X-Carriage for Bondtech Prusa Extruder MK3(+MK3S Add-on) (Revised X-Axis)

X-Carriage compatible with the MK3(S) Bondtech Prusa Extruder with the Revised X-axis

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Compatible ONLY with the Revised X-axis or Bear X-ends

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IMPORTANT: This carriage is compatible with stock frame only if you use "X-Carriage Back_Top 1.02S (MK) (Stock Frame)".
Assembly note for stock frame: Make sure to have the correct orientation when installing the X Carriage Back Top (StockFrame), the cutouts should be facing upwards.

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While converting my printer setup to use the Bondtech Prusa Extruder I felt like the Bear X-carriage provided some well needed utility that previous ones didn't. However, I saw few things that can be further improved, hence this remix.

The belt path cutouts can be a sore point of the X-Carriage, because different materials, print settings and print artifacts can heavily influence the designed tolerances. Leading to cases where its very hard to insert the belt, damaging the belt in the process and possible poor alignment, or it was loose, tending to skip teeth under tension with the existing geometry of the cutout.
While I'd prefer a belt clamp of sorts, my interim solution to remedy this was to edit the belt path to closely match the published specs of the 2GT belt. This gives a lot more surface area that the belt is in contact with the carriage, while not necessarily attempting to compress the whole belt too tight. Only the last few millimeters compress the belt and need a tool to be pushed all the way in. This results in the belt being easier to insert (up to those last few mm), and those last few mm ensuring the belt can keep its positioning while under tension.

The rest of the changes to the carriage came along while analyzing the CAD files and printed parts, that at least in my opinion, needed slight optimization.

Changes include:

• Adjusted belt "holder" cutout to closely match the genuine 2GT belt shape (compatible with GT2 but not GT3). This allows for the belt to hold a lot more tension without slipping, while still being easy to insert in the carriage.
• Belt is accessible even when the whole carriage is assembled
• All X-Carriage-back screws are now the same length and are fixed on the X-Carriage in the same way. It helps with ease of assembly as well with some cases where the layers were failing (delaminating) above the square nuts.
• X-carriage-back clamps the bearings more uniformly
• The cable holder was edited to have far less aggressive bridging
• The screw for the cable holder protrudes deeper into the X-Carriage, giving it more layers to resist the cable holder appendix breaking off. This change eliminated one zip tie holder, edited the remaining ones to be split (2 for the top cables, 2 for the bottom)
• Added "ribs" to the cable holder, to help out with better constraining the nylon filament guide (tested it with stock ~3mm nylon filament , and ~2.8mm)
• Further optimized for 0.2mm layer height printing, added bit more clearance for the belt and cables, reinforced some thin features.

In case you are swapping parts around (MK2.5-MK3), the only parts that are different and version specific are: X-Carriage and X-Carriage-Back Bottom. The files affected have appropriate name tags.

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**If you prefer to have the cutout for the "old" optical sensor (MK3) closed on the X-carriage, I've added a version ONLY compatible with the MK3S add-on **

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X-Carriage-Back has two versions, although I recommend using this one, it allows access to all screws that secure the extruder, making assembly a bit more convenient.

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STEP files are included for your modding pleasure and convenience. STL files were sliced and checked with Slic3r PE. Any constructive feedback is welcomed.

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