · ~45 min since the last one

gantry lifted into the frame and bolted to all four Z joints, articulating freely. This segment could not be broken (two-person lift). Z belts are still unrouted; leave the idlers alone.

Step 06.16 — Extend all four Z idlers

What you're looking at: The Z idler is the toothed pulley on a sliding bracket at the top of each upright. Its bolt is the tensioner: it moves the pulley, changing how much belt the loop needs. The same four turns back parks all four identically.

Parts: none.

Do:

  1. The tensioner is the M3×16 under the blue slider, 2.5 mm key from below.
  2. Loosen it anticlockwise from below, out to the maximum before it comes undone.
  3. Tighten back 4 turns. Repeat on all four idlers.

check Check

All four idlers extended and backed off by the same 4 turns, counted out loud, with none of the four bolts fallen out.

Helper: Counts the turns aloud at each idler and ticks off each corner when it is done.

Source: Voron manual p.117

Step 06.17 — Loosen the four top belt clamps

What you're looking at: The blue upper clip on top of each front idler and A/B drive, fitted in Ch 05, is where the belt's second end clamps. Its two M5×16 also hold that frame to the Y extrusion.

Parts: none.

Do: At each corner, back off the two M5×16 BHCS on top of the front idler or drive until a belt slides under the upper clip. Do not remove them. Leave the M3×30 and M5×30 underneath alone.

check Check

A strip of belt slips under the upper clip at all four corners, and no first belt end has moved.

Source: Voron manual p.117

Step 06.18 — Route the first belt down and around the Z drive

What you're looking at: The belt tail runs down the rail side of the upright and wraps the toothed pulley in the Z drive, the pulley that lifts this corner. Teeth face inward so they engage; a belt running smooth-side-on over a toothed pulley skips teeth.

Parts:

  • reused: one Z belt, first end clamped

Do: Take the belt tail down past the lower Z joint on the rail side, around the Z drive pulley, and back up the run further from the rail. Teeth face inward, onto the pulley. Needle-nose pliers help.

check Check

The belt seats fully round the drive pulley, and teeth face each other between the two runs; teeth showing outside means a twist.

Source: Voron manual p.118 · Video: Part 4 @1:30:31

Step 06.19 — Take the belt up and over the Z idler

What you're looking at: The same belt continues up the run further from the rail, over the Z idler, and back down on the rail side toward the joint, closing the loop. The idler's flanges are all that keep the belt on it.

Parts:

  • reused: the same Z belt

Do: Run the belt up the far run to the top of the upright, over the Z idler pulley, and back down the rail side toward the Z joint. Teeth stay on the inside of the loop.

check Check

The belt sits centred in the idler's groove between its flanges, and both runs are vertical and clear of the extrusion.

Source: Voron manual p.119

Step 06.20 — Clamp the second end and pull it tight

What you're looking at: The returning end feeds in under the upper clip, teeth down on the frame's serrated top, as the first end did under the lower clip. Pulling the tail hard while you tighten takes out the slack; the tensioner only fine-tunes the rest.

Parts:

  • reused: the upper belt clip on this corner
  • reused: the two M5×16 BHCS on top of this corner

Do: Feed the returning belt end between the upper clip and the frame's serrated top, teeth down. Pull the tail hard and hold it while you tighten both M5×16, firm rather than crushed.

check Check

The long run plucks with real tension, not a floppy note; the tail does not slip and the first belt end is still clamped.

Helper: Pulls the belt tail tight and holds it while you tighten both M5×16 bolts.

Source: Voron manual p.120 · Video: Part 5 @0:47:55

Step 06.21 — Trim, fold and tie the excess

What you're looking at: The leftover belt past the clamp. Folded back and zip-tied it cannot flap into a pulley or a panel; left long rather than cut flush, it gives you one free re-clamp if the tension comes out wrong.

Parts:

  • consumable: zip tie, 3×150 mm ×1

Do: Fold the tail back on itself and zip-tie it to the running belt. Leave enough tail to re-clamp once if the tension comes out wrong, so do not cut it flush yet. Trim the zip-tie tail flush.

Check

The folded tail cannot flap into a pulley or panel, and nothing rubs as you move the gantry by hand.

