A couple of us where discussing a solution to multi filament with a single

3D Printing
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A couple of us where discussing a solution to multi filament with a single nozzle a couple of weeks ago. This seems a very elegant solution

Originally shared by HACKADAY

Let’s talk multi-material printing on desktop 3D printers. There are a lot of problems when printing in more than one color. The easiest way to do this is simply to add another extruder and hotend to a printer, but this reduces the build volume, adds more…
http://hackaday.com/2016/09/28/prusa-releases-4-extruder-upgrade

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Something I think many of us had thought of long ago but nobody had ever implemented until now. Seems Josef is only a handful of people actually innovating any longer.

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@ThantiK ​ with the latest feature releases it really seems so

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I wonder when somebody will come up with a cleverr idea to get rid of the tower

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@Carsten_Wartmann with a darker filament selection for just fast multi color, not multi material prints, the infill could be the wipe. pretty limiting with translucent lighter colors though as it would show through the surface.

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@ThantiK dual-feed was done years ago. This is the first time I’ve seen quad-feed though.

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Old Italian project from 2014… work with simple ramps too marlinkimbra firmware is just enable for it.

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I like the gpio multiplexing, I’ve suggested that on a couple different projects and never seen it actually done.

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@Nick_Parker I did it back on my Prusa i2 way way way back. I installed stacking headers on my allegro drivers, stacked them, and pulled out the enable pins to enable each driver individually.

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@ThantiK I may be misunderstanding how the enable pin works, but as I understand it that’s slightly suboptimal (edit: Ignore this value judgement. I guess this is good for some applications, but bad for others) because you’re actually turning the motors off when not in use. So you lose microstep positions at the very least, and if there’s any outside force on the axis (eg, pressure on a filament feed) you might lose your actual position slightly.

Though actually reading the article again, I don’t like Prusa’s solution any better. Sounds like he’s switching the actual motor leads using SSRs to avoid buying extra drivers. That’s got all the same issues…

I’d like to see someone multiplex the STEP pin. ie use a couple gpios and some simple boolean logic chips to configurably connect STEP from one “axis” on your controller to an arbitrary number of stepper drivers’ STEP inputs. Share the DIR pin as well, so one step/dir output from the controller can run arbitrarily many axes, and the inactive axes will hold their positions.

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Printing will evolve to a zenith never attempted.