extrusion multiplier and width question...

When I print a model with ABS and rectilinear-filled top/bottom layers, AND that has many long runs of fill, I end up with something like a banjo on the bottom layer. All other layers are fine.

The problem has persisted even after I reversed and redirected the HE fan airflow (which did significantly address warping problems).

I'm printing with the default MF extrusion multiplier and width settings. First layer HE temp is 240C, and 235C thereafter..., the bed is 110C on all layers. FWIW..., I have experimented with HE temps around 225C, but not much changed wrt this problem.

The default first layer extrusion width setting is "200%", and I'm wondering if "300%" might be worth trying.

If you have any thoughts to share regarding diagnosis and "cure"..., that would be great. Note: the photo pre-dates the HE fan reversal fix, so it exhibits the warping problem..., but the banjo problem shown has remained the same after the fix.

Attachment 6525

FWIW..., tried a first layer extrusion width of 300%. Made no real difference.

Might try closing down the HE to bed gap a bit..., though its already at the "lightly drag sheet of paper" point.

Oh wait! The x-carriage is loose..., umm..., and there's other stuff I've been wanting to fix besides. (and the HE/bed gap was waaaay wide for some reason...)

Alrighty then...

Hey lakester, I would make sure your bed and carriage both are not loose and that your belts have good tension. I do however think you are underextruding as well. Increasing to 300% or even going down to 100% (which is how I like to print) shouldnt change the issue you are having if you are indeed underextruding. This is because the slicer software takes the width into consideration and makes wider passes to adjust for the increased width. Also, the setting for increasing the first layer width only affects the first layer, looking at your photo, your second layer, and I am assumming the rest of your layers, are not touching as well. I stongly suggest increasing your extrusion muliplier (aka flowrate.) Do calibration prints increasing by 5% each time, once your layers are touching you can continue to fine tune by increasing/decreasing by 1%. Its amazing how much of an affect 1 or 2% can have when really dialing it in.

Hey!

Sorry..., I should've posted some follow-up. What happened afterwards I posted here:

http://3dprintboard.com/showthread.p...ll=1#post62965

The layers above the first layer were at least adhered to the successive layers, i.e., they were immobilized (top-bottom)..., so I didn't sweat it that much, though you are correct, it is indicative of a problem. Interestingly, by the time a top layer was reached, the filament had side to side adherence.

Ah..., I wondered if the extrusion width adjustment affected the tool path. Thx for confirming that..., cuz that's visually what seemed to be happening.

I'll admit that I was hoping that the extrusion width settings didn't alter the toolpath..., since that leaves only the extrusion multiplier..., which is a global setting. Buuuut..., I'll definitely give it a shot, especially since I've switched to PLA for a bit and I think I'm seeing symptoms that could be related to underextrusion..., though I'm also thinking I wish I could find a reliable way to clean the HE..., since I also think I'm seeing symptoms of gradually increasing flow restriction.

Anyways..., thank you! Have some more tuning to play with now!

Quote:

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Originally Posted by jheikkila54

Hey lakester, I would make sure your bed and carriage both are not loose and that your belts have good tension. I do however think you are underextruding as well. Increasing to 300% or even going down to 100% (which is how I like to print) shouldnt change the issue you are having if you are indeed underextruding. This is because the slicer software takes the width into consideration and makes wider passes to adjust for the increased width. Also, the setting for increasing the first layer width only affects the first layer, looking at your photo, your second layer, and I am assumming the rest of your layers, are not touching as well. I stongly suggest increasing your extrusion muliplier (aka flowrate.) Do calibration prints increasing by 5% each time, once your layers are touching you can continue to fine tune by increasing/decreasing by 1%. Its amazing how much of an affect 1 or 2% can have when really dialing it in.

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When it comes to adjusting the flowrate, you usually have to adjust this per type of filament and usually needs fine tuning between different rolls. For cleaning your nozzle, you can check out this artical http://bukobot.com/nozzle-cleaning I will use this when I think I am having issues. Also a good trick for PLA is to dip an inch of the filament in some olive oil and run that through your nozzle. Only need to do this once in a while, as this just "seasons" the nozzle to better prevent PLA from burning onto the nozzle, causing flow blockage. You do not need to do this when printing with other filaments, and is completly optional for PLA as well.

Also, make sure you calibrate your E steps, here is a guide to do this http://www.instructables.com/id/How-...ur-3d-Printer/

Do this before playing with the flowrate multiplier, as changing your E steps will change the amount of plastic extruded.

Ah. I had seen mention of the cold-pull technique on youtube, but didn't have the nerve to actually try it. I think it would be worth trying though, and then perform the seasoning step.

I've checked on several occasions and I seem to have lucked out in that the default Makerfarm e-steps config has been dead on.

FWIW..., I've been musing on the possibility that the extruder has been slowly becoming clogged. No real evidence to support that, and I may be misremembering my earlier experience with PLA, but it seems that with PLA now, it takes forever for a stationary extruder to stop oozing when at temperature..., making me wonder at the possibility of increased pressures and restricted flow. Also FWIW, I've noticed that slowing my PLA prints waaay down significantly improves print quality..., i.e., I don't recall having to run things so slowly for similar quality..., but to be honest, I'm printing very different things than I was, which may demand the slow down anyway.

Thx!

Quote:

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Originally Posted by jheikkila54

When it comes to adjusting the flowrate, you usually have to adjust this per type of filament and usually needs fine tuning between different rolls. For cleaning your nozzle, you can check out this artical http://bukobot.com/nozzle-cleaning I will use this when I think I am having issues. Also a good trick for PLA is to dip an inch of the filament in some olive oil and run that through your nozzle. Only need to do this once in a while, as this just "seasons" the nozzle to better prevent PLA from burning onto the nozzle, causing flow blockage. You do not need to do this when printing with other filaments, and is completly optional for PLA as well.

Also, make sure you calibrate your E steps, here is a guide to do this http://www.instructables.com/id/How-...ur-3d-Printer/

Do this before playing with the flowrate multiplier, as changing your E steps will change the amount of plastic extruded.

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