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# Top Layers not touching - UM2

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Posted · Top Layers not touching - UM2

Looking at the gcode the Nicolinux provided... it's exactly correct. the infill lines on the top are spaced 0.57mm apart along the edges of the square, which is the correct distance to give a perpendicular separation of 0.4mm, given that the lines are angled at 45º to the edges.

The extrusion amount for each line is exactly correct for a 0.2mm layer height, and 0.4mm extrusion width.

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Posted · Top Layers not touching - UM2

I also made some calculations out of the code...

If I assume that the filament diameter is 3 mm, then I get 0.799 mm2 for the sectional area of the extrusion. Great!

However, if the filament is 2.85 mm, then I get only 0.721 mm2, which is 10% less, and looks like under extrusion

For the outer wall, the area is 0,765 mm2, assuming 2.85 mm diameter, so considerably less under extrusion, hence almost not visible.

So, which is actually the diameter of the filament in use?

LE > there is a 0.1 factor that I don't get. The area of a 0.4 mm by 0.2 mm extrusion in 0.08 mm2. I assumed all G parameters are in mm, aren't they?

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Posted · Top Layers not touching - UM2

I will post the code after work tonight and take a few pictures. The quality of the pictures wont be great as it is hard for me to take good pictures with my non working hands but Ill give it a shot.

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Posted · Top Layers not touching - UM2

I also made some calculations out of the code...

If I assume that the filament diameter is 3 mm, then I get 0.799 mm2 for the sectional area of the extrusion. Great!

However, if the filament is 2.85 mm, then I get only 0.721 mm2, which is 10% less, and looks like under extrusion

For the outer wall, the area is 0,765 mm2, assuming 2.85 mm diameter, so considerably less under extrusion, hence almost not visible.

So, which is actually the diameter of the filament in use?

LE > there is a 0.1 factor that I don't get. The area of a 0.4 mm by 0.2 mm extrusion in 0.08 mm2. I assumed all G parameters are in mm, aren't they?

Ultigcode expresses the E coordinates in cubic mm; the printer firmware takes care of converting them into linear mm of filament to feed in, based on whatever filament size you specify in the machine.

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Posted · Top Layers not touching - UM2

Ultigcode expresses the E coordinates in cubic mm; the printer firmware takes care of converting them into linear mm of filament to feed in, based on whatever filament size you specify in the machine.

Aha! Wow, but this means the firmware should be aware of the filament diameter, which is basically a characteristic of the machine, but does not yet have the required constancy over the entire range of manufacturers.

Anyway, then indeed the extrusion is correct in code.

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Posted · Top Layers not touching - UM2

OMG!

Don't tell me this is a sofware fail. Renthal, could you please share the .gcode file? I'd like to print it NOW

Did you get a chance to print my test cube? I'm curious about your results being you liked my post but no reply yet.

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Posted · Top Layers not touching - UM2

Hi Renthal,

I did print it but sadly I used a filament color where it was hard to see if the problem still persists. I have now a longer job running, but I'll try it again after it is finished.

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• 1 month later...
Posted · Top Layers not touching - UM2

Hi Guys.

That's definitely problem with Cura.

Why the wall lines can touch each other no matter what direction they go but infill lines won't ??

Cura is creating too wide gaps between infill lines and even properly squished lines won't cover those gaps unless you over extrude a lot.

I print mostly with 0.2mm layer hight

I've this issue since I received my UM2

I can achieve all speeds without under extrusion issue, Ultimaker black PLA, 230C, filament diameter set to 2.85

With the same settings two infill lines are about 1.5mm wide (from edge to edge), each line is around 0.55-0.60mm wide, gap between lines is around 0.3-0.4mm (hard to measure to be honest)

It looks like Cura is skipping every second line of infill, you can clearly tell by looking at flat closed surfaces. In my opinion is doing 0.4mm line, then 0.4mm empty space and then another 0.4mm line.

For me only workaround to make those gaps less visible was to set nozzle size to 0.3mm (even if real size is 0.4) or to over extrude by setting filament diameter to 2.65mm instead of 2.85mm which I'am doing right now.

Ultimaker black PLA

Nozzle temp 230

Filament diameter set to 2.65mm

Nozzle size set to 0.4mm (as it should be)

Print speed 40mm/s

0.8mm shell

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Posted · Top Layers not touching - UM2

Can you reproduce this problem with PLA from another supplier?

The reason why I ask is because yesterday I printed with a roll Ultimaker - Ultimate Blue and I had the same problem. But when I print with ColorFabb & Faberdashery I don't have this issue.

As I wanted the Ultimate Blue color I decided to slow down the print from 50mm/s to 30mm/s and increase Expert -> Infill overlap from 15% to 25% and it came out almost perfect.

So I'm not convinced that this is a completely Cura issue, it seems to be material dependent.

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Posted · Top Layers not touching - UM2

I've been suffering from the same problem. I posted in another thread but should have seen this instead. My tests and description is found here: http://umforum.ultimaker.com/index.php?/topic/7401-top-layer-the-distance-between-the-lines-of-plastic/?p=70736

We've seen the same thing with PLA/PHA from colorfabb and with XT as well.

