Nicolinux, someone else mentioned this nut so I looked at my extruder motor on the inside of the machine and it is flush against the back panel. Please also do this - look straight down from above and make sure the motor is touching nicely.
Nicolinux, I hung out with Sander the last 4 days and he said that he thought your part was shipped out about a week ago. He will not be coherent until Tuesday so wait until then to contact him. I think your package must have been sent to the wrong address.
We are almost to 25 pages! Aaron - Stepper motors have a natural position. When you push hard enough you can overcome the current holding them in place and they will move (click) suddenly into the next position. I'm not sure if this is 1 or 4 steps (I think 4 steps). This is about 1/8 or a little less of a turn on the extruder. Occasionally the pressure against the filament is so high it will go double this (8 steps).
The pressure is indeed mostly in the bowden. These feeders can push about 5Kg which comes out to almost 1000 psi inside the nozzle! Of course it is underextruding slightly (probably about 10% if you look at some of illuminarti's experiments) just before the slip but 10% isn't really very visible. Once it slips back it takes quite a while to recover.
This design is on purpose. The slip is not detected - if it were it would try to recover quickly instead of slowly.
This design is preferred (by me at least) over grinding the filament into powder. Worse, on the UM1 early design it would break something else - usually popping the bowden tube off and scraping it with the metal blades that hold it in place and ruining it.
This whole 90% flow thing is very intriguing. It doesn't make sense to me so it is unexpected and interesting and likely important.
Usually the 90% extrusion is caused by the filament slipping the tiniest bit as each tooth digs into the filament and it slips a little. So the stepper is turning at the 100% correct value but the filament is moving at 90% of desired value. So the stepper doesn't know the filament is slipping.
The whole 90% flow thing is more likely to have something to do with how the filament leaves the nozzle and flows into the corners of the part. With 90% flow it doesn't quite fill a layer completely so there is a tiny space to move into when it is done and there is significantly less pressure.
Have any of you tried to increase the current? It is a trivial single gcocde command. I tried it and my filament ground to dust.
Nicolinux, someone else mentioned this nut so I looked at my extruder motor on the inside of the machine and it is flush against the back panel. Please also do this - look straight down from above and make sure the motor is touching nicely.
Nicolinux, I hung out with Sander the last 4 days and he said that he thought your part was shipped out about a week ago. He will not be coherent until Tuesday so wait until then to contact him. I think your package must have been sent to the wrong address.
Yep, checked it again today. I have even removed the nut and filed it a bit down on one side - just to be sure. Illuminarti and Aaron already hinted it. The nut aligns nicely with the case and the stepper sits flush against the back panel.
Regarding my shippment - I'll wait.
Forgot to mention. I didn't increase the current (because I still think it is not the extruder). But I'll try it.
Well crap. After several hours of reading I find there is no solution. I thought my "geek factor" was pretty high. There are people working on this who are way better than me.
About the extrusion %. I am printing at 107%. Less than that, and any horizontal layer that is filled in with parallel rows get noticible gaps between the rows. Enough of a gap that if I printed a cup it would not hold water.
Just out of curiosity, I ran the extrusion test with ABS at 200% speed to find the flow limit for ABS.
(I am sorry for torturing you, my dear Ultimaker :mellow: )
Interestingly, it was okay up to 12mm3/s (6*200%).
Then is shows very similar behavior as PLA did:
When checking the feeder, it is obvious that the knurled gear is starting to slip at high speeds.
It is not skipping steps, but the marks from the knurled gear on the filament is smearing out more and more the higher the speed is.
The nozzle temperature stays stable at 260C throughout the print according to the control panel though.
Therefore, I guess that the maximum flow rate depends on the flow characteristics or thermal conductivity of the plastic rather than the feeding mechanism or the nozzle heater.
Now, I promised the professor to print a number of things which has to be out of white ABS coming week, so I really have stop using it for tests before I run out of it. :grin:
This whole 90% flow thing is very intriguing. It doesn't make sense to me so it is unexpected and interesting and likely important.
Usually the 90% extrusion is caused by the filament slipping the tiniest bit as each tooth digs into the filament and it slips a little. So the stepper is turning at the 100% correct value but the filament is moving at 90% of desired value. So the stepper doesn't know the filament is slipping.
The whole 90% flow thing is more likely to have something to do with how the filament leaves the nozzle and flows into the corners of the part. With 90% flow it doesn't quite fill a layer completely so there is a tiny space to move into when it is done and there is significantly less pressure.
Have any of you tried to increase the current? It is a trivial single gcocde command. I tried it and my filament ground to dust.
Hi George
As always very usefull info. Thanks
I thought that reducing the Flow % would reduce some pressure and that could improve the extrusion. I think that this is not the solution of my underextrusion problem but this way I could achieve the 10mm3/s. There is more users that could overcame the underextrusion changing the flow % (Shurik was suceed with 80% flow) I can't find any fault on the nozzle head so I will try to increase the current.
Right now I feel as in the begining, and don't now if I have over pressure in the bowden or if is the stepper motor that can't manage "normal" pressures.
Are you always running with higher current, or you just changed to test?
