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underextrusion during printing at random height

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Posted · underextrusion during printing at random height

I like Illuminarti's theory. A lot. It fits with what you see because Cura has the fan off for the first few layers and gradually turns the fan on (it also gradually speeds up the print).

This part appears to have no stringing issues - meaning it appears that there isn't much retraction going on. So I would recomend a little more heat and a little less fan. Also since the part is nice and large you might be able to do without the fan. Can you turn fans off or run at 50%? Also raise temp to between 210C and 230C. Those two things (220C and less fan) will probably be enough.

 

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Posted · underextrusion during printing at random height

Allright, good idea. Since i've recently made another fan duct, thought that it might solve this problem, but nothing changed. During another print, i've turned off my fan completely. Print settings are 40mm/s print speet and 195C.

CIMG3553

 

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Posted · underextrusion during printing at random height

Why do you print 190C? That's quite cold for PLA. I recommend trying 220C or 240C. Don't be afraid to try a little hotter.

 

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Posted · underextrusion during printing at random height

I would also advise printing with hotter temps. I never print anything at 190, the layers don't bond well, and it's too unreliable. I use 195 as the bare minimum, and only with certain filaments which flow really well. But I keep mostly in the 205-235 range, depending on the speed. Also, It saying 190C may not even be 190C. On my old hotend, the thermocouple was consistently off by a few degrees. Try checking it with a temp probe at the nozzle.

Take a pic of that custom hobbed bolt of yours, it may not be the source of the problem, but it may be contributing to it.

 

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Posted · underextrusion during printing at random height

I've partially fixed the problem. Spend a lot of time investigating, and found out that the extruder feeder hobbed bolt was not working as supposed to. So i've made a new hobbed bolt, now it works much better. Though very rarely, filament slips and after some time i can find some filament chips on the table below feeder mechanism.The feeder is tightened as much as i can, maybe i need very strong spring there? what do you guys use?

Anyways, i want some more opinions now. It prints way better than before, but i get horizontal lines on my prints. Check the attached pictures.

20140119 140533

20140119 135810

 

What could be causing this? I can think only that it's either Z stage (though those lines appears in random height, at least it seems to me) or the pulleys on the axis, i can't make the belts more tighter, because pulleys are excentric and it's already moving like easy > medium > easy >medium > .. so if i tighten belts more, steppers sometimes starts slippiing.

 

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Posted · underextrusion during printing at random height

... i get horizontal lines on my prints...

What could be causing this?

... because pulleys are excentric ...

 

Well, I think you answered by yourself :)

 

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