Topic: New extruder concept
Next year, I have it in my goals to build my own printer from scratch. As part of that, I had been looking at bowden Vs. Direct drive and the advantages and disadvantages of each. Then a thought occurred to me. Why not combine them?
So, what I am envisioning is a flex shaft system where the filament is fed down the center. The twisting of this tube feeds the filament by "screwing" just like the Z axis on our printers. The filament is free to move in one direction and the flex shaft rotates.
The result is that the filament is driven at the point of extrusion like a direct drive, but the stepper can be located elsewhere to reduce weight. Also, the space an extruder like this could save would allow for several extruders in a small space and low weight.
And additional thought to go along with this is a driven hub on the spool. The flex shaft could be a tap off this to keep the whole feed system synchronized and smooth.
Right now, it is just a concept and seems simple enough. I wanted to put the ideas out here for discussion before I start experimenting with it.