underextrusion

[warmbloed 0]

Hello everyone,

I recently started getting some under extrusion issues in my prints, I have had issues with prints not holding water before, however I have never had an issue this big before.

The nozzle has been cleaned recently, using the 'atomic' method, but also by heating the heaterblock and nozzle assembly and blowing compressed air through backwards.

Some photo's:

https://www.dropbox.com/s/mu41ogai6q63t84/IMG_1730.JPG?dl=0

https://www.dropbox.com/s/bcu33zgt0wjys3x/IMG_1731.JPG?dl=0

STL files are treads by LoialOtter on thingiverse:

http://www.thingiverse.com/thing:35668/

printed using the default 'fast'settings in Cura for the Ultimaker original.

I hope I have provided enough information, if not I'd be happy to provide more as needed.

Kindly,

Warmbloed

 

[3dnerd 5]

Hi,

I am also still a newbee so I don't know if it helps. But I had similar issue.

I guess your are printing with white PLA? What I did is I changed the nozzle temperature from standard 210 degree to 220. Then the filament gets more liquid and the single paths could melt much better together.

I don't know how it is done on UM1 since I have an UM2 but I think you will know...

 

[warmbloed 0]

Hello 3Dnerd,

I am indeed using white PLA, the roll is about 5-6 months old, and was stored in an airtight container with a moisture eater. I would raise the temperature, but the strange thing is that the bottom layers are absolutely fine but it is only the top that appears to have this issue, almost as if something has changed halfway through the print. I will retry tomorrow with a higher temp.

as far as I can tell there is no major difference in technology or mechanics between the UM1 and 2, but I may be wrong on this as I have only seen the UM2 in videos so far.

 

[gr5 964]

printed using the default 'fast'settings in Cura for the Ultimaker original.

 

Don't use those settings. Tell me fast settings doesn't help as this has a different meaning for different versions and I'm not going to take the time to install your particular version of cura and then see what speed it is when you can do it yourself. Better to use the "full settings" mode.

The reason the layers look better on the bottom is probably that it was printing slower - by default in Cura it prints the bottom layer at a slower speed and then changes gradually over the next 2 or 3 layers to the desired printing speed.

What you are seeing on your prints is underextrusion. Both in the seperation in shell outer passes and also in the gaps between infill (sometimes those gaps are caused because there isn't much support and it takes a few layers but the shell gaps are definitely underextrusion).

The most common cause of underextrusion is printing too cold or too fast. For PLA at .2mm layers you should print no faster than:

20mm/sec at 200C

30mm/sec at 210C

40mm/sec at 225C

50mm/sec at 240C

These values are right off the graph here which is for UM2 but the top speeds are about the same for the two printers. The values I mention above are half of what the printer is capable of - so those are the top speeds I prefer to print at.

Of course with .1mm layer you can print at double those speeds.

The problem is the viscosity of plastic gets very thick (think toothpaste) at 200C versus more like honey at 240C.

I don't recommend going over 240C unless you are printing at higher speeds then mentioned here as 250C is both bad for your print head on UMO and also bad for your nozzle as PLA can caramelize into a nozzle clogging gunk if you leave it for even just a few minutes at 250C. So again, even though you can definitely do it, I recommend 240C for the top PLA temperature.

http://umforum.ultimaker.com/index.php?/topic/4127-um2-extrusion-rates-revisited/

Also note that different brands of PLA and especially different colors have different viscosity so your PLA may vary a bit from these values.

 

[3dnerd 5]

Hi gr5,

to correct the underextrusion is it also possible to increase the 'flow rate'?

Or what is the 'flow rate' setting for? (I am on UM2)

 

 

[DidierKlein 648]

Adjusting the flow rate will overextrude so it could resolve underextrusion but it's not the way to go.

It's better to adjust the temperature and the speed to avoid under-extruding. If this doesn't work then there might be something else responsible.

You can check http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#underextrusion for more information

 

[3dnerd 5]

Hi Didier Klein,

thanks, that helped...