Hey Sigi, thanks. Checked that too. But most of my filament seems to have an average diameter of 2.9mm. Usually I unroll the spool a bit, then measure the diameter in different places. I always measure only one side of the filament (not the one that is bent, because this would mess up the measurement).
Okay - new theory: Your nozzle diameter is smaller than mine.
I just measured it with a camera as you can see. I used photoshop which measures sub pixels nicely at any angle. I measured 10mm for calibration and then measured the nozzle diameter vertically, horizontally, and both diagonals and averaged the 4 measurements. If I measure to the edge of the light blue I get: 0.43mm
If I measure to where it looks like the metal starts I get 0.49mm.
I started with a cold nozzle with a little filament hanging down and broke off the filament flush with my fingernail.
Okay - new theory: Your nozzle diameter is smaller than mine.
Hmm, an interesting suggestion; I download this image Nicolinux posted eairler in this theread:
blew it up really large and tried to measure the inner tip by assuming the larger opening was exactly 3mm. If this is a correct assumption, I get something like the nozzle diameter is around 0.35mm; although without some exact measurements my assumptions leave me dead in the water, and I would be surprised to see this much variability in the nozzle tip size; if it's smaller than yours I don't think the difference is as large as my measurements suggest.
Hi guys,
gr5: Interesting idea indeed. I tried to take some closeups of the nozzle but the iPhone 5 camera faild badly.
I'll clear the nozzle and will measure the tip with a digital caliper.
@Aaron: You are right, 0.35 would be a huge deviation at this scale.
Nope, my digital caliper is too blunt to measure the tip. I'll have to come up with something else. Maybe I can find a wire with an ideal diameter, measure it and see if I can carefully insert it into the nozzle.
but the iPhone 5 camera faild badly.
I disagree! that photo is better than mine.
Please:
1) Turn UM2 off, put it on it's "back".
2) Slide nozzle to the top (the front).
3) Tape a caliper to the print head so it is as close as possible to the nozzle.
4) Photograph the same thing but with both ruler and nozzle in the same photo.
Thanks but the iPhone 5 cam is really bad for such a job. I can't get it to focus on the nozzle.
I'll try again later today. Maybe I'll get lucky.
Such small holes will be hard to measure with common instruments, most easy would be with a precision small drills.
Would it be possible to pull the filament from other end of bowden (going to the hot end) and measure what force is needed for it?
Since this under extrusion problem is quite widespread, is there any answer from Ultimaker themselves?
@hacklordsniper: You'd need to measure the force needed to extrude something and I don't know how one could measure it accurately.
I am not aware of an official answer, only some scattered threads about it.
By the way, just to rule out another source for this problem, I bought a cheap sd card and printed the extrusion test from it. Made no difference.
I meant it would be interesting to measure force that is needed to bring the filament until the hot end. This could show problems in extruder setup
I searched also for any official answer, i guess they don't care as long the sales are going. Or implementing a solution now could result in all past buyers asking for the upgrade
I meant it would be interesting to measure force that is needed to bring the filament until the hot end. This could show problems in extruder setup
But this would only detect problems inside the bowden tube. The extruder pulling force test did prove that it is strong enough.
I searched also for any official answer, i guess they don't care as long the sales are going. Or implementing a solution now could result in all past buyers asking for the upgrade
Nah, Ultimaker is not like this. These are the pains of a successful product launch and maybe quick growth of the company.
i guess they don't care as long the sales are going. Or implementing a solution now could result in all past buyers asking for the upgrade
Absolutely not. You are confusing UM with Makerbot.
They are just a very small company and are very busy. This is something they are looking into seriously. Part of the problem is that it's not clear what the problem is or if there is a problem. I know they are redesigning the extruder but in the end they might decide the current design is better (I doubt it).
UM is the kind of company that would offer free extruder upgrades to all owners of the UM2 even though they have no legal obligation to do so. But only if they find there is a serious problem with it. It may be the solution has nothing to do with the extruder. I have 5 good theories for what Nicolinux's problem is.
Also it's not clear if 1% of the people out there have extrusion problems or 60%.
Okay I just looked at your picture, nico and calibrated it using both the nozzle outer diameter of 6mm and opening of 8mm. I get that your nozzle hole is smaller than mine by 30% to 60% area.
Doing identical comparison, metal to metal, I get that my hole diameter is .49mm and yours .38mm (that's where the edge curves inward into the hole).
Comparing the blue filament in my hole - blue edge to edge - comparing that to your nozzle hold metal to metal I get that my hole diameter is .43mm. Either way my nozzle hole seems larger than yours by a significant amount (at least 30%).