Source: Voron manual p.120

Good stopping point · ~40 min since the last one

all four Z idlers extended, top clamps loosened, and the first Z belt routed, clamped at both ends, trimmed and tied. Never stop with a belt half-routed: finish the corner you are on.

Step 06.22 — Do the other three Z belts

What you're looking at: The other three corners, the same four operations each. Doing them in the same order every time is how you notice a corner that came out different, rather than discovering it as a QGL that will not converge.

Parts:

  • reused: the other three Z belts
  • consumable: zip tie, 3×150 mm ×3

Do: Repeat steps 06.18–06.21 at each of the remaining three corners. Do them in the same order every time, drive then idler then clamp, so you notice if one comes out different.

check Check

Four belts on, four tails tied. Every belt is fully seated on its drive pulley and its idler.

Source: Voron manual p.121

pause Good stopping point · ~30 min since the last one

all four Z belts routed, clamped, trimmed and tied. Belts are hand-even but not tensioned; do not touch the A/B front-idler tension screws (Ch 07's).

Step 06.23 — Even the four belts by hand

What you're looking at: The Z idler tensioner: the small bolt standing proud below the idler. Plucking a belt is a rough tension reading, and the four Z belts must be close to equal or QGL will not repeat. The measured 140 Hz target waits for Part B.

Parts: none.

Do:

  1. Pluck each Z belt on the short run between the top belt clip and the Z idler.
  2. Bring the four notes together with each corner's Z idler tensioner bolt: 2.5 mm key from below, clockwise for tighter.

check Check

All four belts sound within a semitone of each other, and lifting one gantry corner moves all four carriages together.

Helper: Plucks each Z belt in turn and says which note sounds lowest.

tip Tip

The CAD idler height is the 250 machine's. There is one of these at each of the four corners either way.

Source: Voron manual p.121 · Voron docs § Secondary printer tuning — A/B and Z belts · CAD: Voron 2.4r2 STEP @ de7e89d

Step 06.24 — Square the gantry to the A/B drives and lock the X axis

What you're looking at: Pushing the X extrusion back until both XY joints touch their drive units uses the two rear drive blocks as a square. The six bolts you tighten are the three per joint that clamp it to the X beam; no Z belt clamps here.

Parts: none.

Do:

  1. Push the X extrusion back until both X/Y joints hit the A and B drives together.
  2. Hold it there and tighten the three joint-to-beam bolts at each joint: two BHCS from above, one M5×30 from below.
If one side hits first

Then the A/B drive spacing needs adjusting; p.122 says you may need to. Loosen the bolts securing the B drive to the rear gantry extrusion, push the gantry back until both sides land together, then re-tighten. The bolts you tighten at each joint are the M5×10 (left) / M5×16 (right) BHCS from Step 05.38 and the M5×30 with its black washer from 05.39 — never the Z belt-clamp bolts at the drives and idlers, never the rail screws.

check Check

Looking down, the X extrusion is parallel to the rear frame extrusion pushed fully back, and to the front extrusion pushed fully forward.

tip Tip

This is a mechanical pre-square only. The manual's own QR code on this page (voron.link/cekh81l) points at the full procedure, which is Part B of this chapter.

Source: Voron manual p.122 · Voron docs § V2 Gantry Squaring · CAD: Voron 2.4r2 STEP @ de7e89d · Video: Part 6 @1:34:55

Step 06.25 — Release the gantry and check it moves freely

What you're looking at: With four belts on, the gantry holds its own weight; the zip ties and mid-rail stoppers were only scaffolding. Turning a Z drive by hand is the first end-to-end test of a corner. Never spin a connected stepper fast: back-EMF kills drivers.

Parts: none.

Do:

  1. Cut any long zip ties and unscrew the four mid-rail stoppers.
  2. Refit the rubber stoppers at the rail bottoms; printed stops stay on top.
  3. Turn each Z drive pulley by hand and watch that corner rise.

check Check

The gantry stays where the belts hold it unsupported, and turning any Z drive raises that corner smoothly with no slip or rubbing.

Helper: Watches the corner you turn and says whether it rises smoothly, with no slip.

Source: Voron manual p.122

pause Good stopping point · ~35 min since the last one

gantry squared against the A/B drives, X axis locked and released, everything moving freely by hand. Leave the machine powered off.

