Idea for doing multiple extrusion with one extruder

[LesterCHall]

Warning: this is just an idea, it is untested at this time. I just had to describe it to you so I don't explode in a giant vapor cloud from my enthusiasm for what is possibly a very exciting technique of 3D printing. It goes like this, beginning with a picture that really helps explain it.

bridging.jpg

OK, on the left we have a support and on the right we have the desired part. Notice that the desired part is not printable with a single extrusion printer. Enter our new technique: we print the support with a support filament, then we let it cool while changing to our desired part filament, then we print our desired part. If the step up is not too high and a bit further apart than shown perhaps, we have accomplished dual extrusion with a single extrusion printer! The details of just how much of this sort of thing we can get away with are related to the geometry of your printer's extruder near the nozzle. All low-hanging parts must be considered such as the parts fan on my ROBO3D printer which may need to be removed to make this work.

I don't know what to call this technique, perhaps time division extrusion or stepped extrusion for an example. One could see usefulness of it in making printed circuit boards or in printing parts with gently curved undersides that would otherwise require support material that needs to be cut off the part, damaging the finish. And if you do have a dual extruder, fear not - it just became a quad extruder with this technique (or a hex or and octal for that matter). Please note that the part must have at least one location where it touches the bed (shown in glass in the image) because you can't start a print in mid-air (well you can with some finagling, but let's keep it simple for now).

Well anyway, just thought I'd pass along this idea in case anyone found it useful. Enjoy!

Les