This technique of course could use some accuracy improvement! It's hard to say exactly where the edge of the hole is. I tried the same technique for both photos, but differences in lighting can change where it looks like the edge is. That photo that showed light coming through the nozzle hole would be the most accurate if one could photograph a ruler at the exact same distance (preferably in the same photo!).
I measured 4 different directions (horizontal, vertical and 2 diagonals). If I use the SMALLEST of my 4 "metal to metal" measurements of my nozzle hole, and the LARGEST of the 4 "metal to metal" openings of your nozzle hole I still get .46mm for my nozzle versus .40mm for your nozzle. Which in area is still 30% difference.
Hi guys,
I have closely followed the topic and almost looks like a witch hunt (no offense to witches)
What speeds and temperatures are you doing the underextrusion tests? (I think it's 230ºC!?)
I got the idea that you are also a UM original user, are you using the same setup temp/speed of the original? The UM2 is my first 3Dprinter (such a newbie!) but it seems that the UM Original can have a nice flow at lower temps better than UM2, however the nozzles are different so in my humble and newbie opinion we can´t compare the two. So bottom line are you sure that you aren't trying to extrude to cold?
I had underextrusion my self, but after this modification, http://umforum.ultimaker.com/index.php?/topic/4319-prints-quality-improvements/page-2, the underextrusion problems disappeared. So am I the one who use higher temperatures to disguise the underextrusion problem or it's you that is printing to cold? maybe its me.. :mrgreen:
Almost everything was checked except the teflon coupler and now the latest theory, nozzle thickness, so it gets to be hard to find culprits when everything has been revised ...
Good luck in your quest
Okay I just looked at your picture, nico and calibrated it using both the nozzle outer diameter of 6mm and opening of 8mm. I get that your nozzle hole is smaller than mine by 30% to 60% area.
Doing identical comparison, metal to metal, I get that my hole diameter is .49mm and yours .38mm (that's where the edge curves inward into the hole).
Comparing the blue filament in my hole - blue edge to edge - comparing that to your nozzle hold metal to metal I get that my hole diameter is .43mm. Either way my nozzle hole seems larger than yours by a significant amount (at least 30%).
This technique of course could use some accuracy improvement! It's hard to say exactly where the edge of the hole is. I tried the same technique for both photos, but differences in lighting can change where it looks like the edge is. That photo that showed light coming through the nozzle hole would be the most accurate if one could photograph a ruler at the exact same distance (preferably in the same photo!).
I measured 4 different directions (horizontal, vertical and 2 diagonals). If I use the SMALLEST of my 4 "metal to metal" measurements of my nozzle hole, and the LARGEST of the 4 "metal to metal" openings of your nozzle hole I still get .46mm for my nozzle versus .40mm for your nozzle. Which in area is still 30% difference.
But that's just crazy. 30% difference for such a delicate precision part seems unbeliveable. But I want to know for sure.
I'll try two things tomorrow.
1. I will try to take a photo with filament inserted into the nozzle to provide more contrast (like the first photo you posted).
2. I'll empty the nozzle, disassemble the head and take a photo at a straight angle through the nozzle.
If I am lucky, the teflon part could arrive tomorrow.
Hi guys,
I have closely followed the topic and almost looks like a witch hunt (no offense to witches)
What speeds and temperatures are you doing the underextrusion tests? (I think it's 230ºC!?)
I got the idea that you are also a UM original user, are you using the same setup temp/speed of the original? The UM2 is my first 3Dprinter (such a newbie!) but it seems that the UM Original can have a nice flow at lower temps better than UM2, however the nozzles are different so in my humble and newbie opinion we can´t compare the two. So bottom line are you sure that you aren't trying to extrude to cold?
I had underextrusion my self, but after this modification, http://umforum.ultimaker.com/index.php?/topic/4319-prints-quality-improvements/page-2, the underextrusion problems disappeared. So am I the one who use higher temperatures to disguise the underextrusion problem or it's you that is printing to cold? maybe its me.. :mrgreen:
Almost everything was checked except the teflon coupler and now the latest theory, nozzle thickness, so it gets to be hard to find culprits when everything has been revised ...
Good luck in your quest
All extrusion tests were performed at 230°. And yes, I had an UM1 but I sold it before ordering the UM2. I also deleted all Cura settings from my Mac. Given that other users printed with the same settings but with different outcomes, there's got to be something off.
I also printed while holding the filament right below the extruder. This produced the best results so far. But after adjusting the knurled bolt I now get underextrusion right after the 3mm^3/s ring. I assume the extruder pushes now with full force (also repated the extruder pulling force test) so the problem must be further up (bowden tube or head/nozzle).
