Pressure Advance + Slic3r PE retractions et al ... Funky results
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The branch like features are caused by an initial small blob of filament at the edge of the print. Then the next time the print head passes over this initial blob, if there is a blob of filament on the end of the nozzle, it gets "wiped off" and deposited on top of the first one. So the branch continues to grow with each pas of the nozzle. In my experience, a bit more retraction usually fixes it.
As someone else pointed out, there s PET-G and there is PET-G. Some brands are more prone to stringy behaviour than others.
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I should have mentioned that I use E3D SpoolWorks EDGE PETG mostly. It's a little on the pricey side, but the results have always been terrific.
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When my PETG quality made a major leap it was when I realized that my first layer being to close to the bed was causing the blobs I was seeing in my 50th layer. Once I gave it a little more room I notices my nozzle was not rolling boogers in the wide open spaces at higher altitudes.
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@jackatom74 said in Pressure Advance + Slic3r PE retractions et al ... Funky results:
When my PETG quality made a major leap it was when I realized that my first layer being to close to the bed was causing the blobs I was seeing in my 50th layer. Once I gave it a little more room I notices my nozzle was not rolling boogers in the wide open spaces at higher altitudes.
Good info ... i feel like my 1st layers are high off the bed if anything atm ... i seem to have to run a wide [ 8 loops ] skirt to get Z dialed in w/ babystepping - and I too found petg on buildtak especially - likes to start out a bit higher than i'd ever run PLA.
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I'd like to add an oddity happened last night on test print ... I altered the Slic3r PE profile settings to the numbers discussed above [ except for de-retraction was run at 15 mms vs. 10mms ] - but I had forgotten to mod the Press Adv in config.g prior to running the print start. But ... NP - sent a nifty command via the gcode console in DWS to change the Press Adv to .08 .... All cool ... except ...
The oddity was - my Y axis motor on non printing rapids, and faster printing moves - started whining - well making a noise Ive never heard before - ever. I tried increasing the speeds to see if that went away - nope. I tried slowing things down too - and that did change it and it went away. However; when you use the DWC interface for speed modifications, I suspect that also alters - ALL stepper moves, so I put speed back to 100% and left it till the top of the tips
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Im using Matterhackers [ they are just down the street from me ] 1.75 Aqua PetG Pro
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@deckingman said in Pressure Advance + Slic3r PE retractions et al ... Funky results:
The branch like features are caused by an initial small blob of filament at the edge of the print. Then the next time the print head passes over this initial blob, if there is a blob of filament on the end of the nozzle, it gets "wiped off" and deposited on top of the first one. So the branch continues to grow with each pas of the nozzle. In my experience, a bit more retraction usually fixes it.
As someone else pointed out, there s PET-G and there is PET-G. Some brands are more prone to stringy behaviour than others.
Thanks for that ... Matterhackers PetG Pro - Aqua 1.75
Do you feel as if that blob branch issue would be best solved by MORE retraction or higher Press Adv ?
Going by what fellow Duet user DHackney of sublime layers advises 1.0mm retraction [ should be plenty ]. Obviously not a hard fast rule but ... too hot perhaps / temps ?
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Another question I had about these print tests ... Should I have the expectation to get this 100% blob free - strings arent - to me the end of the world - surely Id prefer to never see one, but - is it reasonable expectation with a Duet wifi / E3d v6 - good bed and accurate frame/machine to hit this VERY near perfect ?
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It would help to know a bit more about your extruder and printer, but I don't see why string free prints couldn't be attainable, unless of course it's just the nature of the filament.
Try increasing the retraction by 0.05 mm during a print every few mm of height until the strings stop or you get an uncomfortablly long retraction, which for a Titan V6 all metal combo could be up to 2mm.
You can live adjust the temperature during the print as well. 5c at a time through the range of whatever the manufacturer recommends. Some like it hot, others not.
For pressure advance I look to see how much of a blob the end of a solid infill line looks like and increase it slowly until the end of the line seems to match the width of the line.
It would also help to do a test with pressure advance to see if it's actually helping or hindering.
I dunno if it's perfect but it's pretty decent. Any strings are tiny wisps.
