Weirdest print problem I've ever come across..

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superhornet59
Posts: 60
Joined: Wed Apr 03, 2013 1:58 am

Weirdest print problem I've ever come across..

Post by superhornet59 »

Okay.. so I've got a really weird problem that just started happening recently.. I can't explain it, heck, I'm not even sure I know how to describe it, so I've attached a photo:
DSC_0096.jpg
DSC_0099.jpg
I've googled around and found nothing. It's got me completely baffled.. I tend to be pretty good at troubleshooting, but the fact that this happens randomly during the print then randomly corrects itself, and the fact that it leaves this sort of repeating diamond pattern just blows my mind. It's like.. crop circles or something. The craziest thing is that these prints have very little in common.

Generally when trying to isolate the problem, we try to find a common condition what could be the root of the problem for all the parts.. so I just want to start by eliminating a number of factors now, because I changed them and the problem persisted.

Temperature: 195 for one of the round objects, 205 for the other, 195 again for the linkage
Slicer: Cura 13.04 (same exact g-code run twice) for the two round objects , slic3r for the linkage
Extruder tensioner: Prety tight at first, but tightened to the practical limit *after* one of the two round objects was printed
Extruder motor po: undervolted for the first two, raised back to default for that last.
Perimeter print speed: 25 mm/s for the two round ones, 35 for the linkage, externals both around 60% of that
Wall thickness: round ones are thin, linkage, not quite as much
Support material: round ones had it, linkage didn't

The factors that stayed the same:
Bed temp 55 degrees
Filament. Same black PLA from the web shop.. never had problems with it before though.
Layer height: 100 microns. Never had problems with it before either. Cura does 50 micron skin though, and slic3r does infil every 3 layers. So not identical either.
"filament settings". For some reason, since getting the printer, I never had perimeters bond together properly until I changed filament diameter to around 1.55mm and nozzle to around 0.32mm. Before that, layers would come apart. I first started printing on ABS and didn't have the problem, it came up when I switched to PLA.


Other weird notes: if I extrude filament in mid air, it often sharply curls back upward. I use a sponge dust filter, have only had the printer for 2 weeks, and have reassembled and cleaned it once because it was loose and leaked liquid PLA. Didn't see any clogs. I gently poked the hole with a sewing pin, but I've done it rarely and since I pretty much got the printer, with no resulting problems at that time.


No changes were made prior to printing these latest parts.. the parts that came before them were similar and printed fine.

Also, after I notice this problem, I try immediately manually extruding off to the side, and it's pretty weak. I pull out the filament, it's not grinded. No grinded filaments on the extruder wheel either. Also when the hot end heats up, plastic sort of slowly extrudes on its own... is that normal?


If you read all that, thank you, and enjoy the hunt! :)

satoer
Posts: 436
Joined: Mon Oct 01, 2012 8:00 pm
Location: Netherlands

Post by satoer »

Looks like a dirty nozzle to me. Are you sure the sponge cleans the fillament thoroughly?
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superhornet59
Posts: 60
Joined: Wed Apr 03, 2013 1:58 am

Post by superhornet59 »

That would make complete sense to me if the whole part was messed up, but I don't understand how that could result in such long intervals of good/bad.. the sponge I use is great, it collects so much dust after a long print that it's hard to believe anyone could print at all without one!

satoer
Posts: 436
Joined: Mon Oct 01, 2012 8:00 pm
Location: Netherlands

Post by satoer »

There's probably a bit of contamination in your nozzle. This will block the nozzle output a bit (the bad layers of your printed part) until it gets flushed out and print normally again (the good layers). There are several solutions to overcome this. First you need to clean your nozzle. Don't use a needle (!). Needle's don't fit in the 0,35mm hole and the stronger steel will damage the soft aluminum. I use guitar strings with great success thanks to a tip from someone on this forum. Secondly, use a dust sponge to clean the fillament from dust before it enters the exrtuder. Dust does not melt in the nozzle and will clog the nozzle eventually. But since you've done that, there are more thinks you can do. If the flow of fillament gets blocked in the nozzle, this also means the fillament slips from the toothed gear / bearing. Give the bearing a good tension, and try to adjust the extruder stepper motor power potentiometer to it's maximum power before overheating. This will press the fillament in with more force so any contamination will pressed trough.
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superhornet59
Posts: 60
Joined: Wed Apr 03, 2013 1:58 am

Post by superhornet59 »

Thanks for your in-depth response satoer :)

I'll try the guitar string method. Other then that, like I noted in my original post, I already tightened the extruder to its limit and turned up the pot (it gets a little warm now, so I can't push it much further.)

I'll also try using an new, thicker sponge, and I'll report back. Cheers!

superhornet59
Posts: 60
Joined: Wed Apr 03, 2013 1:58 am

Post by superhornet59 »

Follow up:

I'm a pretty lousy scientist, and I like to change multiple variables simultaneously. Maybe I just like linear algebra, who knows :) In any case, I cleaned it with the guitar string, and it's hard to tell if it was dust or just filament that came out, but something came out. Next up... the pots. Okay, am I crazy, or are the pots on the Felix 2.0 board backwards (clockwise = lower voltage, CCW = higher voltage). Because I originally turned the extruder pot clockwise to get more power but that didn't help at all. I turned it much further, and it started skipping lots of steps. when I turned the pot CCW, I could eventually here almost a kind of 'buzz' coming from the motor. Fine tuning to the point just before buzz (plus the cleaning) resulted in good prints, I've printed a few parts now and haven't had any problem. Hoorah, now we can all learn from my mistakes! :)

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