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This universal x-carriage allows your choice of Bear or Prusa carriage with your choice of extruder. Bear/BNB, Prusa, and Bondtech upgrade extruders are supported....

BNBSX Short Ears MK3S
Bunny and Bear Short Ears MK3
Bunny and Bear Geared
Bear
Prusa MK3 R3
Prusa MK3S R4
Bondtech I3 Upgrade

This BNB extruder x-carriage has belt paths for both Bear and Prusa x-axes. The upper one is for Bear x-axis, the lower one is for Prusa x-axis. Push belt ends into slot corresponding to your axis.

Because this is based on the BNB Easy Motor Service carriage for Bear extruder, you also gain simple motor bolt access for BNB and Bear extruders.

BNB Short Ears extruder should clear stock Prusa motor x-end when used with this carriage.

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Assembly Guide https://bunnyscience.dozuki.com/Guide/BNB+Universal+X-Carriage/3?lang=en

For Bear and BNB family extruders...
This carriage also moves extruder 1.5 mm closer to x-axis, but maintains same dimensions for most bolts inserted through x-carriage. Note that the middle air plenum bolt that connects extruder body to x-carriage must be 8 mm cap head.

For Prusa extruders...
Carriage is 1.5 mm thinner than Prusa x-carriages but bolt bore depths were compensated to maintain bolt lengths. However, please verify proper fitment. Most critical are the two MK3S R4 extruder bolts passing through the hot end air plenum. Please verify your bolt lengths before tightening. Also, cable dress should be done "Bear" style rather than following Prusa conventions.

Combined with the BNB Short Ear Extruders' already pushed back motor, this carriage moves the motor to a fraction of a mm in front of the Z-axis T-nut

Bunnies verified this carriage on both Bear and Prusa x-axes. It works as intended. Just be certain to use the correct insertion slot - Top for Bear, bottom for Prusa. Also, it is best to insert a short pit (two teeth long is sufficient) of belt into the empty slot BEFORE attaching belt ends.

Genuine Gates 2GT belts are thinner and much easier to insert than most Chinese GT2 belts.

As in the Skelestruder, you should stiffen the belt holding teeth of the carriage by stuffing the unused belt path with a two tooth long, piece of 2GT belt.

Please print all three parts of this carriage rather than attempting to mix with older x-covers.

* If used with short body MKS3 sensor extruders, Double check lead dress for hot end wires when x-carriage is max left and print bed max forward BEFORE XYZ calibration. Use current BNB Universal x-carriage which has better cable passage for hot end.

Change Log

BNB7S - upper cover now secured with 5 screws to symmetrically balance clamping forces on each bearing.

Mid-plenum screw is now M3 x 8 mm, but should be cap head instead of socket head, especially if used on Prusa axis.

Added spacer for use when extruder is BNBSX. Spacer allows standard M3 x 30 mm screw for upper left motor bay screw.

BNB8S - Tightened central portion of belt path by 0.2 mm.

BNB9S - Self aligning bearing pockets and improved nut pockets.
Changed to short bottom cover that permits belt access without removing lower cover.

BNB9Si - improved printability of overhanging bolt recesses with sacrificial membranes. Printing as a thin, but complete overhang results in cleaner geometry. Drill through membranes to open through holes.