Author Topic: Print layer failure?  (Read 975 times)

Offline ddmckee54

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Print layer failure?
« on: September 11, 2018, 08:39:20 PM »
Since I've started using this spool of blue PLA I've noticed random times when it looks like the printer is screwing up, see the attached photo.  I know it's a crappy picture, but I had to take what I could get while the printer was working on the other part being printed.  This has occurred on several different parts,. and on different layers in those parts, so for now I'm going to assume that it is not something that Slicer is telling it to do.

If you look just to the left of the holes in the part being printed you'll see a series of ripples - for lack of a better term.  I was printing 2 identical parts at the same time and this rippling only occurred in one part.  I've only seen this since I started printing with this particular spool of filament.

Any 3D printing guru's that can tell me what could be going on?  I've been printing for a couple of years and still consider myself a Noob at this.

Don

Offline b.lindsey

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Re: Print layer failure?
« Reply #1 on: September 11, 2018, 09:17:24 PM »
Does it happen in the same place for more than one layer? Or if it does it again, is it always in the same place? My suspicion is the material but if it does it in the same place for multiple layers, that would suggest something in the slicer.
Bill

Offline ddmckee54

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Re: Print layer failure?
« Reply #2 on: September 11, 2018, 09:54:03 PM »
Different layers, different places on the print bed and different parts.  That's why I didn't think it was Slicer.

When I printed the replacement parts for the desk lamp was the first time I really noticed it.  Most of what I'm printing right now are more or less "proof of concept" parts so I don't really care about the surface finish on the part - within reason.  I was starting to wonder if there was something funky about the filament.

I think I'll continue to use this spool to print "test" parts where the finish doesn't REALLY matter.  I'm going to be printing parts for my RC Bruder CAT skidsteer and they need to be painted CAT yellow anyway.  I'll be switching to white filament then since it'll be easier to cover white with yellow paint than it will be to cover blue.

Don

Offline b.lindsey

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Re: Print layer failure?
« Reply #3 on: September 11, 2018, 11:45:19 PM »
Sound like some random anomolies in the filament then. Hopefully the white will do better.

Bill

Offline zeeprogrammer

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Re: Print layer failure?
« Reply #4 on: September 12, 2018, 01:18:34 AM »
Not that I'm an expert by any means...but I'm thinking it's the filament.
I've noticed when I get the 'same' filament from different manufacturers...it prints differently.
You should find settings in Slicer to adjust and account for it.
Problem is...you either have to find other people who've used it and use their settings or experiment.
Even when you use other people's settings, differences in the printer itself (or the controller - Pronterface?) can cause changes.
I suspect just the coloring can make a difference.
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Offline wagnmkr

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Re: Print layer failure?
« Reply #5 on: September 12, 2018, 12:18:26 PM »
Is it possible that the filament is not coming off of the spool easily, causing the extruder to not get enough filament at times. This has happened to me from time to time.

Also, after many spools through the printer, I find that there is a difference in quality between makers, so I stick to basically one brand now.

Hope you sort it.

Cheers

Tom
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Offline ddmckee54

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Re: Print layer failure?
« Reply #6 on: September 12, 2018, 07:10:24 PM »
A little more background information.  I've got a Prusa I3 clone with a Bowden tube extruder drive and supposedly an E3D V6 hot end.  It's actually a V5 clone, found that out when I ordered spare V6 hot end parts and they didn't match what I had.  I did some digging on the E3D site and found that the specs for a V5 matched what I had.

I think I may have a combination of at least three problems, two of them I may have caused:

1 - Trying to print the solid infill too fast.
MYBAD.  This speed was set at 60mm/sec., I've since dropped that to 50mm/sec, about 80% of the original speed.  When I would temporarily drop the federate to about 80% the popping would go away.

2 - Aligning my layer start points.
MYBAD AGAIN - MAYBE.  The nozzle used to have a drooling problem, so I set this variable in Slic3r to "Aligned" so all of the "zits" that needed to be cleaned off were in one location on the print - usually a corner.  I have since found the sweet spot for retraction, wiping, and the nozzle clearance height and I'm going to try randomizing this location again.

3 - Possibly inconsistent filament diameter.
I have noticed, at least with this spool of filament that periodically, especially when it's printing a solid infill layer, there are times  when the extruder drive gear will start "popping" and the filament appears to jump.  I'm guessing that MAYBE at that time the filament diameter has increased and the extruder is trying to melt more  plastic than it can handle?  Since I've got a Bowden tube setup, there's NO way that I can measure the filament diameter at the extruder when this happens.  When it does this "popping" the surface of the part is noticeably "different".  I'm guessing that the since the drive gear isn't putting a consistent pressure on the filament that the extruded filament width is changing.  I think it's being stretched thinner since the pressure on the filament into the extruder has been released.  If this occurs in the middle of a solid infill layer that MAY account for the rippling that I observed.  I have also observed that sometimes there is a gap between the perimeter layers and the infill layers.  If this "popping" occurred at the layer perimeter start point then the extrusion start point would not get a solid anchor leaving an air gap until the perimeter turned a corner of crossed another perimeter.  None of the following layers would have anything that they could bond to leaving a gap between the perimeter layers and the infill layers, sound plausible?

Like I said, I'm going to use up this spool printing prototype parts where I don't really care about the surface finish.  If I get ambitious I may chuck a different spool of filament in and try printing the same G-code file to test the bad filament theory.