Step 06.26 — Close out the mechanical Z axis

What you're looking at: A closing page. The Z drag chain is the plastic link chain that carries cables from the fixed frame up to the moving gantry; its two black frame mounts and two blue retainer brackets are printed here and fitted in Ch 10.

Parts:

  • staged: z_chain_bottom_anchor ×1
  • staged: z_chain_guide ×1
  • staged: [a]_z_chain_retainer_bracket_x2 ×2
  • staged: drag chain 10×15 R28 ×1

Do: Bag the Z chain parts and label the bag Ch 10, manual p.200–204. Chain latches and mounting are Ch 10's.

check Check

One labelled bag holding the chain, the anchor, the guide and both retainer brackets.

Source: Voron manual p.123

pause Good stopping point · ~15 min since the last one

Z axis mechanically complete and logged. Stop here and go to Ch 07: Part B below cannot start until Ch 13 hands off to it at Step 13.34.

Checkpoint 06

  • Four z_joint_upper blocks fitted, each with its M5 nut seated, cutouts facing outward
  • Zero 6×3 magnets used; zero z_joint_upper_hall_effect parts printed or fitted
  • Four z_joint_lower on the Z carriages, four M3×20 SHCS each, all four bolted flat
  • Four M5×40 SHCS in, all still light — they are torqued hot in Ch 14, not now and not in Part B
  • Four Z belts routed drive → idler → clamp, teeth engaged on every pulley, none twisted
  • Both belt ends clamped at every corner: the first under the lower clip and bearing block, the second under the upper clip's two M5×16; tails folded and zip-tied
  • Four belts pluck to roughly the same note; nothing rubs anywhere in ±30 mm of Z travel
  • The six XY-joint-to-X-beam bolts (Steps 05.38–05.39) fully tightened with the gantry held back against both A/B drives (p.122); Z belt-clamp bolts and rail screws untouched
  • Gantry holds its own height on the belts; zip ties and mid-rail stoppers removed
  • Z-chain parts bagged and labelled for Ch 10

Next: Ch 07 — A/B belts and tensioning — Part B (Ch 06b) below cannot start until Ch 13 Step 13.34 hands off to it.

Revali passing a gate
You built a gantry hanging level on four belted Z corners. 8 gummy worms.

Common mistakes

  • Doing p.114 before p.115–116. Wrestling a 350 gantry on long zip ties while trying to line up four joints. Fit the lower joints and rest the gantry on rubber rail stoppers instead — LDO note p.114–116.
  • Fitting the hall-effect block or a 6×3 magnet because the manual shows it. This kit has none (LDO p.145). If you printed z_joint_upper_hall_effect.stl, you printed the wrong file.
  • The block's cutout facing inward. It is the one orientation error on p.112 that the manual calls out, and it is invisible once the belt is on. Fix: check all four before belting.
  • Putting the twin-hole upper clip on the Z bearing block. The Z-joint stack takes only the lower clip (p.111). The upper clip sits on top of the front idler or drive, under its M5×16 pair (Ch 05, p.91, p.95).
  • Removing the top belt clamp screws at p.117, or loosening the wrong pair. The two M5×16 on top also hold the front idler or drive to the Y extrusion: loosen them until a belt slides under the clip. The M3×30 / M5×30 underneath hold the first belt end; leave them alone.
  • Cutting Z belts to 1200 mm and finding it is exactly not enough after the wrap. Cut ~1400 mm — long enough to wrap, and it still leaves ~400 mm of the kit's 6 m spare. Cutting four at 1500 mm consumes the whole reel.
  • Torquing the M5×40 Z joint bolts now. They stay light through Part B and get their final tighten hot, in Ch 14 (Voron squaring step 16). Tight joints here will fight every squaring adjustment you make.
  • Leaving a Z carriage unrestrained near the top of its rail. It slides off, the balls go on the floor, and the carriage is scrap.

Part B — Chapter 06b: Gantry squaring

Caution

Do this from inside Chapter 13, not now. Start Part B only when Ch 13 Step 13.34 sends you here, once the machine homes and QGLs. It needs a running printer, cold and open.

