A Tale of Two Printers

[taikonaught 2]

Hello there,

I just bought myself an Ultimaker 2, but when it arrived, the box was damaged and the printer itself was dented and battered. I told the reseller about the damage and they said that they would replace it with a new one. I did a couple of prints on the damaged machine before I sent it back, and it seemed to work perfectly, and I was very impressed.

When the new machine arrived, I printed exactly the same model, using the same g code, but get a very different result.

The photo shows the first print on the left and the second on the right. Any idea what the cause is?

The conditions were all the same, settings the same, the only difference was the actual physical printer...

Is there an easy fix, or should I be asking for the damaged printer back?!

Thanks in advance.

[francfalco 37]

Looks like retraction isn't happening on the second print?

[taikonaught 2]

Looks like retraction isn't happening on the second print?

 

Retraction was on- set to 4.5mm in both cases.

[Dim3nsioneer 557]

Temperature measurement might differ a few degrees from one printer to the other. Try decreasing the temperature by 5 degrees and see if this improves the quality.

[SandervG 1,521]

Do you have a better picture that shows what went wrong?

It would help isolating the problem.

For starters I would also play around with the temp a little bit.

What settings did you use for printing this?

[taikonaught 2]

The settings I used for to print these were:

0.05mm layer height

Initial layer thickness 0.3

shell thickness 0.5

wall count 2

Bed temperature 50

Retraction 5mm

combing on

print speed 40

travel 150

infill Grid, 1mm spacing

enable cooling at 1mm

No support.

Dropping the temperature seemed to help a little, but the problem persists. Any other ideas? Should I keep dropping it below 200?

[SandervG 1,521]

Depending on your printspeed, 200ºC could work, even down to 190ºC if your speed is low enough.

But I could also see some other tweaks in your profile.

For starters, to rule out any inconsistencies in your hardware, could you do a print with default setting in Cura?

Second, I would suggest these settings:

0.06mm layer height

Initial layer thickness 0.3

shell thickness 0.8

wall count 2

Bed temperature 60

Retraction default

combing on

print speed 50

travel 150

infill Grid, 1mm spacing

enable cooling at 1mm

No support.

Looking forward to see the results!

[taikonaught 2]

Hi Sander,

I updated the firmware to the latest version, then printed the same part again with your recommended settings. Then again with the same settings, but dropping it to 190degrees, yet the problem remains...

[SandervG 1,521]

Hi, could you upload some detailed pictures of your print, and especially where it fails?

Currently I am in Boston for a show, so my response may be a little bit slower then usual, my apologies!

What happens when you increase temp to 220ºC/225ºC?

[taikonaught 2]

The print quality is generally ok, its just that the new printer deposits a large amount of unwanted material on the outside of the printed object.

I am trying to determine whether it is a hardware issue that I should raise with the people I bought it from.

[francfalco 37]

Intriguing problem you're having...

It so much looks like retraction isn't happening, but as you say it is set up for standard retraction and the printer is actually retracting.

Just out of interest - have you printed with retraction turned off?

Any chance i could to get the .stl file to test on my UM2?

Let me know please

cheers

Edited August 3, 2015 by Guest

[xeno 108]

Did you take pictures of the first damaged printer,

compare those to the new one, maybe a different nozzle, or something.

it's just weird

or just kick some sense into the printer

[bartkonings 0]

The color difference in the last picture looks like a deviation in either temperature or filament, the problem might even be caused by the filament. I’m interested in the gcode, I could try it out on some of the printers here and look at the differences.

[LePaul 321]

or just kick some sense into the printer

 

I was thinking the same thing...maybe a kick/dent like the other printer might help

Just a shot in the dark, wondering about a partially plugged nozzle. Maybe an atomic pull (

) ?

What filament are you using?

[taikonaught 2]

Did you take pictures of the first damaged printer...

 

I did take some photos of the first printer, but not of the extruder... An I have seriously considered trying to beat some sense into the new machine.

