I am ready to introduce a project of mine. I call it the T-bot.. It utilizes CoreXY kinematics and is spectra line driven. The frame is 30 mm extrusion that can be bought at a lot of different sources. Uses printed wheels only and no linear bearings or rods! My main design goal was to avoid linear bearings as well as openbeam, v-slot, or makerslide. While those are nice, a complete wheel/bearing package is around $4 a piece. This overcomes that with inexpensive, widely available 608 bearings and inexpensive printed wheels. I'm using M8 socket cap screws to hold up the corexy pulleys. This makes them strong and free of flexing.
Right now the x and y axes are functional and pretty smooth. Here's a video of them running: youtu.be/1-CuOnObo3k. I originally modded the carriages for belts, but ran out of belts. That's why I switched to spectra. I will update the carriages for spectra line. I also need to shorten them up a little bit so I can maximize build volume. I'm going to be using Wild Bill's extruder for now, until I upgrade it to use a Makerbot type extruder.
Credit goes to LoialOtter for the initial design of the carriages: thingiverse.com/thing:20659. Also I have to give credit to AndyCart for his spectra pulleys and inspiration on the eventual Z axis I will build with a UHMW nut from his design: thingiverse.com/thing:313048
Current frame volume is 350mm x 350 mm x 350 mm. Build volume is about 175 mm x 250 mm x 330 mm.