idea on ooze and retraction

Hi All,

After I interrupt a print, meaning I cancel it and do no retraction, material will ooze out of the nozzle (of course).

My question is, does the length of the oozed thread indicate how much retraction I need to avoid oozing?
In other words, will it be a good indicator to determine the retraction needed for that combination of extruder, hot end and material?

It makes sense, don't you think?

Procedure would be: Insert new filament material, heat up the hot end, extrude some material, wipe nozzle and wait. Measure length of ooze and calculate retraction.

Lykle

I don't think that would work. The longer you leave the nozzle sit, the longer the drool hanging from it. Settings to correct that would be quite different from the dynamic settings required for good print quality.

I would think a mechanical solution that slides a cover over the nozzle whenever a retract command occurs would work. That would give perfect "retraction" under both static and dynamic conditions.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]

I do dual nozzle PLA printing, and I never have a problem with oozing from the inactive nozzle. The key points are:

* Retract some filament immediately. I retract 10mm, because that was the slic3r default and I have never tried reducing it.

* On deselecting the tool, RepRapFirmware sets the nozzle temperature to standby temperature. For PLA I use 150C standby temperature. This is low enough to prevent oozing.

The same could be done on pausing a print, i.e. retract some filament and deselect the tool.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

For some hotends and materials 10mm retract spell disaster. I usualy use 1mm.
Fast retract and fast movement speed (less time to ooze) proved pretty good for me. For dual printing i use independent printheads where the nozzle is covered when in park position.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

Quote
Srek
For dual printing i use independent printheads where the nozzle is covered when in park position.

That's a great solution, although a bit high on the cost/complexity side. The reduced standby temperature is fine if the nozzle changes are infrequent (separated by Z), but is very hard on print times if there are nozzle changes on every layer,particularly for prints with relatively short layer times where the heat-up time becomes a larger fraction of the total.

Print times, ooze and lower moving mass were the main reasons why i went for dual X. It turned out not to be THAT cimplicated.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

Good point about the reduced moving mass, I hadn't thought of that. How did you do it, two carriages sharing the same linear guides, with a motor at each end?

Check my youtube channel and my website on this
[youtu.be]
The DuoCube shouldbe released later this year

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

That's looking really good. So that would need six stepper drivers? I'm curious which electronics you prefer for that?

Edited 1 time(s). Last edit at 04/24/2016 05:19PM by JamesK.

Currently i use a Rumba, next to be tested is a RADDS. Only Marlin cuurently supports dualx, i hpe the 32 bit version will work as well as the 16 bit

Edited 1 time(s). Last edit at 04/24/2016 05:37PM by Srek.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

It looks like they may have added dualx support to repetier firmware, so it might be worth checking that out if there are any problems with Marlin. Repetier also claim support for Due +RADDS (obviously I haven't tried any of these features out).

Repetier only supports the clone mode, but not full dual.

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[www.bonkers.de]
[merlin-hotend.de]
[www.hackerspace-ffm.de]

Ah, disappointing.

Dual X is coming to RepRapFirmware too, but probably not for a few more weeks.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

My point was not about oozing as such.
It was about using the initial oozing as a test to see how much retraction is needed while dialling in a new material/hot end combo.

It might be used as an indicator of the needed amount of retraction.

Quote

My question is, does the length of the oozed thread indicate how much retraction I need to avoid oozing?
In other words, will it be a good indicator to determine the retraction needed for that combination of extruder, hot end and material?

Easy fix of oozing before or after printing is to retract filament 4 to 5 mm.
The amount of retraction depends on nozzle diameter, layer height, filament type, and hot end.

I saw Lulzbot mini physically wipes out the ooze after printing session by moving the nozzle on a cleaning pad.

Edited 1 time(s). Last edit at 04/26/2016 05:56AM by janpenguin.

Quote
Lykle
My point was not about oozing as such.
It was about using the initial oozing as a test to see how much retraction is needed while dialling in a new material/hot end combo.

It might be used as an indicator of the needed amount of retraction.

I think whilst this might have some merit as a rule of thumb or a guide, the reality is that the amount of retraction required, is the amount which improves print quality and eliminates strings, ideally without slowing down the printing process too much, or retracting too far into an all-metal hotend using PLA running the risk of jamming it. It is essentially a process of trial and error. Whilst a wades extruder/J-head combo which might be seen as about as standard as it gets in 3d printing probably works well with slic3r's standard retraction settings, many other combinations of extruder/hot end will need individual tuning. This thread [forums.reprap.org] is a discussion of how to tune retraction on a flex3drive extruder but the general principles apply. As you can see the amount of ooze is a factor, some hot ends ooze more, high temps=more ooze but its not really that important.

Some sort of shutter over the nozzle would be a great way to prevent ooze, but it would have to be reliable, fast and not hit the object being printed.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions