Printing with dual extruder

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sgeolog
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Printing with dual extruder

Postby sgeolog » Wed Jul 12, 2017 8:26 pm

Hello Guys,

I am printing 2 colors print and have problems. During printing with left nozzle, right one keep extruding. I don't know how to stop it. Changed a little bit retraction material amount, speed and min travel retraction but it did not help much.
1 picture is during printing,
2 - After and
3 is Nozzles after print is done.

You see circle on both sides of that print.
Can somebody help me with this please?

Thank you
Sergey
Attachments
During Print.jpg
After Print.jpg
Nozzles.jpg

Jetguy
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Joined: Tue Mar 22, 2016 1:40 am

Re: Printing with dual extruder

Postby Jetguy » Wed Jul 12, 2017 8:33 pm

Please read this thread in depth. There are limitations and tradeoffs of dual extrusion. One of the chief ones is that the non-printing nozzle will drip or ooze. There is no magical fix as a again, this is simply a limitation. At best you can use the techniques listed in that thread.

viewtopic.php?f=8&t=1902

Jetguy
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Joined: Tue Mar 22, 2016 1:40 am

Re: Printing with dual extruder

Postby Jetguy » Wed Jul 12, 2017 8:45 pm

Again, just understand the very basics of what we have.
With dual nozzles spaced 25mm apart in X axis, anything over 25mm wide is going to have the second nozzle drag over top the surface.
If both nozzles are not the exact same height, the lower nozzle will drag trough the layers of the other nozzle. Nozzle leveling is a skill.
Even with as much retraction as possible it's never going to remove all traces of plastic from the hot zone of the extruder. As such the extruder will drip from gravity. The ONLY things you can do is choose printing materials not prone to dripping AKA ooze, set extrusion temperatures as low as possible to still get good extrusion as this slows and limits ooze.
Last, use wipe walls as part of dual extrusion features, but still this ONLY mitigates some risk. On a big flat part as shown, you are simply fighting the impossible. The second nozzle is ALWAYS over the print on something that big, it's not catching the wipe wall often enough, there are limitations here.

This is again an area where the Mosaic palette and it's single nozzle filament splicing tech can provide superior results at the cost of using more filament and obviously the cost of the device. If you intend to do a lot of this type of advanced dual material printing, it is worth looking into and understanding the tech.

Jetguy
Posts: 1793
Joined: Tue Mar 22, 2016 1:40 am

Re: Printing with dual extruder

Postby Jetguy » Thu Jul 13, 2017 1:09 pm

Just to show failures happen even to me when trying to dual extrude, here is the classic ball and cube that the ball broke free from a nozzle strike and print bird nested after the extruders skipped in XY position (again, known root cause was the ball broke free, rotated, causing a bind and skipped step in XY).
Attachments
IMG_0786[1].JPG

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sgeolog
Posts: 98
Joined: Wed Apr 20, 2016 2:40 pm
Location: New York
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Re: Printing with dual extruder

Postby sgeolog » Thu Jul 13, 2017 4:14 pm

Jetguy,
Thank you for your time and explanation. I did printed before a lot of 2 colors objects and mostly did not have problems.
Maybe not perfect prints but good enough. Now I changed extruder to Bondtech. Printed few tests to calibrate x,y and printed 2 color octopus with wipewall. Looks acceptable. After that I moved hot ends again for some reasons and could not print good calibration detail. I thought z was wrong but... Printing now a detail in 2 colors which is flat... cannot get good result.


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