The procedure needs SET_IDLE_TIMEOUT, G28, QUAD_GANTRY_LEVEL and SET_STEPPER_ENABLE. It ends at Step 06b.16 by sending you back to Ch 13 Step 13.35. Final belt tension (Ch 14 Steps 14.4–14.5, cold, door open) and then the heat soak, the hot QGL runs and the hot tighten of the Z joints (Step 14.6) are Ch 14's, after the panels go on in Ch 11 Part B.

Why it is split out: the procedure's first moves are to fully release A/B belt tension and drop the lower Z joints. Anything you tension before this gets undone (survey §5.2 W1, §4.4 #2). Ch 07's A/B tension and the one you set at step 06b.15 are both provisional; Ch 14 Step 14.4 sets the final value.

Part B is transcribed from: V2 Gantry Squaring, docs.vorondesign.com — 17 numbered steps. Steps 1–13 are transcribed below with the original number cited on each (plus one added Z-belt step); steps 14–17 (soak, hot QGL, hot Z-joint tighten, restart) are handed to Ch 14 at Step 06b.16. Ellis' identical section is the same text. The manual's own p.122 QR (voron.link/cekh81l) points here.

Extra tools for Part B: 150 mm machinist square, digital caliper, 150 mm rule, phone spectrum app, hex 2.5/3/4 mm.

tip Tip

Z Locks make step 06b.8 easier by holding the gantry while the joints are off. Not required. src

Source: Voron docs § V2 Gantry Squaring

Step 06b.1 — Raise the stepper idle timeout

(no image — see text)

What you're looking at: A console command; nothing to look at. Klipper de-energises idle steppers after 600 s by default, and with the Z motors released the gantry falls. This sets the timeout to effectively never for the session.

Parts: none.

Do: In the console: SET_IDLE_TIMEOUT TIMEOUT=99999. The Z motors must stay energised and holding the gantry for the whole session. Nothing else in Part B happens before this. Voron step 1.

check Check

Command accepted, no error. The Z motors are audibly holding.

Source: Voron docs § V2 Gantry Squaring, step 1

Step 06b.2 — Home and level

(no image — see text)

What you're looking at: G28 homes the machine. QUAD_GANTRY_LEVEL, or QGL, probes four points and drives the four Z motors independently until the gantry is parallel to the bed. QGL corrects height only: it cannot see racking, which is what the rest of this procedure fixes.

Parts: none.

Do: G28, then QUAD_GANTRY_LEVEL. Let it complete cleanly. From here the machine stays homed and the Z motors stay holding. Voron step 2.

check Check

QGL converges within its retry limit. A machine that cannot QGL cannot be squared by this procedure.

Source: Voron docs § V2 Gantry Squaring, step 2

Step 06b.3 — Set the Z belts to 140 Hz

(no image — see text)

What you're looking at: Plucking a measured 150 mm span and reading the lowest peak in a spectrum app turns belt tension into a number; 140 Hz is Voron's figure for the 9 mm Z belt. Four Z belts at four tensions make QGL wander.

Parts: none.

Do:

  1. Jog until a top belt clip sits 150 mm below its Z idler centre.
  2. Pluck that span; adjust the tensioner until the lowest peak reads ≈140 Hz.
  3. Re-check all four after a move, then QUAD_GANTRY_LEVEL.

Added step, not in the official squaring procedure: do it only after the idle timeout is raised and the machine is homed, so the Z motors hold the gantry throughout. Measure the span from the idler axle down to the clip. The tensioner head sits under the blue slider and takes a 2.5 mm key from below; clockwise as you look up at the head is tighter (verify on bench — the note rises). Voron's "fixed side" is this end of the belt, the one fixed at the joint (verify on bench). Uneven Z belts are a named cause of a high-σ, non-repeatable QGL, and squaring with mismatched Z belts wastes the session (survey §4.3). This is the working setting QGL squares from; Ch 14 Step 14.5 sets it for the last time, cold, before the closed-chamber soak. src

check Check

All four Z belts read 140 Hz ±5 Hz, and they still do after the gantry has moved and come back; QGL converges again afterwards.

Helper: Holds the phone at the belt span and reads the lowest peak aloud after each pluck.

Source: Voron docs § V2 Gantry Squaring, step 1 (prerequisite) · Voron docs § Secondary printer tuning — A/B and Z belts · Ellis' Print Tuning Guide § V2 gantry squaring

Step 06b.4 — Park the gantry in the middle

(no image — see text)

What you're looking at: Parking the gantry mid-volume is purely about access: the steps that follow need a hex key on the XY joint bolts from above and from below.

