Zits occuring on every layer

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artemis
Posts: 7
Joined: Sun Jan 21, 2018 8:32 pm

Zits occuring on every layer

Post by artemis » Sat Jan 27, 2018 2:12 am

I have an interesting issue Im trying to figure out. Wondering if perhaps anyone here has run into something like this.

Printer: Formbot Raptor 400x400
Code: Marlin 1.1.8
Hotend: E3Dv6 Gold Edition (issue applies to 3 other e3dv6 clones as well)
Outline/Perimeter Shell: 2

No matter what I print I will get a zit on the corner where the layer begins. When it starts it appears fine but as soon as the second pass (outer perimeter) layer begins it will create a zit on that corner. This happens on every single corner and ALWAYS at the location where the layer begins. I have played with retraction settings, coast, wipe, and reduced jerk settings significantly yet this problem persists with 100% certainty that it will occur again on every layer starting corner. I have tried printing as slow as 20mm/s - all to no avail.

Any thoughts on what could possibly be occuring here? Anything in the Marlin code I should be considering beyond slicer settings?

Picture:
Image

Thanks!
-Art

chumm
Posts: 176
Joined: Thu Jun 15, 2017 11:24 am

Re: Zits occuring on every layer

Post by chumm » Sat Jan 27, 2018 4:12 am

This looks like a retraction issue, but possibly combined with a temperature issue. The filament appears to be oozing while traveling to start the new layer, which is what retraction is designed to prevent, but printing at a higher temperature can accelerate the ooziness of the filament.

Here's a really quick test print to help you try settings without having to wait too long between prints. I'd start by printing one with your current settings, then try dialing down the temperature to the low end of the filament's range and seeing what difference it makes, followed by revisiting retraction settings.

https://www.thingiverse.com/thing:2219103

artemis
Posts: 7
Joined: Sun Jan 21, 2018 8:32 pm

Re: Zits occuring on every layer

Post by artemis » Sun Jan 28, 2018 2:29 am

Thanks for that model, I printed it half a dozen times with different settings. I want to say my temp is/was pretty close.. for PETG I was printing at 235 and it did that entire print until the very top there was 1 small string across it. I printed again at 230 and on take 1 it had zero strings, second take it had 1 small string again at the very top.

I've continued to play with the retraction settings, currently sitting at .5 coast and 5.50 wipe and im still not really seeing a difference.. It's interesting because while I thought maybe I was pushing filament and that was causing the zit but instead the zit occurs immediately when the second perimeter pine begins like that first bit of filament it drops just a little too much creating that zit. Perhaps I need to play more with the extra restart distance. It's currently at 0. I had played with this before but it's been a while.

I thought that maybe changing the outline direction to "outside-in" might help - same issue.

artemis
Posts: 7
Joined: Sun Jan 21, 2018 8:32 pm

Re: Zits occuring on every layer

Post by artemis » Sun Jan 28, 2018 3:48 am

Quick picture just to show the variation.. This is with -.01 extra restart distance. If I set it to -.02 it still occurs I just have a gap immediately before the gap. Will include that picture.

with -0.01 extra restart distance:

Image


--------

with -0.02 extra restart distance:

Image

chumm
Posts: 176
Joined: Thu Jun 15, 2017 11:24 am

Re: Zits occuring on every layer

Post by chumm » Sun Jan 28, 2018 5:32 am

Yeah I see what you mean, in the latter print it's clear that the line is starting after the gap, so the extra filament deposit is occurring at the end of the line rather than the beginning of a new one.

I can't think of a physical reason this might be happening, nor of any Marlin setting that could cause this to occur, which leaves us with G-code as the possible culprit. What slicer are you using? Have you tried using an alternative slicer with default settings?

slippyr4
Posts: 224
Joined: Thu Jun 15, 2017 10:24 am

Re: Zits occuring on every layer

Post by slippyr4 » Sun Jan 28, 2018 9:55 am

Personally I’ve never found the need for extra restart, either positive or negative.

These issues are worse with PETG (I’m not sure is really possible to stop zits with PETG) and they are worse if you’re printing too hot (because the plastic is less viscous).

You don’t detail exactly what you’ve tried on your retraction settings, not what your values are. The raptor is, I think, direct drive into an e3d v6 hotend? You will probably be wanting about 1.8mm retraction, and perhaps 0.2-0.3mm coast. But what speed are you retracting at? Generally you want as fast as your extruder can cope with without skipping steps or grinding filament. Try 60mm/s.

What filament have you used in each of the photos?
Self-built Prusa i3 MK2 clone
My things: https://www.thingiverse.com/slippyr4/designs
My Prusa firmware port for ramps & MKS : https://github.com/slippyr4/Prusa-Firmware

artemis
Posts: 7
Joined: Sun Jan 21, 2018 8:32 pm

Re: Zits occuring on every layer

Post by artemis » Sun Jan 28, 2018 6:10 pm

This occurs regardless of filament, that first Grey image is PETG eSun solid grey, the Orange is Plasfil PLA, I have some others I've done in black PETG (inland), white PETG (priline), ocean blue PLA from tonerplastic. Essentially everything exhibits those same exact zits and you can watch it occur with 100% accuracy. Whatever corner the print begins at when it comes around to begin the second pass (or at the very end of the first pass) bam! there's a zit!

Slicer: Simplify3D (I have not tried another slicer yet).
Retraction settings are:
0.8mm ret distance
-0.10 extra restart distance
0.32 vertical lift
60mm/s ret speed
0.50mm coast
5.50mm wipe

Thats correct the Raptor is direct drive - I replaced the clone e3d hotend with one of those new E3Dv6 Bling models (Gold Edition) kits. I'll try to up the retraction as well and the coast.

slippyr4
Posts: 224
Joined: Thu Jun 15, 2017 10:24 am

Re: Zits occuring on every layer

Post by slippyr4 » Sun Jan 28, 2018 8:18 pm

As an experiment, might I suggest you try:

1.8mm retraction
0 extra restart
0 vertical lift
60mm/s retraction speed
0.2mm coast
2.0 mm wipe

And compare how that turns out.
Self-built Prusa i3 MK2 clone
My things: https://www.thingiverse.com/slippyr4/designs
My Prusa firmware port for ramps & MKS : https://github.com/slippyr4/Prusa-Firmware

artemis
Posts: 7
Joined: Sun Jan 21, 2018 8:32 pm

Re: Zits occuring on every layer

Post by artemis » Mon Jan 29, 2018 10:45 pm

Here's the print with those settings (same zits)

Image

chumm
Posts: 176
Joined: Thu Jun 15, 2017 11:24 am

Re: Zits occuring on every layer

Post by chumm » Tue Jan 30, 2018 9:59 am

I think it would be worth trying another slicer, not to replace your chosen slicer, but to isolate a clean batch of settings in your gcode.
Slic3r Prusa edition isn't too hard to get set up if you're pretty familiar with your printer. You can use one of the default print settings (I'd go with 0.15mm optimal) and default Prusa PLA settings. You'll just need to set up your printer in the printers tab, which is mostly just setting the bed dimensions and adding any custom G-code for bed leveling, etc. After that just drag the STL file onto the plater tab, arrange it how you like, then click export G-code on the right and you should be good to go. This will at least allow you to verify if the problem exists within gcode or not.

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