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@phaedrux said in Pressure Advance + Slic3r PE retractions et al ... Funky results:
It would help to know a bit more about your extruder and printer, but I don't see why string free prints couldn't be attainable, unless of course it's just the nature of the filament.
Try increasing the retraction by 0.05 mm during a print every few mm of height until the strings stop or you get an uncomfortablly long retraction, which for a Titan V6 all metal combo could be up to 2mm.
You can live adjust the temperature during the print as well. 5c at a time through the range of whatever the manufacturer recommends. Some like it hot, others not.
For pressure advance I look to see how much of a blob the end of a solid infill line looks like and increase it slowly until the end of the line seems to match the width of the line.
It would also help to do a test with pressure advance to see if it's actually helping or hindering.
I dunno if it's perfect but it's pretty decent. Any strings are tiny wisps.
Thats a sexy benchy sir ... still yet to print one of those - only because everybody does. Maybe its time ...
Im not using firmware retraction - im slicing all those settings into the gcode, except Press Adv. Can I still send gcodes from the DWC for retraction settings that will override the sliced values ? Im not sure I understand how that works ...
On your solid infill line end test ... so Im clear [ and many thanks for all your help here btw ] - youre talking about like a single layer or more of 100% infil like rectilinear - where it melts over the interior perimeter line ?
P.S. - you remember your print speeds for that benchy ?
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To use firmware retraction with Slic3r PE it's as easy as checking the box in printer settings.
It's a little trickier in Cura. There is a plugin that will let you toggle it. https://community.ultimaker.com/topic/22743-printer-settings-plugin/Once you have it enabled you can then use the G-code console to modify the values on the fly. Once you find the values you like you can put them in config.g as defaults or add them to the start code areas in Slic3r for a specific filament.
I think that Benchy was 100mm/s, 0.2 layers. 400 accel, 60 jerk.
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Before I get excoriated on this - I set these - knowing mostly nothing about what they should be... Duet was my first ever used printer/board. I suspect Im a good bit OFF on these settings too.
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; Drives
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M569 P0 S0 ; Drive 0 goes reverse [ X Axis ] [ S0 = Rev / S1 = FWD ]
M569 P1 S0 ; Drive 1 goes reverse [ Y Axis ]
M569 P2 S0 ; Drive 2 goes reverse [ Z Axis ]
M569 P3 S1 ; Drive 3 goes forward [ E0 ]
M350 X16 Y16 Z16 E16 I1 ; Configure microstepping with interpolation
M92 X100.30 Y100.250 Z1600 E140.64 ; Set steps per mm
M566 X900 Y900 Z25 E250 ; [ Jerk Settings ] Set maximum instantaneous speed changes (mm/min)
M201 X500 Y500 Z280 E250 ; Set accelerations (mm/s^2)
M572 D0 S0.080 ; Set Pressure Advance [ need to check Jerk and Accel Settings to properly coincide here ]
M203 X6000 Y6000 Z280 E1200 ; Set maximum speeds (mm/min)
M906 X1600 Y1600 Z1600 E1600 I30 ; Set motor currents (mA) and motor idle "power saving" decrease factor as percentage [ I30=30% ]
M84 S10 ; Set idle timeout
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Those look like pretty good starting points to me.
Do you notice stringing printing other things? Those towers are designed to be a worst case scenario afterall.
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The other thing about using firmware retraction is that you can change it on the fly during the print.
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Im going to have to do some more testing and tweeking ... ran some non "benchy" type parts and I noticed the Press Adv is not dialed in ... Im not getting a solid line of plastic all the way to the END on solid infill. The line STARTS look pretty good , but there are defo lines od infill that have small gaps at the end.
So far now Im going to
- increase retraction from 1.00 to 1.25
- reduce Pressure Advance from .08 back to .065 / .060
- increase line width - back to .55 for my .50 nozzle
Additionally I need to get a handle on why my Y axis motor is now developed a whine at speeds above 30 mms
Hope to get this material dialed in - and then sort out how to change the slice method and move to FW retracton etc ... sounds mo bettah
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Consider tuning retraction and speeds first without any pressure advance, and then adding some in slowly after that.
I would say it really only starts to make a big difference when you start pushing speeds up around 100.
There was some pressure advance specific test files as well that make it easier to dial in separately.