Parts: none.

Do: Jog the gantry to the centre of the build volume from Mainsail or the touchscreen. You need to reach both the top and the bottom of the gantry comfortably. Voron step 3.

check Check

You can get a hex key onto an XY-joint bolt from above and from below without contorting.

Source: Voron docs § V2 Gantry Squaring, step 3

Step 06b.5 — Disable only the A and B motors

(no image — see text)

What you're looking at: Disabling only the two CoreXY motors lets you push the X extrusion around by hand. The Z motors stay energised because they, and nothing else, are holding the gantry off the bed.

Parts: none.

Do: SET_STEPPER_ENABLE STEPPER=stepper_x ENABLE=0 then SET_STEPPER_ENABLE STEPPER=stepper_y ENABLE=0. Only these two. The Z motors stay enabled: they are holding the gantry. Voron step 4.

check Check

The X carriage now moves freely by hand; the gantry does not sink.

Source: Voron docs § V2 Gantry Squaring, step 4

Step 06b.6 — Release the A/B belt tension completely

What you're looking at: The two front idler tensioners, backed fully off. The A/B belts pull the X extrusion diagonally, so any tension left in them drags the gantry back out of alignment while you are trying to align it.

Parts: none.

Do: Back both front idler tensioners fully off until the belts are fully disengaged. If tension remains with the idlers fully backed off, release the belt ends from the X carriage. Voron step 5.

check Check

Both A/B belts are slack enough to lift off their runs by 10 mm with one finger.

Source: Voron docs § V2 Gantry Squaring, step 5 · image Gantry-ABTension.png

Step 06b.7 — Confirm access to the Z and XY joints (the side panels are not on yet)

What you're looking at: Voron's step 6 is written for a finished, panelled machine and takes the two side panels off purely for access. The render shows the side panels, and behind them the four Z joints in the corners and the two XY joints on the gantry.

Parts: none.

Do: Your side, back and top panels are not on yet, so there is nothing to remove. Confirm that all four Z joints and both XY joints are reachable with a hex key, top and bottom. Voron step 6.

check Check

Clear access to all four Z joints and both XY joints.

Source: Voron docs § V2 Gantry Squaring, step 6 · CAD: Voron 2.4r2 STEP @ de7e89d

Step 06b.8 — Unscrew and drop the lower Z joints

What you're looking at: The four lower Z joints, unbolted and slid down their rails, away from the gantry. With them out of the way the gantry hangs on its four Z belts and settles into its own natural position, the position you build the joints back to.

Parts:

  • reused: the four Z-joint M5×40 SHCS

Do: Take the M5×40 out of each Z joint and slide the four lower joints down their rails, away from the gantry. Do one at a time and keep a hand on the gantry. Voron step 7.

Warning (Voron): "Make sure your printer is on a (fairly) level surface. Unlevel surfaces could cause your gantry to swing too much to one side. It doesn't have to be perfectly level; just don't do it on a hill!"

check Check

All four lower joints are clear of the gantry, the gantry hangs on the four Z belts alone, and it is not swinging.

Helper: Steadies the gantry corner you are working on while you take out its M5×40.

Source: Voron docs § V2 Gantry Squaring, step 7 · images ZJoint-Lowered.png, ZJoints-Lowered.png

Step 06b.9 — Partially loosen the X/Y joints

What you're looking at: The three bolts that clamp each XY joint to the X beam: two BHCS from above and one M5×30 with its black washer from below. Loosened just enough, each joint slides along the X extrusion, and that is how the gantry's width is adjusted.

Parts: none.

Do: At each XY joint, loosen only the three bolts clamping it to the X beam: two BHCS from above, one M5×30 and washer from below. Both sides. Loose enough to slide by hand, no looser. Voron step 8.1.

check Check

Each X/Y joint slides along its extrusion under firm hand pressure, and nothing else was loosened.

