Rostock-compliant bushing carriages, marble joints

thingiverse

I was inspired by Etienne Labuschagne's idea published on http://www.thingiverse.com/thing:776611 and decided to print a couple of clamps in ABS to test the joint. I noticed that his design had some issues: 1. The joint is weak when forces are applied in the pull-apart direction, but it works well when pushing the clamps together; 2. The clamps take up too much space, which would result in a significant loss of build volume in the X/Y plane on my delta machine base. I decided to design my own solution to avoid these issues. I created a carriage with bronze bushings (8mm diameter x 12mm outer diameter x 15mm length) for a 60mm distance between linear rods. The carriage features an adjustable GT2 belt tensioner and gives a 24mm offset in printer radius, which is more than the original Rostock's carriage. The platform with clamps has a 33mm offset in the X/Y plane, matching the Rostock's platform. It retains the same mounting holes and thickness, allowing me to use the hot-end holder and z-probe designed for Rostock's platform. The mechanics are showcased in action on https://www.youtube.com/watch?v=lkXnUtAfmqY. The setup is still under testing and investigation. So far, it has worked for approximately 22 hours in printing mode without any issues. I updated the instructions on July 13, 2015, and on March 3, 2016, I noted that the joints are still functioning well, but other machine problems led me to redesign some parts.