Don

 

Offline zeeprogrammer

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Re: Print layer failure?
« Reply #7 on: September 12, 2018, 08:15:00 PM »
Interesting ideas. I'll be interested in what you find.
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Offline wagnmkr

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Re: Print layer failure?
« Reply #8 on: September 13, 2018, 11:49:06 AM »
Your theories sound good to me as well. I have read many stories of E3D clones acting the way you describe, and Bowden cable type feeds can apparently get "sticky". I did get all E3D stuff for my Wanhau, but then didn't get around to putting it on.

I hope you can get the trouble sorted.

Tom
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Offline ddmckee54

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Re: Print layer failure?
« Reply #9 on: September 13, 2018, 05:15:20 PM »
Well, I believe that I have found the "smoking gun", and I appear to be holding it.

Background information and approximate timeline.

I'm printing with Wyz Works blue PLA in 1.75mm, was at about 195-200C.  Prior to this I was printing with Wyz Works white PLA in 1.75mm at about 210-220C.  Both were printed at about 60mm/sec, a 0.2mm layer thickness and with the same 0.4mm nozzle.

The LAST thing that I printed in white was a new filament cooling fan shroud.  You know, the white one with the annular discharge ring, the one that I eventually determined WASN'T working.

I changed the fan shroud at the same time that I changed to the blue filament.  I was trying to print the trigger group parts for my Walther's PPK rubber band gun using my previous Slic3r and temperature settings.  These are smallish parts, 20mm across or less, and they turned in molten piles of goo.

I ASSUMED that this PLA needed to be run at a much lower temperature.... and I believe that at this point we were off and running with my present problem.  I could not get quality parts to print, no matter how much I messed with the Slic3r settings.  Other than dropping my extruder temperature down to about 200C so things didn't turn into molten piles of goo.

Fast forward to now, last night I was able to make A part with acceptable quality.  I did 2 things, I cranked DOWN the print speed and I cranked UP the extruder temperature.

I printed out one of the frames for the track rollers last night.  It took about 1 hour and 45 minutes-ish.  By the time it got done, after several tries, I was getting an acceptable finish on the part and the extruder drive gear was no longer popping.  I'm going to transfer those speeds and temperatures into Slic3r tonight and see if it can make a good part without any outside intervention. (I also bit the bullet and ordered a copy of Simplify3D.  We'll see if it's actually worth the cost.)

I'm also going to try tuning the extruder heater PID loop.  I wasn't happy with the way it was responding - took too long to react in my opinion.  I do this kind of crap for a living, but this is the first time I've tried to tune a loop through g-code.  I was never able to get the version of Marlin that came with my printer so I don't want to just dump something into it - never can tell what I'd break doing that.  I think I can modify the PID using the M301 command, I'll give it a shot and see if it works.

Don

« Last Edit: September 14, 2018, 05:37:14 PM by ddmckee54 »

Offline ddmckee54

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Re: Print layer failure?
« Reply #10 on: September 14, 2018, 05:59:07 PM »
Good news, the M301 command DOES work with my version of Marlin, so I can modify the PID settings in the initialization g-code.

I used this same g-code initialization trick to correct my X ,Y , and Z steps/mm scaling problem with a different M code command.  This way it doesn't matter what the Eeprom settings are, I change them to what I want every time I load a g-code file.

I made the Slic3r setup changes and printed a 20mm test cube, it seemed to work OK.  I also did this to verify that the default PID settings had indeed been modified by the M301 command, they had.

I then tried to print the other half of a previously printed part the "popping" still occurred, but not nearly as bad as before.  I slowed the feed rate down again and the rest of the print was made without further operator intervention.  I think we have a winner here.

Bottom line:
I changed the solid infill feed rate setting from 60mm/sec. to 45mm/sec.
I changed the extruder temperature from 200C to 220C.  (My machine always has liked the high end of the PLA range for some reason, whatever makes it happy.)
I'm tweaking the extruder heater PID settings to get a faster response to a temperature drop.  (This will be on-going for a while.)

I've got another spool of a translucent blue from a different manufacturer that I could never get to print properly.  If memory serves, and it doesn't always, I tried it right before I tried the current Wyz Works blue.  Hmmm....

Don
« Last Edit: September 14, 2018, 06:04:50 PM by ddmckee54 »

Offline Admiral_dk

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Re: Print layer failure?
« Reply #11 on: September 14, 2018, 08:18:56 PM »
Nice to hear that you found the solution  :cheers:

Offline ddmckee54

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Re: Print layer failure?
« Reply #12 on: September 17, 2018, 08:19:39 PM »
Good news, Bad news, bad news first.

I spent the weekend trying to get a successful test print of the transmission/motor mount for my Bruder tracked skidsteer project.  I thought that I had the problem solved, not so much.  I tried everything I could think of, along with any options suggested to me by others, and still the problem persisted.  The extruder gear would start popping and the filament size would be inconsistent.  It would still happen at any time, any location.

The GOOD news is that I solved the problem, I QUIT using the blue PLA.  Sunday afternoon I threw in the towel and changed the filament, purged out most of the blue filament from the hot end and ran the same print file again.  4 hours later I had a usable part, even if it is tinted with a little blue.

I'm going to check with Wyz Works and see if anybody else has had problems with this particular batch of blue PLA.  I'm not going to hold my breath, but maybe I can get a replacement spool of filament out of this.

Don