Source: Voron docs § V2 Gantry Squaring, step 8.1 · images XYLoosen-Top.png, XYLoosen-Bottom.png · CAD: Voron 2.4r2 STEP @ de7e89d

Step 06b.10 — Partially loosen the A/B joints and the front idlers

What you're looking at: Two A/B drives, two front idlers. On each, the top M5×16 pair through the upper clip and the bottom M3×30 + M5×30 under the bearing block clamp a Z belt. Each drive also has two M5×10 above and two below, into the rear beam.

Parts: none.

Do: Ease every circled bolt just enough to slide by hand: each A/B drive, both clamp pairs and the four rear-beam M5×10; each front idler, both clamp pairs. Voron warns: "Don't overdo the belt clamps!" Voron steps 8.2 and 8.3.

check Check

All six printed assemblies can be nudged along their extrusions by hand. Every Z belt end is still gripped, top and bottom.

Caution

This corner hangs from its Z belt. The top M5×16 clamp its second end, the bottom M3×30 / M5×30 its first. One corner at a time, about a turn. Voron: "Where there are Z belt clamps, ensure that you do not loosen the bolts to the point of the Z-belts releasing. Only loosen enough to allow for adjustments."

Source: Voron docs § V2 Gantry Squaring, step 8.2–8.3 · images ABLoosen-Top.png, ABLoosen-Bottom.png, IdlersLoosen-Top.png, IdlersLoosen-Bottom.png

Step 06b.11 — Level the gantry onto the Z joints

What you're looking at: Slide the six loosened assemblies along their extrusions until the gantry's four corners land over the four lower Z joints. Voron's two conditions: the Z joints feel flush along the side, and the M5×40 slides in without hitting the sides.

Parts: none.

Do:

  1. Slide the six loosened assemblies until the gantry sits on the four lower Z joints.
  2. At each corner raise the lower joint and start the M5×40 by hand: it drops in without coaxing.

check Check

Both Voron conditions met at all four corners, no A/B joint rotated, and the four-point gap measurement inside tolerance.

Helper: Writes the four gap readings into the table as you call them out.

The four-point gap measurement (bench check, not in the official text)

With the caliper's depth rod, measure the horizontal gap between each Y extrusion and the frame upright beside it, at front-left, rear-left, front-right and rear-right. Front and rear on the same side must agree within 0.5 mm — a difference is the gantry skewed in the frame. Left and right must agree within 1 mm — a difference is the gantry off-centre. Then stand a machinist square on the front frame extrusion at each front corner, blade against the Y extrusion: no light under the blade at either corner. Write the numbers down; you repeat this at 06b.12 and 06b.14.

Point Measured (mm) Pass
Front-left (left Y ↔ front-left upright)
Rear-left (left Y ↔ rear-left upright)
Front-right (right Y ↔ front-right upright)
Rear-right (right Y ↔ rear-right upright)

Source: Voron docs § V2 Gantry Squaring, step 9.1–9.2 · images XAdjust.png, YAdjust.png, Alignment-Side.png, Alignment-Hole.png, Alignment-AB-Good.png, Alignment-AB-Bad.png

Step 06b.12 — Retighten everything except the X/Y joints

(no image — see text)

What you're looking at: Everything you loosened gets tightened again except the XY joints. Those stay free because the next step pushes the X extrusion hard against the two drive units and tightens the joints in that position.

Parts: none.

Do: Tighten every extrusion bolt you loosened at 06b.9–06b.10 except the three joint-to-beam bolts at each X/Y joint, left for de-racking. Z belt clamps included. Re-run the flush-and-bolt-slides check at all four corners. Voron step 10.

check Check

A/B joints and front idlers tight, top and bottom; the M5×40 still starts by hand at all four Z joints; the four-point measurement unchanged.

Source: Voron docs § V2 Gantry Squaring, step 10

Step 06b.13 — Reinstall the lower Z joints, lightly

What you're looking at: The four M5×40 go back in, light again. Light because the de-racking and the QGL runs that follow both need the joints free to articulate; they get their only full tighten hot, at Ch 14.

Parts:

  • reused: the four Z-joint M5×40 SHCS

Do: Slide the four lower joints back up and run one M5×40 into each. Lightly only: the joint must still articulate freely. Voron step 11.

check Check

All four in. Each joint still articulates when you push the gantry corner sideways.

