Weird printing result

Hi everyone!
I have a Pintrbot jr. and have printed a couple of things without problems. Now I am getting a bad result whenever i print. You can see it in the attached photo. It is like that materiel is not always extruded properly.
I thought it was the stepper skipping steps, but I tried to give it more current with the same result.
After that i tried tightening the the mechanism that keeps the filament at the hubbed bolt. Again - no change.
I then tried to set the steps pr. mm up to give it more material to work with. But I could se that it was too much, and it did not change the result.
I have tried different temperatures for the hot-end but nothing changes.

I have set the speed quite low to see if this was the proble, but again it doesn't matter...

I run it in cura.
Settings are:
1.75mm PLA
600 steps/mm extruded
200 degrees hot end
100% infill
0.2mm layers
1mm walls
print speed 30mm/s
travel speed 30mm/s
no support and no raft
Retraction 2mm and 0.5mm extra on start
retraction speed 25mm/s
infill overlap 15%
bridge speed 65%


Can anyone recognise this problem??

I am lost!

Regards Nic

I am having issues calibrating too, but not identical issues. Your temp seems too hot for PLA if that reading is true nozzle interior temp. temp indicated is dependant on extruder construction, so it is hard to know off hand if your temp is reading accurately to interior nozzle temp. I see mine start to ooze at 160C. I have been told that PLA will crystallize and cause problems at higher temps. You may want to check your PLA manufacturer's suggested temps. I use Natureworks 4043D PLA and The spec says its melt point is 135C, and will extrude at 160C and Ultimachine suggests starting off at 180C and other REPRAPers suggest it is best to extrude a little cooler to help it solidify quickly and prevent heat buildup.
I am trying reducing my extruder temp to 170C and added a fan to see if that helps me.

Of course the filament color can require higher temps to work the same, so take my advice with a grain of salt.
this temp calibration looks good, and has been recommended [reprap.org]

Hope it helps-

Edited 1 time(s). Last edit at 01/20/2013 11:07PM by rrr7.

It is quite difficult to spot the problem with that picture. I suggest you take a better one.

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Cheers,
Franklin Dattein

Definitely new pic required!

Yeah okay the picture is not so good, Try this one!

Regarding the temp. It is suggested on the filament to use around 195 C to print. I have printed succesfully with this material and other PLA materials before.

It seems like the problem occurs when printing "thin" walls, but it is hard to tell because on bigger parts the fault could be "hidden" inside the part.

Regards Nic

That's better! thanks ;-)

That looks like a problem I was originally having - I noticed my toothed belts were rubbing up against "bits" of the reprap...

Check all the way along your X and Y belts and make sure they're not rubbing... ANYWHERE - each time they would rub a tooth would get snagged on (in my case, a pulley I had on the idler) and it would cause a "twang" (or vibration if you want to be technical ;-P) and this would result in the same effect you're seeing here...

There CAN be other causes of course - but I would check this first up, in my limited experience - this looks like the same issue I was having which related to the toothed belt...

Best of luck ;-)

JazzyB

I think it looks a lot like extruder jamming. The filament starts slipping due to high resistance, and not enough plastic is deposited in that area.

• Clean out your nozzle
• Try raising the temperature
• Lower your printing speed
• See if you can improve the grip on the filament in some way

Edit: I see you have tried some different temps, but which ones? I use cheap chinese pla with a cheap chinese printer basically, and I usually print at 220-235 degrees C if I need to print at any speed above 35 mm/s. Try it.

Edited 1 time(s). Last edit at 01/21/2013 05:27AM by Speedsoda.

Hi thanks for the replies.
I have made sure that the belts move freely and nothing is vibrating.
I have just tried a print at 15mm/s (SLOOOOW) with the same result...
I have tried to raise the temp and lower it, nothing changes.
The nozzle is cleaned.
The grip of the filament is good and i have tightened it some more to make sure it doesn't slip.

I have tried to print some more solid pieces and that gives a very nice print result.
It is only when i print walls of 1 or 2mm in thickness there seems to be a problem...
The problem is that i really need to print such items.....