By the way, anybody tried to print without the bowden tube? I'd like to remove just to rule out the possibility of a deformation inside the tube. But I imagine without the bowden, the filament would just bend upwards and not move into the head. Maybe if I guide it by hand during printing.
Humm... so I suspect that your printer doesn't have a problem or defect maybe it's just like the others.
If you increase the temp the underextrusion should dissapear, but is this bypass the problem?
The UM2 nozzle seems to be shorter than UMOriginal so at higher speeds the filament spends less time inside the nozzle and maybe the layers are being extruded colder than an UM original, so if we increase the temperature should avoid that. If this theory is right, underextrusion should be worst at 0.2 layers and thicker layers.
It seems that UM2 nozzle was design for print quality and that may affect high speed prints, it's a compromise and I am very glad that they choose print quality over speed (or maybe it was just a design error) 
This is what works for me:
0.1 layer
20mm/s - 220ºC
30mm/s - 230ºC
50mm/s - 240ºC
100mm/s - 250ºC
If I lower the temps I will have underextrusion, except at 20mm/s I can go lower if want.
If I have to guess George aka Gr5, has a bigger nozzle hole than you, but doesn't mean yours isn't 0.4mm. Now I am curious to see who has the bigger nozzle hole, or if was just a measuring error...
You can stick a needle into your nozzle, and when the needle stops you can mark with a thin pen (or tape) and then measure with caliper the needle thickness on that needle mark
Eih good luck on that
If I have to guess George aka Gr5, has a bigger nozzle hole than you, but doesn't mean yours isn't 0.4mm. Now I am curious to see
This could explain Gr5's tests of max extrusion rates. It seems to me that George has a better extrusion rate than the majority. In addiction to that and a diferent PLA material could explaine why other printers can't reach those values
After a succesfull project using my Ultimaker 1, the company i work at got a Ultimaker 2. Using PLA we are seeing the same problems as described in this thread. Using white i got some interesting failures, with the most prominent one a coral reef like effect.
Printing hotter helps as does printing in ABS (which has its own set of problems like warp and delamination).
Comparing the Ultimaker 1 with the Ultimaker 2 the UM2 underperforms. I did a test where i printed cubes 20x20x20mm using red PLA at 220C and weighed them:
What you see is that the Ultimaker 1 can sustain higher extrusion rates. While the UM2 creates a coral reef at 5mm³/s, the UM1 still creates acceptable results. At 7mm³/s you start to see underextrusion lines and at 10mm³/s holes start to appear. But it is not as bad as the UM2.
While not displayed in this graph, white PLA fails even faster.
So we are a bit disappointed with the Ultimaker 2. We want to be able to use the printer at the 3/4mm³/s range using any color PLA and it gives problems at that speed, while the UM1 didnt.
Here is a tip for measuring the nozzle diameter:
The low speed is aimed at minimizing die swell.
The low temperature is to allow for faster cooling and minimize the deformation due to the extruded thread weight. However, the thread should be smooth and glossy. If it is rough, the temperature is too low.
If the host application does not allow manual control of the extrusion speed, but allow you to send commands, then try:
G92 E0
G1 E30 F60
First code will bring the extrusion length to the origin. It is not anymore relevant if there are absolute or relative lengths.
Second will simply extrude 30 mm with 60 mm/min.
A funny story is about me having discovered that I printed for almost one year believing a nozzle I have is 0.5, to find it was actually 0.4 mm I thought the method is wrong (I found it in reprap world) and test with 0.4 and 0.5 drill bits. It was indeed 0.4 mm 
If you do the above test nico I will repeat it on my machine. Publish the temp and speed used in pronterface and please use the UM light blue filament as we both seem to have that. Do you have micrometer accurate to .01mm? I think I have one somewhere that screws.
I will do this test. But I don't have a micrometer. Only a digital caliper but it should be accurate enough. Regarding filament, I don't have light blue. My UM2 was sent with silver grey because they were out of ultimate blue. Here's the filament I have (only stuff from Ultimaker):
Let's settle on orange. It is very bright and and provides a good contrast to the nozzle color.
Digital caliper (0.01 mm) should suffice. Also, it is advisable to measure using the narrow part (at the tip of the outside jaws). This will avoid errors due to imperceptible curls in the thread. However, the caliper should be in good mechanical condition. Look against a reasonable light source to check if the jaws close uniformly along the edges, and if there is angular play.
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I didn't read through the complete thread, therefore it might have been already discussed:
Have you measured the diameter of the filament and checked if this fits to the material-setting in UM2.
A gap between these two might also cause underextrusion problems ...
Just thinking...
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