Adapter plates for the extruder and hot end that allow you to use a Bowden cable on the Printrbot Simple beta.
Please note that as with many of the things designed for the original Printrbot Simple beta, this conversion is not usable with the current production Printrbot Simple, equipped with the direct drive extruder. For that printer, see dby's design at http://www.thingiverse.com/thing:217094
NOTE: This part, like many things designed for the Printrbot Simple Beta, is now outdated by the design changes made for the production version. The new printer uses a direct-drive extruder that has different attachments to the printer and the hotend, so these adapters will not work.
You'll need to print one plate for each end. Both have thin layers between the upper and lower holes that will need to be cleaned out; I recommend a knife or file for the hot end plate and a #40, 3/32" or 2.5 mm drill for the extruder plate. You may also want to clean out and smooth the cone on the bottom of the extruder plate, since it will help the filament feed more easily.
The plates are made for press-fit couplings that take 4 mm OD tubing and have a metric M5 thread. I bought my parts from Grainger because they would ship to the local store; other sources may have lower minimum quantities:
PARKER Tubing, 2mm ID, PTFE, Natural
NORGREN Male Adapter External Hex, Push In M02250405
You can tap the holes or thread the fittings in directly, though in that case it would be easier to form the threads with an M5 screw first. If you use a through tap be careful not to bottom it on the extruder plate.
To install, remove the extruder body from the Y-axis carriage and detach the Ubis hot end, then reinstall it in the hot end plate. You may need to trim the edge of the mounting hole with a knife or file to make up for the first layer being a bit wider; try not to remove too much plastic, because you want a snug fit. The 6-32 mounting screws should grab the hot end firmly and hold it square. Install the plate on the Y-axis carriage.
Install the extruder plate on the extruder body, making sure to line up the hole in the plate and the fitting with the hobbed bolt. Cut an appropriate length of tubing with a sharp knife to avoid deforming it, then chamfer the inside edge of the extruder end to make it easier to insert the filament. Make sure you don't end up with any chips of PTFE inside the tube, they'll clog your nozzle. The tubing will push into both fittings.
With less weight on the Y axis, you will probably need to re-level your build platform - but that's a good problem to have. . .