[taikonaught 2]

The color difference in the last picture looks like a deviation in either temperature or filament, the problem might even be caused by the filament. I’m interested in the gcode, I could try it out on some of the printers here and look at the differences.

 

The first prints were a light fleshy pink colour, when using white. I thought that the test prints Ultimaker did in the factory may have been in red, which stained the white, but maybe not.

The two models were made from the same roll of UM White PLA that came with the machine...

Edited August 8, 2015 by Guest

[francfalco 37]

Just test printed taikonaught's Bumper car .stl file (chopped the bottom off to save print time).

Front car is standard Cura 15.04 'quick print' PLA settings - looks fine

Rear car has retraction turned off - similar issue

It's got to be a retraction problem - no. What else could it be?

But if retraction is 'on' and working and different temp tests have been done - what could it be if not a retraction issue?

[Dim3nsioneer 557]

But if retraction is 'on' and working and different temp tests have been done - what could it be if not a retraction issue?

 

Completely different retraction settings? (just a shot in the dark)

[francfalco 37]

Completely different retraction settings? (just a shot in the dark)

Agreed that would make sense, but apparently retracting settings have been the same for all tests (mine included) - the default: 4.5mm @ 25mm/s.

Edited August 9, 2015 by Guest

[Dim3nsioneer 557]

25mm/s is slow. I use 40mm/s iirc. It certainly improves quality in terms of less stringing when increased.

And I use a travel speed of 250mm/s which an UM2 is absolutely capable of.

Edited August 9, 2015 by Guest

[taikonaught 2]

Hmmm, it certainly looks as if it is a retraction issue, and the point was made very clearly by Franc's test prints (thanks for doing that, Franc), but I can see the filament retracting in the tube, so I know it is working... Speeding up the travel may help, and I will try that tonight.

I tried all of the above suggestions and got some nice, clean prints of some flat, low profile pieces. I thought maybe the problem was fixed, so I printed my little bumper car test piece and got the same annoying deposits... Grrr!

Last night I put a spirit level across the top of the machine and found that it is not sitting dead level. It is only out by a tiny bit, but that could be the reason, no?

The first print I did on the first machine, the printer was sitting on the floor, which is very stable and very flat. I am hoping that leveling it fully is going to make all of my problems melt away.

[foehnsturm 969]

Another shot in the dark:

The shaft of the extruder stepper is flattened I think. If the set screw is just a little loose it will still feed as the screw catches where the flat part ends. But there will be some backlash before reverse movement starts because the screw has to catch on the opposite end.

[SandervG 1,521]

Hi @taikonaught, how is it going? Did you manage to sort it out?

[taikonaught 2]

Hi @taikonaught, how is it going? Did you manage to sort it out?

 

Hi Sander,

despite many suggestions from many helpful people, the problem persists.

It is also very noisy. When the main fan comes on, there is a loud, unpleasant sound coming from somewhere in the head. I have tightened every screw I can see, but it doesn't help...

Woe is me. I wish I had the first one back, as this one seems like a dud.

[SandervG 1,521]

Did @Foehnsturm 's suggestion make any difference?

I am also inclined to think it has to do with retraction.

For a minute I thought it could also be that your bowden could not be fully inserted (like a very small gab) between the bowden tube and PTFE Teflon part, but that would probably result in under extrusion, not stringing.

It could be that your temp sensor is off by a few degrees, but based on your earlier pictures by upping or lowering the temp you don't really clear the stringing, you are getting closer to under extrusion.

What I understand is that the gcode is set for retraction, but it looks like it isn't doing it.

So, if the feeder doesn't grip the filament with sudden movement, a loose set screw could make sense.

It is shown on this image:

By opening the feeder you can get access to this sleeve.

Note that by removing the feeder case, your motor will probably fall in the inside of your Ultimaker. By simply removing that cover (1 screw is on the bottom) you can mount it back when finished.

Let us know how it goes!

.. it could also be that your tension in the feeder is just way off. Have you experimented with that white lever on the side? (there is a set screw - hole on top of the feeder to change tension).