Originally shared by Frank Herrmann
Hello Friends, the first video about Idea and Design of XHTC is published. Please enjoy first episode and leave me a comment if you like this video. Maybe I can do something better or you want to know more about certain facts. Subscribe my channel if you need updates about this project.
Great project, thanks for sharing it.
Using four balls overconstrains the kinematic coupling. I expect there will be repeatability problems with the position of the tools.
Is the electrical connection through the balls for confirming the mechanical connection? I don’t understand the electrical disconnect for power and signals. Extruders will still need hear control when parked.
I like the magnetic release idea. Unlike a plastic wedge, that should never wear out.
I look forward to seeing the project develop. Very interesting.
@Dale_Dunn Very interesting remark about the kinematic coupling, I have taken a closer look at it on the following website:
Would you agree with me if three magnetic balls were enough?
“There are three linear degrees of freedom, the “x”, “y”, and “z” axis, and three rotational degrees of freedom around each axis commonly called pitch, roll and yaw.[2] If a system is under constrained then the two parts are free to move in one of the degrees of freedom.”
Parking an extruder seems to be easy at first, of course I have to think about how to configure the Marlin firmware correctly. Hints and help is welcome!
Yes, three balls max for kinematic coupling.
The implementation I’m most familiar with is two balls and a flat, the first ball mated to a cone to control 3 DOF, the second ball mated to a slot to control 2 DOF, and the flat mated to another flat to control the last DOF. That was optimized for an aluminum casting.
For printed parts, I think the easiest and most precise to implement would be the Maxwell kinematic coupling: three balls, each mated to a slot formed by a pair of rods, embedded in printed parts. I could be wrong. The washers you used could be filed to simulate the cone and slot. Hmm. washers aren’t usually very hard, though. They may wear over time.
I’ve thought about a project like this for a few years. For me, the mechanical design is the easy part. The electronics and software modifications are beyond me. I think I heard somewhere that Marlin supports dual x-carriage printers. That seems like the place to begin. Hopefully it was implemented to be generalized to more than one extruder axis (E, F, G,…?).