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Posted · Top Layers not touching - UM2

Yes, same issue no matter what filament we use.

Within last month we've tested almost 40 different colours, mostly Colorfabb and Ultimaker, PLA, PLA/PHA, XT, Woodfill Fine and Glowfill.

Some of them flow better than others so problem is more or less visible but still exists.

The best results so far we have had with glowfill and woodfill.

I'm going to test Cura for Windows instead of Mac version just to see if there is any difference.

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Posted · Top Layers not touching - UM2

I just printed Renthals test cube and it looked very nice up until the 4th layer where the lines started spreading again. This also coincided with when the fans started to come on a bit more ...

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Posted · Top Layers not touching - UM2

And here's the picture:

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Posted · Top Layers not touching - UM2

Looks like underextrusion to me. Approx 20-40%. How many layers was the top? Do they get better each time? I'm thinking the top is sagging a bit. It takes a few layers to recover. Maybe 4 to 6 layers. I recommend printing one of these cylinders to test your extrusion:

http://umforum.ultimaker.com/index.php?/topic/4586-can-your-um2-printer-achieve-10mm3s-test-it-here/

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Posted · Top Layers not touching - UM2

This is not underextrusion, not I'm my case anyway.

6, 7 layers for top and bottom, even 100% fill doesn't work, you can always see layers from below between those gaps.

Gr5 could you print simple box yourself and show us your result please.

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Posted · Top Layers not touching - UM2

Well, I've run the test cylinders and get 10 mm^3/s without any problem from 230C and up. At 220 C I get up to 7 mm^3. So I would assume that there is something else at play here?

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Posted · Top Layers not touching - UM2

I've updated UM2 firmware and Cura to 14.09, no difference.

Also tried slicing with Cura on Windows instead of Mac, the same result.

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Posted · Top Layers not touching - UM2

Gr5 could you print simple box yourself and show us your result please.

Second and 3rd photographs here show example of boxes with varying underextrusion. 4th picture shows no underextrusion:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/

These simple objects were sliced with cura 14.07 a few days ago:

I have had very little trouble filling in the tops of boxes. Unless I was underextruding for some reason.

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Posted · Top Layers not touching - UM2

My problem with the under-extrusion theory is that I can't seem to fill in the top surfaces (or surfaces anywhere in the print) running at 1.6 mm^3/s while I'm able to produce nice extrusion test cylinders at 10 mm^3/2. Would this indicate that there is some other settings then that is causing my under-extrusion problems that is not active when running the extrusion tests?

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Posted · Top Layers not touching - UM2

Something is strange. It could be:

- flow is not set to 100% (check tune menu while printing) on UM2

- diameter of filament doesn't match diameter set on UM2 (e.g. you set 3mm but filament is 2.85mm)

- You didn't use ulticode mode in Cura and set the flow or filament diameter wrong in Cura

- No infill to support top and not enough layers (with no infill you need maybe 1.0mm top/bottom thickness)

- 20% infill selected but not enough top layers (with 20% infill you need maybe .6mm top/bottom thickness)

- infill set to 80% but "solid infill top" or "spiralize" or "only follow mesh" unchecked in Cura expert settings

- infill speed higher than print speed (should be 0 - advanced settings)

- underextrusion (try printing at 240C, .2mm layer, and at 20mm/sec - even a half clogged nozzle should be able to handle this)

- top/bottom thickness is not an integral multiple of layer height (e.g. top layer thickness is 1mm and layer height is .21mm)

- Z stage is moving too far on each move causing mild underextrusion (nozzle too high off part for last layer)

- Z stage steps/mm miscalibrated

- Extruder steps/mm miscalibrated

That's all I can think of right now.

If you send me gcode for 20mm cube (keep it small! - preferably only 10mm tall try to make it under 20 minute print) and post photo of your problems I will print it on my UM2. Post gcode on some web service somewhere and provide a link.

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Posted · Top Layers not touching - UM2

Hi again.

Thanks for all the help. My spontaneous answers that I can give without going back to work is:

- flow is set at 100% (even tried 105% without any change)

- Diameter of filament matches filament (checked with caliper)

- Ulticode is used

- 20% infill and 0.6 mm - 1 mm top and bottom used with 0.1 mm and 0.2 mm layers

I'll check your other suggestions and get back.

Thanks again!

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Posted · Top Layers not touching - UM2

Here you go, box 30x30x5

http://speedy.sh/D7bSu/test-box.gcode

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Posted · Top Layers not touching - UM2

Hi again.

I managed to check my other Cura settings as well:

- Solid infill top and bottom checked

- Spiralize and only follow mesh unchecked

- infill speed 0

I can try the high temperature printing tomorrow morning and see what happens.

If there is a problem with Z-stage or extruder calibration, how is this best tested?

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Posted · Top Layers not touching - UM2

Worked great for me - no holes - 220C:

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