This is a remix of the Kossel Magnetic Ball Stud Carriage (https://www.thingiverse.com/thing:932959) by Tim Watson (aka wittmason), which is in turn a remix of the Kossel Mini Spring String Effector and Carriage (https://www.youmagine.com/designs/kossel-mini-spring-string-effector-and-carriage) by Forerunnert. It makes the following changes:
Ball stud distance -- Tim Watson's version placed the magnetic ball studs 48.4mm apart. I provide several variant .stl files for this design, with distances of 48mm, 51mm (to match my Ugly Parametric Magnetic Effector, https://www.thingiverse.com/thing:2819851), and 55mm (to match Duet3D's Delta Smart Effector). You can make a simple change in OpenSCAD if you need something else, as described shortly....
Mounting hole location -- I provide two sets of mounting hole locations: The same 20x20 location as Tim Watson's original, which should work with most sliders; and a 20x16 arrangement, customized to work with the DB Delta Printer 2020 Slider (https://www.thingiverse.com/thing:984766) by DanBuro. If you want or need another location or Y spacing, see below....
Stud nuts -- I've added slots to hold nuts with which to secure the ball studs, vs. relying on the plastic to hold them securely, which in my experience is unreliable.
- More parametric -- I've moved some hard-coded inline values into variables that can be more easily located and adjusted in the self_locaking_carriage-v3.scad source file. These variables include both the ball stud distance (rodSeparation, line 18) and the mounting hole Y (Z when oriented for use) locations (bottomScrewY and topScrewY, on lines 19 and 23, respectively). After making changes, you must re-render the design (F6 in OpenSCAD), then export a fresh .stl file with your changes.
In total, I provide six .stl files: 20x20 and 20x16 mounting variants of the 48mm, 51mm, and 55mm designs. I've used the 51mm and 55mm variants myself, but never the 48mm version, which I'm providing because it seems to be a common rod spacing choice for effectors. (I have printed that version and checked to see that the ball studs can be properly secured. The blue version in my photos is this test print.)
Forerunnert's original design was intended to support a spring-based redundant/emergency magnetic arm spring, via the hole in the top center of the carriage. I'm not using this feature, but I've left it in place because I may want to experiment with a flying extruder in the future, and that could be a useful mounting location for it. It does no harm if it's not used.
To use this design, you will also need, per carriage:
2x magnetic balls with stud mounts -- These are available from Ultibots, Filastruder, and others.
4x M3 screws -- Three of these should be 7mm plus whatever length is required to grip the slider; the remaining one must be 14mm plus that extra length.
- 2x or 6x M3 nuts -- 2x for the ball studs and 4x for the screws (assuming the slider design needs them).
I recommend using PLA; PETG proved to be too flexible. I haven't tried with ABS.