Newbie Print Quality Help Please

My Prusa Mendel 2 is up and running, but the print quality is very poor. I've tried adjusting the various settings, leveled the bed, added cooling, but I need some help identifying the problem to fix it. Please see the attached photos. Can anyone tell me what could cause this and how to adjust to correct it? At this point I don't even know what to search for.

I'm printing PLA at 210 C, the bed is at 60 C. Extruder is a J-head MK V. The temps remain steady during the print. Pronterface with Slic3r. The skirt and perimeter appear perfect and stick fine, but the infill fails to extrude or attach in many cases. Most of the next several layers look clumpy (is that a word?) like a bad bird's nest. Later in the print things settle down a bit, but the quality is still poor.

Any advice is appreciated, but please don't just say "check your calibration" as that is too general and I've done it many times.
Thanks!!

Edited 1 time(s). Last edit at 05/24/2013 06:01PM by poppen.

Hi
As i and a few others have recommended before to people, when you start printing its best ( certainly when you have issues ) to use the standard pints models
that many of us use to set up our machines
thin wall 0.5
20mm box
It makes it much easier for people to compare and comment when your using models we know.

From your pics it looks like your way too hot . Start with the standard 185 degrees for PLA and use 30mm/s print speed.
Try those setting on the 20mm box model above and post a pic
the "failed 4" pic looks like you dont have enough material coming out in places / but in other places it looks better . Maybe your extruder is slipping ?
Of course the best start is to check and double check your e steps

Good luck

Edited 1 time(s). Last edit at 05/25/2013 07:50AM by bigfilsing.

bigfilsing- Thank you VERY much for your suggestions. It seems you were right on target! I lowered the temp down to 185 C and raised the bed to 65 C. The thermistor for the bed is under the bed heater plate so the glass on top was not at the temp the thermistor was showing. It just needed a bit more.

Just as important, there was plastic that had collected in the grooves of the hobbed bolt (probably from overheating the PLA). I cleaned that out and instantly saw tremendous improvement.

A new photo of the 20 mm cube is attached. It's the first thing I printed after making these changes. I reprinted the box top successfully too (was "failed 2" above). The results speak for themselves.

Thanks again!!!

You're welcome.

The heat from the hot end shouldn't effect you're hobbed bolt and cause it to clog up. So i would say you have the compression springs too loose ( allowing it to easily slip and chew the filament) or way too tight crushing the filament.

From the pic ( 20mm cube) it looks like your Z steps need calibrating but that might just be the camera angle. Measure it and compare to the stl model. Assuming you used the model link i posted earlier it should be 10mm high ! Yours looks at least as tall as it is wide / deep (20mm)
( a quick guess would be that your Z steps are for 16 micro steps but your board is only doing 8. Hence it being twice as high as it should be or there's some scaling going on in your slicer software)

Once you have the Z steps correct try and print the 0.5 thin wall . I find it very useful for experimenting with temps and surface finish. Try raising or lowering the temp a couple of degrees to see the net effect. Everybody uses different temp settings due to their set up and different types/ colours of filament. No 2 heating elements perform the same either so its worth experimenting with.

The 20mm cube pic you post still looks like there's a bit too much material being extruded but its difficult to say until you have the Z axis correct.
Really spend some time experimenting and getting your steps per mm on all axes spot on. Once done you wont have to mess with them again.

Good luck

Thanks, I'll do as you suggest to be sure that the steps are correct, but I didn't use the cube you suggested. The one I printed is actually 20mm square. The sides measure ~19.45mm to 20.30mm.

Other than a bad photo, what suggests to you that too much material is being extruded?

Even if its a 20mm "high" box it still looks too high

Looking at the front right hand corner you get some ooze at the end of a layer , the corners look slightly over extruded and the genral surface finish suggest to much material where some layers wont fit on the previous so "stick out"

Main thing is get your Z steps sorted out first. Pretty pointless trying to diagnose other issues if the steps per mm aren't correct

Print the 0.5 mm thin wall and post a pick

Edited 2 time(s). Last edit at 05/26/2013 11:25AM by bigfilsing.

I'm not sure what you mean by "Even if its a 20mm "high" box it still looks too high". It's supposed to be 20 mm and it measures out at 20.25 mm.
In any case, I printed the .5 thin wall as suggested. I welcome your comments and suggestions.

All i meant was in the photo the cube looked taller than 20mm..must have been the camera angle.

The new results look pretty good to me . Im a bit intrigued by the top surface of the 20mm cube . it looks like theres a gap between top fill and the perimeter. Not sure whats going on there im afraid

If youre going to print objects like the fan cooling duct ( failed 1 pic in your first post) then you'll need to slow the print speed down to allow each layer to cool before the next layer comes along and or use a fan

Good luck

Oh, yes it's the camera angle. I'm pretty happy with the new results too. It's amazing how small adjustments can make big improvements in quality.

I have noticed the gap in the top of the cube too. The settings in Slic3r call for the top and bottom three layers to be solid, but only the first one ever is. I suspect there's another setting somewhere that I'm missing. Perhaps someone else has an idea?

Poppen,
may I ask what size nozzle you are using.
also what is the measured thickness of the walls of the .5 thin wall print,
it looks to me as though there is some fill on the top layer in your photo, I think the print should be only 1 extrusion width wide.
With the 20 mm box the gaps between perimeters is like laminating and could have something to do with layer width settings.
Hope this is helpful

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My nozzle is .35. One side of the thin wall is .85 and the others are .95. My layer height setting is .27. I'm using 3 mm filament (2.9).

From my experience with different size nozzles, the walls of the 0.5 mm thin wall object should be
about the same width as the nozzle, so with your 0.35 mm nozzle your walls should definitely
not be .8 or .9
What are your settings in slic3r for, advanced under print settings and perimeters under print settings.
Are you sure your nozzle is .35, I only ask as I bought a .35 nozzle and it turned out to be .4

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I have no way to measure the nozzle, so I must assume (I know, I know) that the supplier sent me what I bought. How did you measure yours?

The advanced settings are:
Default extrusion width - 0 (auto)
First layer - 200%
Perimeters - 0 (default)
Infill - 0 (default)
Support material- 0 (default)
Bridge flow ratio - 1
Threads - 2

I used fine drill bits to measure mine, not very scientific I know, but a .4 passed through and a .45 did not!,
so it was definitely not .35.
Under print settings, layers and perimeters , what are your settings.

Edit: maybe a silly question, but you did use the .5 thin wall.stl found on this [reprap.org] page didn't you

Edited 1 time(s). Last edit at 05/28/2013 05:11PM by Myles.

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Myles Wrote:
-------------------------------------------------------
>
> Under print settings, layers and perimeters , what
> are your settings.

Layer Height .27
First Layer 100%
Perimeters 3
Horizontal Shells - Solids layers Top 3 Bottom 3


> Edit: maybe a silly question, but you did use the
> .5 thin wall.stl found on this
> [reprap.org] page didn't you

Yes!

You might try perimeters =1
I have been racking my brain over the .8 mm walls on your thin wall print
and I'm sorry to say that it has me stumped.
It should only be laying down 1 line of filament on each layer
and about the same width as your nozzle, why it is building 2 walls with a fill in between I have no idea,
I shall keep thinking about it though!
Lets hope someone more knowledgeable will spot the problem and help
Sorry I could not have been of more help.
I will be interested to know what the solution is.
All the best of luck

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i have sliced the thin wall with the settings you have given
and i attach it for you to try
hope it works

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