Prusa i3 intermittent extrusion
October 21, 2016 07:16PM
Hi, I'm new to the forum and in the world of 3D printers. First of all sorry for my bad English.

I just set up a Prusa i3 and is perfectly calibrated, the problem comes when printing for a few seconds and then stops printing materials extrude and again start printing...

Here you have a picture of the result. I've tried changing the settings, bed and extruser temperatura, the nozzle diameter (less diameter to extrude more filament), manually modify the current with potentiometer pololu, reduce all print speeds ... I can only set so that the amount of filament is greater but I do not know how. Any solution? Thank you.




Re: Prusa i3 intermittent extrusion
October 21, 2016 07:25PM
What size nozzle are you using?


Out of the box thinking is easier when you never fitted in the box to begin with. smiling smiley
Re: Prusa i3 intermittent extrusion
October 21, 2016 07:30PM
nozzle 0,4 mm
filament PLA 1,75 mm
Re: Prusa i3 intermittent extrusion
October 21, 2016 07:37PM
What temps are you using?


Out of the box thinking is easier when you never fitted in the box to begin with. smiling smiley
Re: Prusa i3 intermittent extrusion
October 21, 2016 07:40PM
Most PLA should print well between 180c and 220c.
Do you have your fans on while printing?


Out of the box thinking is easier when you never fitted in the box to begin with. smiling smiley
Re: Prusa i3 intermittent extrusion
October 21, 2016 07:50PM
I have tried 200 and 220, and fans always on
Re: Prusa i3 intermittent extrusion
October 22, 2016 02:02AM
What extruder system are you using?


Out of the box thinking is easier when you never fitted in the box to begin with. smiling smiley
Re: Prusa i3 intermittent extrusion
October 22, 2016 06:09AM
Quote
Rlewisrlou666
What extruder system are you using?

I don't know what do you mean with "Extruder system" but I have a MK8 extruder, the 3D printer is a Prusa i3 ProB from Geeetech.

Edited 1 time(s). Last edit at 10/22/2016 06:09AM by Pelle13.
Re: Prusa i3 intermittent extrusion
October 22, 2016 08:10AM
Is it direct drive, Bowden, wades?

Are you getting any unusual marks on your filament like stripping or anything.


Out of the box thinking is easier when you never fitted in the box to begin with. smiling smiley
Re: Prusa i3 intermittent extrusion
October 22, 2016 08:20AM
I have news!
I don't know what you mean with direct drive, Bowden or waves... But the filament is perfectly smooth.

I tried to print a 20x20x20 cube and this the result is awesome:

TOP:



BOTTOM:




The bottom and the top isn`t acceptable but the body is perfect!
This is with 0.2 layer height, when I put 0.4 layer height (to get faster printing) It's again a disaster... ¿Any solutions?
Re: Prusa i3 intermittent extrusion
October 22, 2016 08:50AM
Bad news... Anything else I print with 0.2 layer height still being a disaster...


Re: Prusa i3 intermittent extrusion
October 22, 2016 08:51AM
Your first layer is WAY too high off the build plate.
Re: Prusa i3 intermittent extrusion
October 22, 2016 09:01AM
Quote
Floyd
Your first layer is WAY too high off the build plate.

Layer height 0.2
First layer height 0.35

Should I change First layer height to 0.2?
Re: Prusa i3 intermittent extrusion
October 22, 2016 09:49AM
Heat up your printer, remove filament, and clean your nozzle. Move to the center of your bed. Move a few mm up from the bed, then move down until the nozzle barely touches the bed. You should be at Z = 0,00mm.

From the pictures though it looks like underextrusion
Re: Prusa i3 intermittent extrusion
February 19, 2017 11:46AM
Geeetech uses the cheapest, crappiest plastic extruder head. Just take a look at the geeetech forum complaints about under extrusion.

If its the mk8 plastic extruder head check the tension of the arm, if the spring is weak, add shimies to compress it more. If its the heavy duty spring, dissassemble the extruder head and examine for cracks. Mine came with a heavy duty spring which had put so much force on the idler wheel it had cracked the part holding the axle. The part was hidden between the stepper and the tension arm so i didnt diagnose it for a long time. Ive removed some of the plastic which sets the gap to give enough tension even with the cracked part while i wait for a new metal extruder head.

This problem really sucks because there are so many legitimate problems which can cause your problem you can spend forever following those without realising the product is faulty by default.
Re: Prusa i3 intermittent extrusion
February 20, 2017 03:51AM
Quote
ethicalfive
Geeetech uses the cheapest, crappiest plastic extruder head. Just take a look at the geeetech forum complaints about under extrusion.

If its the mk8 plastic extruder head check the tension of the arm, if the spring is weak, add shimies to compress it more. If its the heavy duty spring, dissassemble the extruder head and examine for cracks. Mine came with a heavy duty spring which had put so much force on the idler wheel it had cracked the part holding the axle. The part was hidden between the stepper and the tension arm so i didnt diagnose it for a long time. Ive removed some of the plastic which sets the gap to give enough tension even with the cracked part while i wait for a new metal extruder head.

This problem really sucks because there are so many legitimate problems which can cause your problem you can spend forever following those without realising the product is faulty by default.