Regards Nic

What firmware are you running?
If your firmware accepts this (as I said, I have limited experience, I am not sure which ones do and don't - but I know Marlin accepts this) you can try issuing a M221 S### (On-the-fly flow rate change) where S### is the flow rate change in % (So S100 = 100%, S125 = 125% and so on)

This allows you to change the flow, your e-steps are a lot lower than mine (924) but that could be due to the design of your machine... Still, if you try this M221 S125 or even 150, you might find that the issue is not enough plastic, meaning it leaves a blob-trail-blob-trail sort of effect.

If the M221 command is not accepted you will have to either use M92 E### to set the esteps on the fly (in my experience this also screws the extruder around - forcing out a lot of plastic in a blob when you make big adjustments) or flash firmware to change the e-steps.

ALSO

When you say 1mm walls, are you saying your print settings are .2 layer height and 1mm layer width? what size is your nozzle? I usually use .25 height x .5 width for a .5 nozzle - I'm not 100% on this but I think that ratio you are using is fairly high!

Hi.
I don't now what firmware the printrbot jr. is running, but it is the standard on the printrboard i use.
I have tried to increase the e-steps but this just gives me a bad printing result with to much plastic. I have calibrated the extruder to this amount and it works fine when printing bigger things.
And i guess it makes no difference if i change the amount before the print like i already have, or on the fly?

When i say 1mm walls, i mean that my print has 1mm thick walls. Also the setting in cura is 0.2mm layer height and wall thickness of 1mm. I run with a 0.5mm nozzle, so it would not change if i choose to set it to 0.5mm walls when printing an object that is 1mm in width as far as i can see...

Regards

nic6911 Wrote:
-------------------------------------------------------
> Hi.
> I don't now what firmware the printrbot jr. is
> running, but it is the standard on the printrboard
> i use.
> I have tried to increase the e-steps but this just
> gives me a bad printing result with to much
> plastic. I have calibrated the extruder to this
> amount and it works fine when printing bigger
> things.
> And i guess it makes no difference if i change the
> amount before the print like i already have, or on
> the fly?
>
> When i say 1mm walls, i mean that my print has 1mm
> thick walls. Also the setting in cura is 0.2mm
> layer height and wall thickness of 1mm. I run with
> a 0.5mm nozzle, so it would not change if i choose
> to set it to 0.5mm walls when printing an object
> that is 1mm in width as far as i can see...
>
> Regards

Have you tried looking through your gcode? It's a PITA but you may find something strange there. Or use something to view the Gcode and make sure the issue isn't there.

typically as others have said the broken lines when printing is because you are not extruding enough filament temporarily, the extrusion gets thin and snaps repeatedly and you get what's in the pictures.
I see it with PLA occasionally when the temperature is borderline, but what's actually happening is that I get enough back pressure than the filament slips temporarily in the extruder, raising the temperature 5 or 10 degrees will usually resolves it in my case.
You can also get it if you have an issue with retraction, I'd look at the GCode or watch the print, and see if the breaks are occurring when a new perimeter starts, that's usually an indication it's a retraction issue. The easy way to confirm is to run the print with retraction turned off, you'll get other issues, but if the breaks go away, you at least know what the culprit is and can work on fixing it.

Hmm.. I have tried to turn off retraction, turn up the heat and I have even built a new printer that does exactly the same thing on some prints.
I know it's because it doesn't extrude enough filament temporarily, but i don't see why... If I adjust E-step I will get to much extrusion in general and a bad result...

I have used different types/makes of filament, but all are PLA.

Here is my gcode and a picture of a model that doesn't print correct on both of my printers.

• I have tried with and without retract.
• Increasing temp to about 210 degrees doesn't help
• My homemade printer has a j-head hot end
• My Printrbot Jr. has the standard fitted hot end
• I print PLA 1.75mm
• I have tried running at speeds from 15-70mm/s
• I have tried to increase and decrease E-step
• On the print for the picture I calibrated E-step again and printed on my homemade printer

... the horizontal 'waves' in your print are most likely caused by faster extruding filament than moving the head ... so the filament is laid down in 'serpentines' ...

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Viktor
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