[Help] Extruding trouble

So, I just finished my Mendel Prusa i3 with catnozzle (0.4 dia), using Sav MKi

I've no idea what I'm doing wrong, if my hobbed bolt is tight enough, if I got the settings wrong or if I got an extruder jam.

I tried printing a test cube, I could only get the perimeter and 3 outer lines for each side on first layer. After that, it goes to infill, but doesn't extrude (...fast enough?).

The perimeter started as dots, then turned into a solid line. There is some space between each line on the actual cube.

If I try to extrude manually afterwards, it doesn't extrude at all, hobbed bolt just chips away the filament.
Also, filament drips out of the nozzle whilst nozzle is warm

I did this twice, emptying nozzle of filament in between (pushing it myself manually extruded the filament real nicely), both times ended up exactly the same.

First time I tried with 185C, second 195C, no difference. Also lowered the infill speed for second attempt, as I said, no difference.

Printing speed (mm/s):
Perimeter 20
Small perimeters 30
Infill 40
Travel (non-print) 130
First layer 30%

Infill: Honeycomb, fill density 0.4

Extruder
Nozzle dia: 0.4mm
Offset 0, 0
Retraction: length 1, lift Z 0, speed 30mm/s, min travel after retract 2mm, retract on layer change (true)

Using Slic3r and Pronterface

I'm a total newbie, so let me know if any additional info is needed.

Edited 1 time(s). Last edit at 11/04/2014 08:26AM by Sanzennin.

You are probably extruding to fast, lower extruder steps in your firmware. The extruder-motor wants to push more filament trough the nozzle as it can handle, causing a jam.

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Prusa I3 kits www.schufco.com

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Schufco
You are probably extruding to fast, lower extruder steps in your firmware. The extruder-motor wants to push more filament trough the nozzle as it can handle, causing a jam.

Hmm, you're probably right. But what setting should I change in firmware? The easiest-to-understand setting I have is e-steps, but that is steps/mm, not mm/s, and I don't see how printing less would fix my problem of not printing enough. On the software side, I did limit my speed to 3mm/s and that did work, for the first layer anyways. The second layer sped up because I didn't notice it had different settings. Well, lowering that to 3mm/s I think I might be able to print something alright-like.

I also increased my temperature to 200C, this seemed to help a bit.

Still, 3mm/s is extremely slow by any standard, could it be that there is just a huge gap between my thermistor and reality? Would that affect anything? Sure wish I had a laser thermometer.

I'll have to continue my experiments tomorrow, 3mm/s and even a cube of 15x15x5 (mm) takes 30 minutes or more.

3mm/sec is uncalled for.
Even 30mm/sec is slow for most.

" and I don't see how printing less would fix my problem of not printing enough."
Your are building up to much pressure in the nozzle, your hobbed bolt will chip away filament and looses its grip and won´t be able to push anything trough anymore.

Change following e-value in your firmware in configuration.h.
Do not take the value of the line below but manual extrude 10mm filament with your software and measure it on your extruder. Lower your e-steps value untill your extruder exactly feeds 10mm of filament.

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4075,105} // X, Y, Z, E

Restore your printing speed to at least 30mm/sec.

Edited 1 time(s). Last edit at 11/04/2014 05:30PM by Schufco.

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Prusa I3 kits www.schufco.com

Quote
Schufco
" and I don't see how printing less would fix my problem of not printing enough."
Your are building up to much pressure in the nozzle, your hobbed bolt will chip away filament and looses its grip and won´t be able to push anything trough anymore.

Change following e-value in your firmware in configuration.h.
Do not take the value of the line below but manual extrude 10mm filament with your software and measure it on your extruder. Lower your e-steps value untill your extruder exactly feeds 10mm of filament.

#define DEFAULT_AXIS_STEPS_PER_UNIT {80,80,4075,105} // X, Y, Z, E

Restore your printing speed to at least 30mm/sec.

Well, just to try it (this bugs me, couldn't sleep ^^), I halved my e-steps. Now attempting to extrude 10mm of filament, extrudes 5mm of filament, which according to the formula of ('asked for' / 'got' ) * 'current e-steps' would suggest I need to double my e-steps. Which would lead me back to the original value. So is there some other value I need to change as well to make it work?

EDIT: I repeated this multiple times, every time I get exactly half of what I asked for. And I monitored the movement of the filament, it didn't get stuck at any point, which would've reduced the length that I got.

Edited 2 time(s). Last edit at 11/04/2014 07:00PM by Sanzennin.

No where did you mention if you are using PLA or ABS filament. The temps you listed should be fine if it's PLA but they are way low if it's ABS.

Other possible things it could be, Bad filament full of junk (China stuff), Not enough pressure on the filament and hobbed bolt (slipping filament), poorly designed or built hotend or wrong thermistor type set in firmware so it's reading higher that it is (just try higher temp to see, go 220c). Also one thing that is hard to believe but are you trying to use 1.75mm filament in an extruder/hotend designed for 3mm?

Hope these help

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tmorris9
No where did you mention if you are using PLA or ABS filament. The temps you listed should be fine if it's PLA but they are way low if it's ABS.

Other possible things it could be, Bad filament full of junk (China stuff), Not enough pressure on the filament and hobbed bolt (slipping filament), poorly designed or built hotend or wrong thermistor type set in firmware so it's reading higher that it is (just try higher temp to see, go 220c). Also one thing that is hard to believe but are you trying to use 1.75mm filament in an extruder/hotend designed for 3mm?

Hope these help

Thank you for your input,

I'm using PLA, maker is "3D Ink filaments", I have no idea if that is "bad china stuff"? I couldn't find any negative reviews online.

I've tried tightening the hobbed bolt/idler way tight. How tight should it be normally? (When we are talking about hobbed bolt tightness, we are talking about idler pressing against the hobbed bolt, right?)

My hotend is catnozzle, it was pre-built. Do you know what would be the correct thermistor type setting in firmware? I think I might have that wrong, as when I tried extruding manually, set at 185C, I couldn't get any filament through (I was patient). 200C seems to work better.

The extruder and hotend are designed for 1.75mm afaik, it barely goes through. 3mm filament wouldn't fit. So I don't think that is the issue.

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Sanzennin
... Now attempting to extrude 10mm of filament, extrudes 5mm of filament...

I assume this is just a mistake with the sentence structure, but when calibrating the extruder, you are not measuring how much filament extrudes, you are measuring how much is pulled INTO the extruder. How much comes out is not considered as part of this calibration.

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jbernardis

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Sanzennin
... Now attempting to extrude 10mm of filament, extrudes 5mm of filament...

I assume this is just a mistake with the sentence structure, but when calibrating the extruder, you are not measuring how much filament extrudes, you are measuring how much is pulled INTO the extruder. How much comes out is not considered as part of this calibration.

Yes, that was just the sentence structure. Suppose it would have been clearer if I used the term "pull in"?

I just used a micrometer to measure the barrel size, it's definitely not a 3mm barrel, but over 2mm anyways. (My PLA is 1.75mm) However the guy who sold me says that's normal. How much larger barrels do you guys have?