Source: Voron docs § V2 Gantry Squaring, step 11 · CAD: Voron 2.4r2 STEP @ de7e89d

Step 06b.14 — De-rack the gantry, then tighten the X/Y joints

What you're looking at: Racking is the gantry sitting as a parallelogram instead of a rectangle: QGL passes happily on a racked gantry and the parts come out skewed. Pushing the X extrusion hard against both drive units squares it against the only reference the machine has.

Parts: none.

Do: A/B motors disabled, belts still slack: push the X extrusion fully back against both drives until both joints bottom out. Hold it there and tighten the three joint-to-beam bolts at each joint, cross pattern, a bit at a time.

Only those six bolts; the drives, idlers and Z belt clamps stay as 06b.12 left them. The Voron doc delegates the method to Nero3D's de-racking video rather than writing it out; this is that method in words.

Voron's own note on this step: "Make sure to come back here afterwards! The following steps are still important."

check Check

Pushed fully back, both X/Y joints contact their drives at the same instant; the square shows square at both front corners, forward and back.

If one side still leads

Loosen the X/Y joint bolts and repeat — the extrusion crept while they came up. If racking persists after two attempts, the community fallback is to loosen each A/B belt's anchor at the X carriage until the belt slides through under a firm pull, pull both belts to equal tension with pliers while feeling the tooth engagement, then re-anchor. Described in the Voron forum's de-racking thread. Re-measure the four points from 06b.11 afterwards and confirm the same-side pair still agrees within 0.5 mm.

Source: Voron docs § V2 Gantry Squaring, step 12 · Nero3D — de-racking video · Voron forum — de-racking thread · CAD: Voron 2.4r2 STEP @ de7e89d

Step 06b.15 — Re-tension the A/B belts to 110 Hz (provisional, cold)

(no image — see text)

What you're looking at: The A/B belts get their second tension here, still provisional, because 06b.6 released whatever Ch 07 set. 110 Hz measured over a 150 mm span is Voron's figure; a plucked frequency only means something with a stated span.

Parts: none.

Do: Move the X extrusion until the X/Y idler centres are 150 mm from the front idlers. Pluck that span and adjust each front tensioner to ≈110 Hz, going back and forth until both match. Move the extrusion and re-check.

Voron step 13. 110 Hz ≈ 2 lb, deliberately at the low end. Ignore voronldo.com's 80–100 Hz figure for a 350: it names no span, which is what makes a frequency meaningful (survey §4.3). This is a cold, open-machine working value; Ch 14 Step 14.4 sets it for the last time with the panels on, cold and door open, just before the soak, so do not chase the last few Hz here. src

check Check

A and B read within a few Hz of each other at ~110 Hz, and still do after the gantry has moved and returned.

Helper: Holds the phone at each belt span and reads the lowest peak aloud after each pluck.

Source: Voron docs § V2 Gantry Squaring, step 13 · Voron docs § Secondary printer tuning — A/B and Z belts · survey §4.3 / §7.5

Step 06b.16 — Hand off: RESTART, then back to Ch 13 Step 13.35 — panels (Ch 11 Part B) and Ch 14's final tension and hot lock-in come after

(no image — see text)

What you're looking at: Voron's steps 14–17, the heat soak, the hot QGL runs and the hot tighten, need a chamber that closes, and the panels are not on yet. So squaring stops here, cold: gantry square and de-racked, Z joints light, A/B belts at a working tension.

Parts: none.

Do:

  1. Run RESTART, so the idle timeout from 06b.1 returns to the config default.
  2. Go back to Ch 13 Step 13.35 and finish Ch 13.
  3. Leave the four M5×40 light: nothing set in this part is final.

Voron step 17, done now rather than in Ch 14 because the M5×40 stay light for days, not minutes. That step is G28, re-QGL, Z=0, bed mesh and the first cube. Then fit the back, side and top panels and the Clicky-Clack door (Ch 11 Part B). Final A/B and Z belt tension, cold and door open at 14.4–14.5, then the heat soak, the 3–5 hot QGL runs and the hot tighten of the four M5×40 Z-joint bolts at 14.6, are Ch 14 Part B.

check Check

RESTART completed, SET_IDLE_TIMEOUT back to the config default, the four M5×40 still light, and the gantry holding its height.

