Strange blobbing/gaps...

[Qdeathstar]

Lately I been experiencing these lines/zits on my prints.. That seem to happen one one side or the other of the print at random, and if I'm printing multiple objects at the same time, the zits still appear, but they'll be on random layers (eg, not all the same layer)

So far I've tried cleaning the nozzle by removing it from the hot end and soaking in abs/torching it... It's compleaty clean and that seemed to help filament flow, but not this problem.

I've also tried lowering retraction speed but didn't seem to make a difference at all. Any ideas?

[Qdeathstar]

I did check for slop in the belts... I can move them out about 3/4" but they snap back into place so I guess they are tight enough..

[joe]

Looks like you are under extruding in those areas. Does the bad layer continue through part on the same plane? You may have binding in the filament path. You may have fluctuating nozzle temperature. Your extruder stepper may be getting excessively hot on the Rambo, check the fan on the back of the board is working.

[Qdeathstar]

Actually,

now that you mention it maybe i do have fluctuating nozzle temp.. right now my rambo says the nozle is at 227 even though i have it set for 233.... while i was typing that it jummped to 233 again. (EDIT: looks like it occilates between 222 and 233...
Maybe a pid autotune is in order?

[Qdeathstar]

Hi,

I gave that a shot... the temps stay at around 233 now but.... still have the issues in the picture. I think i might need to change how my extruder is mounted.... I moved it too the top of the rostock for my enclosure, and there is a pretty tight radius bend at the top... (although it seems like the filament extrudes fine, i dont here the tale tale click).....

[Qdeathstar]

I'm almost certain this is an underextrusion issue. I just wanted to check my e-steps because when i look at my build plate there are huge gaps in the first layer... it was at 467.4 but on the bondtech website it shows that the QRv2 should be closer to 490.... I got 476.4 from calibrating a while ago, and it seemed to work fine for a while so i'm not sure why the sudden change, except that I recently switched from using matter control to simplify3D...maybe matercontrol was over-riding the e-steps value with something else?

(i'm using the mattercontrol tablet as a MQTT server for a project i'm working on)....

[Xenocrates]

I'm almost certain this is an underextrusion issue. I just wanted to check my e-steps because when i look at my build plate there are huge gaps in the first layer... it was at 467.4 but on the bondtech website it shows that the QRv2 should be closer to 490.... I got 476.4 from calibrating a while ago, and it seemed to work fine for a while so i'm not sure why the sudden change, except that I recently switched from using matter control to simplify3D...maybe matercontrol was over-riding the e-steps value with something else?

(i'm using the mattercontrol tablet as a MQTT server for a project i'm working on)....

It's much more likely that the filament diameter (Or the setting for it), has changed, or the extrusion multiplier has. the firmware has control over the E-steps value, not the slicer, but it will move the commanded distance, which the slicer does control.

[Qdeathstar]

I have no idea what I did, but I have seriously f* something up... More pics:

[img]http://s14.postimg.org/uge6beh4x/image.jpg[/img]
[img]http://s14.postimg.org/neku2y2wx/image.jpg[/img]
[img]http://s14.postimg.org/8wnmuyblt/image.jpg[/img]
[img]http://s14.postimg.org/foe1xt0ld/image.jpg[/img]
[img]http://s14.postimg.org/bgj9p1z5t/image.jpg[/img]
[img]http://s14.postimg.org/g3pbqtmip/image.jpg[/img]
[img]http://s14.postimg.org/7zh7m303l/image.jpg[/img]
[img]http://s14.postimg.org/m76waqcsh/image.jpg[/img]
[img]http://s14.postimg.org/5xgq7u24h/image.jpg[/img]
[img]http://s14.postimg.org/q643tk1fl/image.jpg[/img]
[img]http://s14.postimg.org/8u3r847y9/image.jpg[/img]

[Qdeathstar]

I also printed a calibration test.... The circle cut out is more like an oval....

[img]http://s18.postimg.org/ukam0z9k9/image.jpg[/img]
[img]http://s18.postimg.org/n5la8lnop/image.jpg[/img]
[img]http://s18.postimg.org/9py9j5f6x/image.jpg[/img]

[joe]

You have clearly offended the great 3D printing gods. I am sure XENOCRATES will be here soon to write a book about it.

[Qdeathstar]

I'm doing the same calibration print now, with literally nothing changed except my enclosure heater isn't on and the print is looking (not perfect but) significantly better??


Printing in abs via sd card

[Qdeathstar]

Pics of the last print (bottom print is newest print, top print is last night)

[img]http://s11.postimg.org/xut1oo577/image.jpg[/img]
[img]http://s11.postimg.org/qsv42h1lf/image.jpg[/img]


Last night:
[img]http://s11.postimg.org/8ekkyhpar/image.jpg[/img]

Now:
[img]http://s11.postimg.org/z0x1ngthv/image.jpg[/img]

note the lack of blobbing on the bottom and top of the square....

[Qdeathstar]

I *may* have found the issue... I was checking to see if my thermistor/heating element was tight (to see if there was a temperature problem) and when i pushed on the thermistor lug the whole hot end twisted, so i guess when i was unclogging it I never got it tight enough... I have tightend it up and im reruning the calibration print...

[Xenocrates]

You have clearly offended the great 3D printing gods. I am sure XENOCRATES will be here soon to write a book about it.

Ouch, the snark is strong with you.

Anyways, it looks like a lot of the problems were reduced when you didn't have the chamber heater on, which for ABS seems contralogical. However, it appears your problems are primarily with retraction/extrusion, and overhangs/bridging. So I suggest you take an average of the filament diameter for 7 spots in two meters, and then try it again a few meters further into the spool and see how well they match your set number, and that you enable part cooling fans, especially for bridging, but you keep them relatively low, and tweak that cap percentage as you go. That should solidify the plastic you lay down faster and keep it from drooping, which is the source of the majority of the blobs in the calibration print, and let you turn the chamber heater back on to reduce warping.

[mhackney]

If the chamber heater is using the same power supply as the printer it *could* be taking away current and cause some problems. This also looks like the part cooling fan was either not used or not very effective. A good directed stream of air would "freeze" the ABS and reduce those blobs a lot.

What happens if you rotate the part 90° and print it? Does the elliptical shape follow the rotated direction or stay the same relative to the printer?

[Qdeathstar]

Thanks for everyone's suggestions. I will be trying all of them. I didn't know abs should still have active cooling.. I took the fan off because I got tired of it hitting my enclosures and making my belts grind..

I'm going to try a berdair for that since it won't stick out any and I can take air from outside the enclosure...

I'm heading home now so I can try some of these suggestions.. Thanks everyone.

[mhackney]

It's all a balancing act. Too much cooling like most people do can cause problems. I use a soda straw to direct a stream of air precisely. Never had a problem with cooling ABS.

[Qdeathstar]

My prints have been improving. I think I'm going to have to add cooling before troubleshooting this much further, but at least the zits are improving.. My latest part only has them in places with overhang.. So that's probably because the abs is curling from being too hot

I did the 10mm cube retraction calibration and lowered my retraction from 6mm to 4.7mm... And I measured my filament and I get 1.71mm (but I already had that set up).


I'm printing the original thing I wanted printed now, and at about 50 percent I don't see any zits...

Once I get my cooling set up I'll rerun the test print and see what happens...


Btw, the oval shows up no matter which way I print... (Well, I tried with the peice between x and y tower, then straight out from z) This is strange because I know I have been able to print round circles before....