Cube3 Back-2-Basics Bowden Tube (B2B Project)

Description

This is the last of 3 parts belonging to the Back-2-Basics Universal Cartridge Upgrade for the 3D Systems Cube 3rd Generation 3D Printers. This is the bowden solution between the modified cartridge bulkhead and the Cube3 B2B extruder housing. This part is recommend to be made from PLA on the Cube3 left side extruder. Rotate the parts 180 degrees if using the right extruder. This unique implementation of the bowden tube for the Cube3 printers eliminates the need for push-fittings. Push-fittings tend to fail for Cube3 users because keeping the tube from rotating is a problem when handling Cube3 hubs and extruders. This implementation solves the rasping of the grippers on the tubing forcing tube shortening and breaking fittings. Never buy another bowden tube due to gripper damage and never replace fittings again. Your investment is limited to a single 1/2-meter length of 4mm tubing to achieve the full B2B adaptation. This solution requires 'machining' a groove in the bowden tube. Basically, you are adding a 2mm wide, 1/2mm deep groove 5mm from the end of the tube. This groove will hold a 'circlip' to maintain the dedicated tube-nuts. A printable device to achieve this groove has also been developed and will be posted later. You can find 2 versions of the device at Print3DForum.com under Cube3/Universal hub. I will continue to improve the tools before release. Currently, I am using a 1.8mm wide section of the thick tube buried in the stock cartridge case and slitting it. This is 'the keeper' of the tube. You probably need to clean up the seam-pip where the circlip resides on the hotend tube-nut. The case bulkhead side also needs to seat fully. I am working on a cube3-specific print to make the circlip. This will be added when completed. Basically, any tough ring the size of the mating bulkhead and extruder housing tube-nut counterbore would work if you don't have spare 'stiffening tubes; from salvaged cartridges. The stiffening tube is the larger tube placed over the smaller tube where the filament leaves the mechanism to the cartridge bulkhead. *Edit: I've added a printed version of the Circlip. It is a 70 micron print of the included STL file. If you set up your own print, make sure the seam is in the middle of the clip as this is one of three 'strong points'. Do be sure to adjust out any "elephant foot". I use a very generous gap to make these. Blue tape is a good way to make sure you get good adhesion. And as much as the Capricorn tubing is cool and all, I prefer to see my filament being fed into the bowden tube. And I will suggest testing your bowden tube ID. I have found a lot of 4mm PTFE tubes with ID of much less that 2mm. I qualify tubing by pushing a 2mm bicycle spoke through the tube. There should be minimal restriction along the 18" length. I highly recommend qualifying your tubing using this benchmark. Basically, flattened filament going through the driver mechanism can easily reach a width that a tube too small will trap the filament causing the print to fail. This is essentially the issue with 1/2 of the stock Cube3 cartridges. Stay tuned for further postings of the B2B Cube3 cartridge upgrade.

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