7. Z Axis

Z Top Pulleys & Rails

Attach the Z top pulley housings before linear guides. The pulley housings prevent linear blocks from falling out.

Z top pulley housing ⇔ frame

RH bolt m4 x 10 (2)
Flanged nut m4 (2)

For each linear guide, 3 bolts will be enough.

Front Z linear guide ⇔ frame

MGN12C 250mm linear guide (1)

Bolt m3 x 10 (4)
Nut m3 (4)
Washer m3 x 8 x 0.8 (4, optional)

Rear Z linear guide ⇔ frame

MGN12C 250mm linear guide (1)
Bolt m3 x 10 (3 ~ 5)
Nut m3 (3 ~ 5)

In some versions the holes on ACM back panel was not expanded, please clamp the rail and ACM panel using a washer and a nut:

Bolt m3 x 15 (3)
Washer m3 x 8 x 0.8 (3)
Nut m3 (3)

Actions

Refer to Hardware type & legends for the fonts and meanings in the labels.

[For Beta Kits only]

As shown in the photo, two holes were missed on the vertical Z frame. For the beta version, please use this temporary printed housing before a new metal housing is sent to you.

XY rear pulley set

Rear pulley housing ⇔ frame

RH bolt m4x10 (x4)
Flanged nut M4 (x4)

Actions

Put the XY rear pulley sets on here so you won't remove the rear ACM panel in the next chapter.

ACM Panel

Rear ACM panel ⇔ frame

Bolt m3 x 08 (4)
Bolt m3 x 10 (2)
Nut m3 (6)
Washer m3 x 8 x 0.8 (6)

Bottom ACM panel ⇔ frame

Bolt m3 x 08 (6)
Nut m3 (6)
Washer m3 x 8 x 0.8 (6)

Actions

[For Beta Kits only]

Please expand the 4 holes to 10mm so the bolt heads which are part of the main structure can touch the hard metal surface but not the softer ACM.

Belted-Z Drive

Printed Z stepper mount (STL here) ⇔ frame

Bolt m3 x 10 (4)
Nut m3 (4)

NEMA8 1:20 planetary gearbox Z stepper

2GT pulley 16T 6mm-bore, not 5mm-bore (1)

Actions

Here use hand-tools only. An electric tool breaks the nut slots easily.

For each nut slot in the stepper mount, clean the 3mm bolt hole with a drill bit and pinch all debris left inside to prevent blockage.

Gently press 4 M3 nuts into the slots in a Z stepper mount.

Make sure the nuts are pressed deeply enough by testing the nut thread with a m3 x 10 bolt.

If unfortunately the slot is expanded and the nut can rotate in the slot, insert a small flathead screw driver to block the nut from rotating.

Usually 3 nuts will be enough to secure the Z stepper, in case that one nut slot is broken accidentally.

Bed Brackets & Z Belts

Assemble in the order below:

Bed bracket ⇔ Z linear block

Bolt m3 x 06 (4)

Z belt ⇔ L-shape belt clamp base

70cm per Z drive (3)

Belt clamp ⇔ L-shape belt clamp base

Bolt m3 x 10 (4)
Nut m3 (4)

L-shape belt clamp base ⇔ bed bracket

Bolt m3 x 10 (2)
Nut m3 (2)

Printed bed fixed mount (STL here) ⇔ Left front bed bracket

Bolt m3 x 10 (1)
Nut m3 (1)
Washer m3 x 8 x 0.8 (1)

Printed bed expansion mount (STL here) ⇔ Right front bed bracket

Bolt m3 x 10 (1)
Nut m3 (1)
Washer m3 x 8 x 0.8 (1)

Background knowledge

To deal with thermal expansion and to prevent the bed from wobbling, a Kelvin kinematic coupler is used in the bed:

The left-front point is fixed in the front bracket
The right-front point floats in a slot, allowing the bed to thermally expand in X direction but restrict rotation.
The rear point floats on the surface of rear bracket, allowing the bed to thermally expand freely.

Actions

Refer to Hardware type & legends for the fonts and meanings in the labels.

Z Belt tension

As long as the belt teeth won't slip when you manually drag the bed bracket under the friction of the gearbox stepper, the tension is high enough. Too high tension might reduce belt life and print quality.

Exams

Make sure the top pulley and bottom pulleys are aligned with the belt clamp. The belt should not make clicking sound in operation.
Make sure both edges of the belt have the same tension by adjusting the positions of top pulleys.

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