Strange extruder feed problem Prusa i3

Been so happy printing all sort of stuff now for a while. Today I started printing an object with size 70x120 mm
Most other stuff I printed was not bigger than like 30x30 mm
What I found was that when printing the first layer the freakin extruder feed stopped advancing filament ....
Trying lot's of times with this big surface and then with smaller surfaces it just seems I have no good feed for the first layer
With small objects feed is all fine once you get past first layer
Gussings:
First layer is with lower feed rate on extruder what I can see ....
That's not workin on my printer. Just never noticed since all went fine after first layer with smaller objects
Now, with this bigger surface maybe the bad feeding get time to rally eat into the filament so it won't even work on second layer.

Cleaned up my feed bolt. Tried harder or looser tension on the wheel that press on filament ....
No way I get it working Only thing I can think of for some reason I get bad extruder feed at very low feed speed ....
If I do manual feed after failure it's all good once I push it a little to get paste the eatin in on the filament that get it all stop working.

Anyway, if this ring a bell for anyone I would be real glad to get some help on this one
So weird it's working totally good for smaller objects ...... only thing I can guess is it has to do with that it feed for a longer time at slower speed with this bigger one.
Once it get stuck I can't force it like I do afterwards to get it going again with manual feed ....
Changing pressure on the clamp/roll that press on the filament is the only thing I can think of for adjustment .... but no luck with that

Ha det gött
Bosse

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

Is the motor got enough torque i had similar issues i tuned up the amps on my motor but also check your hotend it may need a good clean

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Check my rubbish blog for my prusa i3

up and running
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Quote
chris33
Is the motor got enough torque i had similar issues i tuned up the amps on my motor but also check your hotend it may need a good clean

Thanks Chris. Motor should be ok. I see the motor and feed wheel turning as they should ... just not filament going forward.
M, cleaning extruder. Could be. Have to google that.
Took out the feeding bolt and cleaned it good from any little filament clogging.
Testing further now doing manual feed. At also slower speed like 50, 25 mm/min (my default is 100)
That all was good .....
But printing still get fail on feed after a while ..... now also for smaller objects
I'll go for cleaning hot head ... only explanation I can see
Ha det gött
Bosse

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

Hm, had a look at a vid howto clean nozzle/extruder. Seems you need a burner to do that proper. Burn any plastics out .
Bit complicated ..... Also I wonder why I can manual feed "for ever" after print fail.
Just push a little on the filaments to get it started. So is cleaning really gonna help ??
Still .... only other idea I have is if there is some irregularity on the notches for feeding bolt ....
That somehow not disturb at manual feed but more when printing .... depending on how feed goes for forward and retract.
Think I'll get a spare bolt just try that out ..... while I'm pondering on how to do cleaning of extruder parts.
Ha det gött
Bosse

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

Okiee. This problem is bringing me into la la land
Some more findings:
I tightened the spring press totally on the filament feed. Springs totally contracted and 4-5 full turns also after that.
This solved the problem for smaller parts. All good there now.

Then I started on my big 70x120 mm print again.
Same like before, after some 10 % of first layer stopped feeding plastic. This time I discovered the Pause button in Repetier he he
Did Pause, raised head, manual feed 10 mm while gently pushing filament down. Feeding ok.
If I push down real hard on filament while stuck feed and still printing it does NOT help at all to get it going.
Did Continue and now it's feeding good for some time.
At like 40 % of layer 1 stopped feeding again.
Pause, manual feed (worked even without pressing plastic down)
Continue and feeding good
At like 50% of first layer suddenly I get uneven output ....
Very thin / full layer height (se attached pic )
Then second layer starting that print and feed was almost toatal good. No stop in feed.
Layers after that just print all good and normal. No feed problem ......

So my conclusions questions:
First layer is printed at half head speed and half feed rate. Not sure why but I guess that is part of my problem.

The uneven printing of last half of 1st layer .... only idea still it might be nozzle/extruder clogged. Since while this happened, plastic feed was doing normal.
Just can't figure out why it hits only for 1st layer on big first layer area .....
I did got the big object finished. Just not acceptable workaround to do Pause/manual feed to get going.

