7. Bed

Degrease the bed

Aluminum bed
IPA degreaser, soap water, etc.

Action

Remove any possible machining oil, stains stayed on the surface of aluminum bed before pasting the heater pad and magnetic rubber pad.

Attach AC-powered Silicone Rubber Heater

Aluminum bed
AC-powered silicone rubber heater
Magnetic rubber of PEI plate (optional)

Exam

No bubble is allowed!

Action

Note that a Cube bed with different hole locations is shown below.

Repeat step 1 to 3 as shown in the picture and attach the silicone rubber heater to the bottom side of aluminum bed. If you have ordered a PEI sheet, attach the magnetic rubber to the top side of aluminum bed after the whole bed assembly is completed so it covers the center leveling screw.

Make sure no air bubble between heater and bed. If air bubble exists, heat will accumulate at that point due to no metal to conduct heat. Glue on the heater will vaporize and bubble will continue growing until you notice the awful smell. Then you’ll have to peel the whole heater off, clean the glue and re-install it.

Bed legs

Bolt m3 x 15 (3)
Bolt m3 x 10 (2)
Nut m3 (7)
8mm steel ball with hole (3)

Actions

Connect Thermal Fuse

Ceramic thermal fuse 150°C
Ceramic terminal block
High temperature RTV (room-temperature-vulcanizing) silicone

Thank Cube owner Brad Stinson for sharing the ceramic terminal block method.

Exam

Measure the resistance with a multimeter at the 2 connectors to AC power source. The resistance should be:

About 35 ohm for a 110V heater
About 138 ohm for a 220V heater.

Action

Stripe the sheath so 5~8mm wire is exposed for the ceramic terminal block.

Connect the wires to the block first before pasting them to the heater pad.

There is another repeatable 150°C thermal switch buried under the rubber patch.

Optionally apply high temperature RTV to to prevent the edges from separation over time. (Image courtesy: SK-Tank owner Michael K Johnson)

Kinematic Coupler

Printed bed fixed mount (1, STL here)
Printed bed expansion mount (1, STL here)

Bolt m3 x 8 (4)
Washer M3 x 8 x 0.8 (4)
Nut m3 (4)

Cable tie or string

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

Exam

After ABL sensor fine tuning, secure the bed with a cable tie or a string to prevent from falling in case that bed brackets are not at the same height or faulty Z movement.

Actions

Attach the two printed mount on the left bed brackets, and leave the right bed bracket empty. The right leg is floating on the bracket.

The bed mounts can be shifted left and right to meet your nozzle position.

Go3 bed coordinates

Use the coordinates of legs as the lead screw positions requested in the firmware.

Don't use the actual positions of lead screws because a leg and its lead screw move synchronously at the same height.

If you've pasted the PEI build plate at the center of the bed, use the coordinates in the first picture.

(-6.75, 40.0)

(-6.75, 270.0)

(316.75, 155.0)

If you're trying other build surface, take the coordinates in the 2nd picture for a reference.

Using a Go2 9-point bed

Bolt m3 x 15 (3)
Nut m3 (3)
8mm steel ball with hole (3)

Actions

Attach the bolts and steel balls at the pointed positions. For the right leg, attach the bolt close to the middle right point of the bed in the slot

Go2 9-point bed coordinates

Use the coordinates of legs as the lead screw positions requested in the firmware.

Don't use the actual positions of lead screws because a leg and its lead screw move synchronously at the same height.

If you've pasted the PEI build plate at the center of the bed, use the coordinates in the first picture.

(-15.0, 64.0)

(-15.0, 246.0)

(325.0, 169.5)

If you're trying other build surface, take the coordinates in the 2nd picture for a reference.

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