I discovered "diamond" nozzles (name of the design, not the use of diamond material), which have multiple filament inputs (designs for 3 or 5) and a single output nozzle, see figure.

Diamond nozzle, 3-in 1-out

They look like a very good and compact solution to avoid or significantly reduce purge towers, where filament is wasted until the channel is primed, and to avoid a second hot end, which takes space and which could be oozing when unused, but I could find them only made of brass.

Are there hardened diamond nozzles, or equivalent systems which are lightweight and can avoid a second hot end, to print composite or abrasive materials?

  • $\begingroup$ Please help me understand how this eliminates purging. $\endgroup$ – cmm Jan 23 '20 at 14:07
  • $\begingroup$ It is just reduced to a very minimum amount, so that it could also be done in infill $\endgroup$ – FarO Jan 23 '20 at 15:27
  • $\begingroup$ Do we have any examples of this? I imagine that filament n would be withdrawn a bit to make room for filament n+1 in the hot-end/nozzle. How is this different from what the Prusa MMU2 does in terms of the required purging? Maybe I am out of context, but I don't see the basis of the improvement. I like it, especially if Bowden extruders work for you, but in what way is it a special solution to the purging problem? $\endgroup$ – cmm Jan 27 '20 at 13:48
  • $\begingroup$ Prusa in prusa3d.com/downloads/manual/prusa3d_manual_mmu2_eng_1_01.pdf discloses 60-100 mm^3 purge. This hotend reprap.org/wiki/Diamond_Hotend primed with 50 mm^3 (20 mm filament), but here they said that the actual "mixed color region" is much smaller, like 0.2-0.25 mm: reprap.org/forum/read.php?2,731431,735286#msg-735286 They also say that "The only part where all 3 filaments come together is 0.4mm diameter and 2mm long" which is very small... $\endgroup$ – FarO Jan 27 '20 at 15:10

Yes, but there is no hardened version of the "Diamond" nozzle design. Basically when you want to use a hardened nozzle, or a Ruby nozzle in combination with color mixing (I specifically refer to mixing solutions as the melting chamber is smaller than filament changing solutions and your request for none or minimal purging towers) you need to order a design that accommodates the replacement of the nozzle. In such a case you can remove the standard nozzle to replace it for a hardened version.

There are a few 2 and 3 filament input designs that are offered on typical auction and Chinese selling sites. Below is an example for the Zonestar M3 mixing color hotend with a replaceable nozzle.

Zonestar M3 mixing color hotend side view Zonestar M3 mixing color hotend front view

  • 1
    $\begingroup$ Indeed the keyword for finding what I wanted is "mixing hotend" $\endgroup$ – FarO Jan 22 '20 at 8:46

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