Any idea on the problem will make me happy

Thanks
Ha det gött
Bosse

Edited 2 time(s). Last edit at 06/30/2014 04:56PM by sidhabo.

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

it may be that your glass is not 100% flat, or your bed is not completely level. this causes the first layer gap to close up and jams the hot end. Check the z height with the bed and hot end at temp at several different spots, every 10 mm or so. you may need to adjust your first layer up a bit.

Quote
cat.farmer
it may be that your glass is not 100% flat, or your bed is not completely level. this causes the first layer gap to close up and jams the hot end. Check the z height with the bed and hot end at temp at several different spots, every 10 mm or so. you may need to adjust your first layer up a bit.

Thanks for feedback CF. Can't detect any obvious diff in glass level over that area and all good level in the 4 corners. Will do some more testing now with different area size test objects. Maybe the problem is with the stl file for my big object ... ???

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

I would look at the level of the bed i use auto bed leveling system and i have seen 100% improvement in get the 1st layer down since i implemented it

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

Quote
chris33
I would look at the level of the bed i use auto bed leveling system and i have seen 100% improvement in get the 1st layer down since i implemented it

Oki, I'll try that. But that will only take care of getting like the 4 corners to be balanced yes ?
Won't take care of any possible warp of the glass itself ?
Ha det gött
Bosse

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

it measures the plain of the bed by caculating it probing the 4 corners when it prints the z compensates it

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

Looking at that picture your first layer is too low. You are jamming up the extruder with filament backing up because it cannot leave the tip.
Increase your first layer level or increase your z home by .1mm and try again.

floyed its ok to raise it but remember that you want it to stick its better getting 1st layer squished into the bed like it is on the right of the picture the other bit over extruding

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

the picture i just put a red circle around what my 1st layer looks like and never have any issues
picture

Edited 1 time(s). Last edit at 07/01/2014 02:28PM by chris33.

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Check my rubbish blog for my prusa i3

up and running
[3dimetech.blogspot.co.uk]

Oki had some progress ....
Did some Repetier setups a while ago when trying to improve print quality
Print settings
Advanced
Default extrusion widths
First layer
Set that both to 0.5
I changed now to default value 0
That got me 1st layer is NOT printing "thin" like before, it's printing like full layer just as for any layer above 1st layer
Not totally , but most print is not "thin" layer
So now 1st layer is printing almost normal ( still some alter thin/normal thicknesss) but most print is "not thin"
So it seems this change in Advance setting fix my problem ... as to why I don't really understand he he
Guess I just got punished for trying to be clever ... better let the default SW rule
Ha det gött
Bosse

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

Since there is still a little problem with not getting even (thin/thick) printout for first level I'll try out the auoto level concept see it that improve also
Could be that is another issue
Thanks guys for all feedback ... always helpful
Ha det gött
Bosse

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden

Quote
chris33
floyed its ok to raise it but remember that you want it to stick its better getting 1st layer squished into the bed like it is on the right of the picture the other bit over extruding

Agreed you want that first layer to stick but that is way too thin. What does it measure from the bed?
I find a first layer of .2mm-.3mm works great.

Did some organized testing on this with a 40x40 mm test object
The uneven thick/thin printout of layer 1 simply turned out to be misadjusted Z home.
Kinda what Floyd did indicate early on. My Z home was -0.4 mm
With layer height 0.3 that got my first layer print to start at physical Z -0.1

I added Z offset in steps of 0.1
Physical Z pos
-0.1 fail
0 fail but just very little area
1 ok whole 1st layer "thick"
2 ok - " -
3 partial bad adhension

So that was totally logic and a little bit lame I did not double check the Z home right away.
Still good learning for me and maybe for someone else reading this.

My first symptom though was the filament stopped going down even though feed wheel was feeding
Not sure now if that was due to the bad Z home or if it was a separate issue.
Since I got rid of it by real tight adjust of the feed pressure wheel

But maybe with hot end tight to the glass filament was just blocked from going down at all.
Have to go back testing readjusting tension for that feed pressure wheel I think.

So anyway thanks for all good comments. Real happy I found a non weird reason for the problem

Ha det gött
Bosse

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Prusa i3 Reworked, Delivered March 28 2014, RAMPS 1.4
Göteborg, Sweden