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Dual extrusion setup - Which to choose?

Posted by Banana_Luke 
Dual extrusion setup - Which to choose?
November 09, 2017 02:01PM
Hi Guys!

I was using the search function and also was googling it... but couldnt find any satisfying answer...

I am looking forward to build a dual extrusion system, because i want to print PVA and PLA... YEAH! Nice support material winking smiley I am really looking forward to make something like that...

My plans were about using the prometheus system, or more exact, just the splitter and run it via my own bowden extrusion system...

BUUUTTTT.... I am not sure about PVA and PLA beeing used with the prometheus system... What do you think? What alternatives do i have? which ones are the better ones to use with a Prusa clone?
I am really thankfull for any suggestion, since there is no real information out there ;/

cheers, luke
Re: Dual extrusion setup - Which to choose?
November 11, 2017 02:38AM
I'm not sure I like splitter systems for multi material. It relies on the temperature profiles being the same, or finding some sort of compromise between the material profiles. Large retractions needed also introduce a source of error and it generally has to be done on a bowden system. Capricorn bowden tubes have helped the issues surrounding bowden systems, but I hear that the large retractions needed for splitter systems doesn't get on well with the tight inner diameter of capricorn. Next up is splitter systems require purging, and PVA is expensive. I'm not sure I'd want most of my expensive PVA in a purge tower.

Separate hot ends are the answer in my opinion for true multi material systems. This adds a bit of bulk to the hotend gantry though depending on what system you get. E3D chimaera is nice and compact but again requires bowden (but will not have the same issues as splitter thankfully). You could go for independent X axis's, but this adds complexity. You could also get a lifting nozzle system. the ultimaker 3 uses this to lift the inactive nozzle out of the way. This is in my opinion the best style.
Re: Dual extrusion setup - Which to choose?
November 11, 2017 03:39AM
Hey!
Thank you for your reply.
As now I group the extruders as followed:
  • Extruders With a single nozzle (Prometheus System or Diamond Hot End, though they are different approaches)
  • Extruder With two sepperate nozzles and heater blocks (Basic dual extrusion)
  • Extruders with two in one block nozzles (no X,Y,Z problems --> Chimera or Ultimaker sys

For me I also tend to a two nozzle System now, though I was convinced that the Prometheus System, printing with one nozzle, is Ideal... But its not... Im afraid of the retraction (stringing inside the extruder) and the different temperatures of the materials needed for a nice extrusion...

So now im looking for the Chimera System...
As for Single nozzle extrusion: What do you guys think about the Diamond hot end?
Looking at the prusa Multi material system again... it looks so nice... but the waste of material... hummm.... Any further thoughts on this?

regards luke
Re: Dual extrusion setup - Which to choose?
November 11, 2017 10:13AM
Probably the best option for dual-material is IDEX (independent dual X carriages), but this requires much greater modifications to the printer.

Ian (deckingman) is an expert on Diamond hot ends, both 3- and 5-input versions. His blog is at [somei3deas.wordpress.com]. Click on tag "Diamond hot end".

Edited 1 time(s). Last edit at 11/11/2017 10:14AM by dc42.

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Large delta printer, and other 3D printer blog postings: [miscsolutions.wordpress.com]

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Re: Dual extrusion setup - Which to choose?
November 11, 2017 10:31AM
Hey ho!
Thanks for the blog article... Seems like he put a lot of effort in that.

The IDEX system seems realy interesting. I orderd to day some parts to start with a simple bowden system... Than I will upgrade to double bowden with dual extrusion and the Chimera hot end...

When this is working, I am happy and will give further updates and photos.

I also think that my reprap with wood frame is not "worth" upgrading... I think for an IDEX system a better "base" should be available. More stable, less noisy, enclosure and so on...
Re: Dual extrusion setup - Which to choose?
November 15, 2017 04:38PM
I think the way forward for multi-extrusion is via a tool changer.

I am working on a design for independent tool heads. Each one would have it's own "umbilical cord" for wiring, reverse bowden, flex/nimble style remote extruder drive, and possibly water cooling lines and Berd-Air cooling (as chamber will likely be heated).
Corexy gantry "cart" would simply pick whichever head is selected.
Clamping via kinematic coupling and magnet(s).
XYZ offsets handled in software, so they don't have to be physically identical.
Ideal nozzle geometry and temps for each material.
1) PLA
2) PVA
3) CF Nylon
4) Flexible TPU

Anyways, that's my plan.
Re: Dual extrusion setup - Which to choose?
November 17, 2017 02:06AM
Quote
StephenM
I think the way forward for multi-extrusion is via a tool changer.

I am working on a design for independent tool heads. Each one would have it's own "umbilical cord" for wiring, reverse bowden, flex/nimble style remote extruder drive, and possibly water cooling lines and Berd-Air cooling (as chamber will likely be heated).
Corexy gantry "cart" would simply pick whichever head is selected.
Clamping via kinematic coupling and magnet(s).
XYZ offsets handled in software, so they don't have to be physically identical.
Ideal nozzle geometry and temps for each material.
1) PLA
2) PVA
3) CF Nylon
4) Flexible TPU

Anyways, that's my plan.

Although it makes sense, the question is: Will there be enough demand for it considering the price ? To make such a system will be costly. Two different materials is nice (a rigid and a flexible one for ex.) but more than that ?
Different colors is a no for me as it can be done by mixing the dye in the hot end.


"You failed to maintain your weapon, son" (Harry Brown )
Re: Dual extrusion setup - Which to choose?
November 17, 2017 04:12AM
Regarding Systems with two nozzles, there is something else: You can have different nozzle diameters.
So it should be possible to print on Extruder 2 with PVA support, at a higher speed with a bigger nozzle and use a fine one for the rest of the print.

The question for the demand on the market is some kinda difficult, because there was no demand for 3D printers before they came up with the idea.

Nevertheless I understand the argument that it is not worth it, because looking at a modern CNC machine with interchangable tools, they need to be change to get connected with the engine. So having 2 or more engines in one CNC is not economic. Instead having 3 extruders parked on a 3D printer is still cheaper than a fancy interchangable system.
Re: Dual extrusion setup - Which to choose?
November 17, 2017 10:16PM
I tried a lot of solutions, and want to give my own opinion.
First:
Dual extrusion is not an easy thing.
Pva printing is totally different from Pla printing (so don't even think about a single nozzle system for this application, i had the original diamond, only usable with materials really compatible)
The only way to go, is 2 separate nozzle's, either 2 carriages or single carriage with a switching height solution like Ultimaker 3. 2 nozzles at same height on same carriage gives you a lot of problems.
Just some tips regarding PVA:
-Cura software has the best temperature management, it cools the not used PVA head down while not being used, and heats it up quickly so it is ready for the next layer just in time. If you do't use this feature, you will have clogged heads very soon!!
-PVA does not bond with PLA, so printing PVA on top of PLA is a bad idea, always let the PVA touch the buildplate, (horizontal expansion can help), or with other PVA.
-Expect printing time to go up almost 3X.
-Pva is extremely hygroscopic!! 24 hours left on the printer can ruin your filament because of moisture absortion. Keep it dry in a drybag with silicagel, even while printing!!!!, or use a Polybox (just google it, easy thing which you can build yourself)

My main filament use regarding supports:
Polymax PLA (better then ABS)
in combination wit Ultimaker PVA, or Polymax Polysupport (much easier to use, can be removed traditionaly)

Have fun, once it works, it is a nice evolution for 3D printing.

Edited 1 time(s). Last edit at 11/17/2017 10:22PM by RudydG.
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