I bought one of this and still happening but less...


Edited 1 time(s). Last edit at 02/20/2017 03:52AM by Pelle13.
Re: Prusa i3 intermittent extrusion
February 20, 2017 03:58AM
You could try oil lubricating the filament. Since I started doing that it seems to help the filament move more freely. Ive been getting my cracked extruder head to push filament by prelubricating. Also if i go over 240 for my ABS heat creep causes the filament to clog inside the heat break. Thats bad news for me.. i was excited to replace the extruderhead when it arrives.
Re: Prusa i3 intermittent extrusion
February 20, 2017 06:10AM
Thats a nice extruder,exactly what i use. Make sure you adjust the tensioner bolt so that the brass toothed wheel bites into
the filament enough so it does not slip.
Heat the bed and nozzle,then move the nozzle to centre of the bed and at Z0 you should have about a 'fag' paper distance between nozzle and bed(adjust Z home if nessesary)
With layer height set at 0.2mm, set initial layer to 0.3 or 0.35 and initial extrusion width to about 130% (set in the slicer)
I find printing circles on 1st layer can be problamatic at times and need to be printed quite slow(10 -20 mm/s seems to work for me)
Re: Prusa i3 intermittent extrusion
February 20, 2017 10:00AM
Quote
obewan
Thats a nice extruder,exactly what i use. Make sure you adjust the tensioner bolt so that the brass toothed wheel bites into
the filament enough so it does not slip.
Heat the bed and nozzle,then move the nozzle to centre of the bed and at Z0 you should have about a 'fag' paper distance between nozzle and bed(adjust Z home if nessesary)
With layer height set at 0.2mm, set initial layer to 0.3 or 0.35 and initial extrusion width to about 130% (set in the slicer)
I find printing circles on 1st layer can be problamatic at times and need to be printed quite slow(10 -20 mm/s seems to work for me)

But I saw when the motor made the noise and I think that it isn't slip, I think is the motor that loose steps... I will try to change the voltage in the pololus.
Sorry for my bad english.
Re: Prusa i3 intermittent extrusion
February 20, 2017 06:32PM
One other thing. You should not change the nozzle size in you slicer. It should stay set to the size you are using.

What you need to change in the slicer to help get good extrusion is the diameter of the filament. This is only nominally the specified size. You need to take sample measurements of the actual filament you are using and feed the average value into the slicer. This WILL almost certainly differ from reel to reel, just as the best printing temperature does. Write them on a label and stick it on the reel.

Oh and just another point, do you have you slicer set for solid top and bottom infill? If not then it will use the general infill percentage that is set.
Re: Prusa i3 intermittent extrusion
March 01, 2017 08:58AM
Do you have any hairspray or Prittstick on the bed?
Re: Prusa i3 intermittent extrusion
March 02, 2017 05:57AM
Quote
SargFowler
Do you have any hairspray or Prittstick on the bed?

Yes, hairspray and the bed temperature is 55ºC
Re: Prusa i3 intermittent extrusion
March 02, 2017 06:48AM
Are you printing PLA?

Looks to me like heat creeping up the hotend, thus blocking the Filament path. if preasure gets high enough blocking is pressed throu - just for next blocking to take place.
How Long are your Retracts? - to Long retracts cause the same Problem.

can you give us a Picture of your complete hotend (the "printhead")? - would be easier to help.
Re: Prusa i3 intermittent extrusion
May 12, 2017 03:13PM
Hi,

I have the exact same problem with a Geeetech pro B too.
Did you find a solution?

I think the force required to push filament into extruder is harder than before and so, gear used fanally rip.
That should be reason why increase spring tension helps.

I really think there is another solution than increase spring tension. I think that first time I used it I was able to push filament with less force.
Re: Prusa i3 intermittent extrusion
May 13, 2017 02:40AM
Quote
Pelle13
Bad news... Anything else I print with 0.2 layer height still being a disaster...


That's happened because your nozzle height, that's why the cube has a bad first layer, use hairspray and first layer print with no fan bed at 60 then drop bed temp after 2-3 layers to 50,turn layer fan on 2nd layer.its critical you get your nozzle distance correct as the above picture looks to me there is flow but not sticking to the bed and it just moves the plastic around the build space,


Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]
Re: Prusa i3 intermittent extrusion
May 13, 2017 03:29AM
Hi, in my case, first layer perfectly stick, but get "waves" like in the first post
Re: Prusa i3 intermittent extrusion
May 13, 2017 06:22AM
Quote
tototutu76
Hi, in my case, first layer perfectly stick, but get "waves" like in the first post

Hi friend, I will try to help you.
Have you tried to...
1) increment the pololus voltage? (only for the extrusor step motor)
2) strech the extrusor's spring?
3) increase temperature?
Re: Prusa i3 intermittent extrusion
May 13, 2017 04:44PM
Hi,

Thanks for your help.

I already tried option 1(increase polulu) and 3 (higher temperature)

About option 2, I can't understand why does it worked before and not anymore (don't know if a spring like this can loss tension).
I saw someone added a spacer to get higher pression.

You switch to an aluminum structure, That allows stronger spring. did that solved your problem?
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