Here's what I've been thinking about multi-extrusion:

gplus
discussion
(Sahil Jain) #1

Here’s what I’ve been thinking about multi-extrusion:
I think the easiest and most failsafe method would be to have multiple nozzles arranged in the same heatblock.
That way, one does not need multiple heating outputs from his main board and there is a significantly reduced purge tower. There also wouldn’t be any chance of jamming in the filament path.

In terms of multiple materials, I think if coupled with a good heater, this should manage to do filaments ~15C apart.

What do you guys think?

(Moon Stone) #2

altho idk what that will be used in , i guess its a heat sink?
Still , sounds good

(ThantiK) #3

The problem with multiple nozzles in the same heatblock is that it’s almost impossible to get them to be exactly the same level without some tricks. They have a tendency to run into things, rip up previous layers, etc.

The reason people try to do single-nozzle is because it doesn’t have these issues.

(Ulrich Baer) #4

another issue is that you cook your unused filament. Also oozing will happen from the unused noozle.

(Sahil Jain) #5

@Ulrich_Baer I think that that is a common problem to all multi-nozzle setups and there are solutions to those. @ThantiK I think I can circumvent that if I mount it on something that can be rotated, therefore allowing for easy leveling.

(Ulrich Baer) #6

@Sahil_Jain what solutions? They normaly go into a standby temp. which prevent that and minimize oozing - also the are seperated so they don’t ooze onto your print.

(Tomáš Vít) #7

One nozzle will destroy the work of the other I am afraid. In dual nozzle systems there is a need to cool down (prevent oozing) and move the inactive nozzle away from active layer (lifting etc.). Only the best printers which mastered it both can print in combination with PVA and other tricky materials reliable and repeatedly with the same quality.

(Jon Gritton) #8

The problem of ooze, if not all the other issues already mentioned, is why you don’t see two nozzles and a single heat block. When the “unused” nozzle is at the same temp as the live one, all the material from the point of entry to the hot area is going to ooze out all over the place. E3D’s Chimera is the closest to this approach, but even that has separate hot ends.

(Este ban S) #9

Done it some years ago. Didend work out, ooze wqs okayish … i retrackted the unused filament 10mm and ther wher only a few drops
The problem is cooking. On a small part it works but after printting a singlecolor part ore one that oses mostly the one color, the unused nozzle always clogged. (This was testet on pla and worst woodfill) the remainigs are realy hard to get out.

(Ryan Carlyle) #10

Two-nozzle systems aren’t ideal but they do work fine if you’re careful about leveling and ooze control. There are lots of techniques to do this well.

  1. Shimmable mounts to provide fine adjustment of relative nozzle height
  2. Ooze shields placed closer to the print than the nozzle spacing, so the oozing nozzle repeatedly wipes across the ooze shield as the perimeters are printed
  3. Ram-purging the idle nozzle to get most of the molten plastic out
  4. Idle nozzle cooldown (requires separate hot blocks)

My question is, what usage case makes two nozzles in one hot block superior to separate hot blocks? Leveling difficulty is about the same, and the magnitude of XY nozzle offsets don’t really matter. Two hot blocks lets you print different materials temps, which is really important for soluble support (the main reason to do dualstrusion in the first place in my opinion).

(Griffin Paquette) #11

@ThantiK is right. Even if they are in the same block that doesn’t mean that they will be at the same level. The block itself could be off by a bit or the nozzles could be slightly more or less close to the block. Lots of factors.

The other issue is the fact that you just dropped the option of running two temperatures for two different materials. This is something that even a single head y splitter could do in theory if it had a low thermal mass and therefore a lower time to change temps.

(Sahil Jain) #12

Hmm, I agree with all of your points. Thanks for letting me know!

(Jeff DeMaagd) #13

I like your idea of wrapping around some fins onto the sides of the cooling block. If you’re careful you can apply that to the Chimera design. The dual block on the Chimera makes height adjustments easy.

(Brandon Satterfield) #14

If your machining was precise enough you could have your thread starts be exact on the nozzles ( indexing required ) and get the nozzle thread starts perfect, you could have a completely square nozzle, heater block assembly.

How are you going to get threaded heat breaks into the heat sink if they are threaded? Works in CAD, not in real life.

Not threaded into the heat sink? Like E3D has already done.

Now you are at 3 perfect machined planes and perfect thread starts on two non indexed parts (the heat breaks).

After these trials you are still dual extruding at one temp. No support/main filament. No Flexible/solid.

I can see your application having uses but there are road blocks along the way in manufacturing and materials.

(marc kerger) #15