Source: Voron docs § V2 Gantry Squaring, steps 14–17 · Ch 14 Part B — Belts, final tension · Ch 11 Part B

Checkpoint 06b

  • SET_IDLE_TIMEOUT TIMEOUT=99999 set first (Step 06b.1), machine homed and QGL'd (06b.2) before any belt was plucked or any bolt touched
  • Four Z belts measured at 140 Hz over a 150 mm span (Step 06b.3), all four within ±5 Hz — set finally at Ch 14 Step 14.5 (cold, same session as 14.4)
  • Only stepper_x and stepper_y were disabled; Z motors held the gantry throughout
  • A/B belts were fully slack before any adjustment was made
  • At every XY joint only the three joint-to-beam bolts (Steps 05.38–05.39) were loosened; at the A/B drives and front idlers both Z belt-clamp pairs were eased only enough to slide, no Z belt end slipped, and all were retightened at 06b.12
  • Both A/B joints checked for rotation against the good/bad reference images
  • At all four Z joints, the M5×40 starts by hand with the joint raised — no coaxing
  • Four-point gantry-to-frame gap recorded: same-side front/rear within 0.5 mm, left/right within 1 mm
  • Machinist square shows no light at both front corners, gantry forward and gantry back
  • A/B belts re-tensioned to a provisional 110 Hz over a 150 mm span, matched to each other — final value is Ch 14 Step 14.4
  • Four Z joint M5×40 bolts still light — they are tightened hot in Ch 14, not here
  • RESTART run at Step 06b.16; idle timeout back to default; next page is Ch 13 Step 13.35

Next: Ch 13 Step 13.35 — re-heat and re-QGL after squaring; then Ch 11 Part B.

Revali passing a gate
You built a square, de-racked gantry on four light Z joints. 1 gummy worm.

Common mistakes (06b)

  • Doing this before Ch 13. Four of the seventeen steps are g-code. Attempting it dry means guessing at "level" with no QGL to check against.
  • Plucking the Z belts before the idle timeout is raised and the machine is homed. Klipper's default 600 s timeout releases the Z motors mid-step and the gantry sags onto whatever is under it. Steps 06b.1–06b.2 first, every time.
  • Tensioning the A/B belts in Ch 07 — or here — and treating that as final. Step 06b.6 undoes Ch 07's, and Ch 14 Step 14.4 sets the real one with the panels on, cold, immediately before the closed-chamber soak. Both earlier values are working values.
  • Overdoing the belt clamps at step 06b.10. The gantry is hanging on the Z belts, and at each A/B drive and front idler both bolt pairs clamp one: the top M5×16 its second end, the bottom M3×30 / M5×30 its first. Ease them just enough to slide; a released end drops that corner. At 06b.9 only the three joint-to-beam bolts move.
  • Tightening the Z joints cold, here. The point of the hot lock-in (Ch 14 Step 14.6) is freezing the gantry at full thermal expansion; cold-tightening throws that away and shows up as first-layer inconsistency. They stay light from 06b.13 until Ch 14, and light through the rest of Ch 13.
  • Skipping the de-racking step because QGL passed. QGL levels the gantry in Z; it says nothing about whether the X extrusion is square to the Y axes. A racked gantry passes QGL happily and prints skewed parts.
  • Believing voronldo.com's tension numbers. 80–100 Hz (A/B) and 110–130 Hz (Z) conflict with the official figures and name no span. Use 110 Hz and 140 Hz over 150 mm (survey §4.3).

Next

After Part A: Ch 07 — A/B belts and tensioning (manual p.124–145) once Checkpoint 06 is clear; tension provisionally, because Part B will release it. After Part B: back to Ch 13 Step 13.35 (re-heat, re-QGL, Z=0, mesh, first cube); then Ch 11 Part B (panels and door); then Ch 14 Steps 14.4–14.6 for final belt tension (cold), then the hot soak and the hot Z-joint tighten.

Source: Voron docs § V2 Gantry Squaring, steps 14–17

pause Good stopping point · ~60 min since the last one

gantry squared and de-racked cold, A/B belts at a provisional 110 Hz, four Z-joint M5×40 still light, RESTART run. Part B is one session by design: it starts by releasing all A/B tension, so stopping part-way leaves the machine unusable. Do not tighten the Z joints and do not chase the belt numbers — both are Ch 14's (belts cold at 14.4–14.5, joints hot at 14.6).