Thanks
I did the extrusion test again today, this time with Grey ABS from cdwriter. It's the first time I've loaded ABS into my UM2. Almost on the first layers it came unstuck from the platform but the skirt seemed to stop it roving too far so I let it run to completion. The result is a total mess, BUT... .. . .
It did run to completion without any skipping of the extruder motor. (258C/104C)
YES!
Teflon coupler get! I'll try to focus now on some iOS client work and tonight is tinkering time!
@WoofysPlace, Anders: Seems that ABS is a total different beast. I'll be sure to tackle it after this issue is sorted out.
OK, after a brief flurry into ABS, I'm now back on Faberdashery Arctic White. While extruding I thought here's another way to measure nozzle diameter: Measure the extruded filament.
The scale says 0.43mm. Over the length of the fragment I measured between 0.39mm and 0.44mm.
Seems my nozzle diameter is ok.
I used the needle method where I marked a dot on the needle with permanent marker just below where it disappears into the nozzle and then measured with calpers like the one in the picture above.
I got 0.40mm +/- .02mm
It wasn't easy - I needed a magnifying glass and I had to make the dot closer and closer until it almost disappeared. It took about 15 minutes.
Are you always running with higher current, or you just changed to test?
I just changed to test. I found higher current means the filament grinds and slips and the print fails which is worse than slipping.
Hi,
I have swaped the teflon coupler with the new one and nothing changed. Or it did, it is slightly worse than before.
Take a look at this (sorry for the direct link, the forum is broken for me right now and won't allow me to upload pictures):
Underextrusion started half past through 3mm^3/s.
I cleaned the nozzle after the test print and noticed that the "inside nozzle" shaped filament bit that I pulled out, had a dent. This is new and I don't know what it is.
The normal filament tip looks like this now (still featuring a lip):
I also noticed that I can't load filament if I don't blunt the tip (sharpen it) before. It won't get past the teflon coupler. The stepper just skips and does not advance filament. I managed once to get past the choking point when I wiggled at the bowden tube. But it didn't work since. Before I assembled everything I tested if filament slides through the teflon coupler. It does and its diameter is 3.15mm.
I will try three more things before I dump this printer:
Guys, thank you for your help. I appreciate it very much. I don't have much hope to solve this issue, but it is nice to see so much dedication.
Stefan
EDIT: Uploaded images
Hmm... I had one of those dents as well when I did a clean out. Didn't think much of it at the time though, figured it was an air bubble after moving the filament back and forth. I'll see if I can find it tomorrow and take a pic.
I am so sorry. Damn your printer is haunted!!
Maybe that hole in the filament tip is from a clog inside the nozzle. maybe abs or other garbadge from the extruder?on other end it's so perfect shape maybe Robert is right and it's from a air bubble. Dumping the nozzle in acetone for a while it's a good idea.
I will try three more things before I dump this printer:
Well, any good show must end with a bang, so maybe this litle guy can help?
(can´t upload new photos...)
Just kidding. Hey cheer up! Keep up the good work and you will find what is causing the problem
Blarp, it's a real bummer to hear you are still having problems with your printer :(. I wonder why you are having an issue getting the filament into the heated nozzle now? I really appreciate all of the effort you put into testing out all the great suggestions in this thread, it should be us thanking you :wink:; I've learned a lot from your experimentation and documentation.
I will try three more things before I dump this printer:
It would be too sad if the thread ended like this.
Hi Guys
Another thought after openning a fine American apple cider! So if you think is stupid, I will claim that I was under the influence :blink:
What about bowden tube lenght? Can a bigger bowden tube increase the springiness effect and cause the motor backwards steps? Can someone with good extrusion rates measure the bowden for comparison?
Edited: Stefan have you seen already the nozzle hole(inside) with a magnifying glass?
Hi IRobertI,
Robert did you also sharpened the filament tip when that bubble appeared? can this be the cause of those "air bubbles"? I always cut my filament on a straight angle and never saw a filament tip as Nicolinux.
Hi Nicolinux,
that is verry frustrating experience with you printer, i hope i wont have to go trough all the problem you had. But why to dump the printer, in the end it was a quite expensive device.
I do have a suggestion for you, dont know did you think about it? Since you are in EU (no complicated customs papers) why dont you pack your Ultimaker 2 and ship it to Ultimaker for inspection/repair? Im sure they would be happy to do it, and they would gain more experience on this problem. Shipping in EU is cheap, so in the end of the day you will maybe pay 35-40 EUR for shipping it in one direction, and im sure Ultimaker would ship your repaired printer back at their cost (any manufacturer with reputation will do this).
Dont dump your printer yet :-P
Thanks guys. With dumping the printer I ment sending it back for repairs or selling it if Ultimker doesn't accept it. That's the last thing I'd want to do because the hacker in me wants to get to the bottom of this problem. But after spending way too much time on this issue (and with my issues with the UM1 still not forgotten) my enthusiasm for Ultimaker starts to wear off.
Your frustration is understandable, but you should have shipped the Ultimaker 2 to Ultimaker office immediately because of the nature of problems. Now they would have only more work to fix it as it has been disassembled many times and possibly more errors have been introduced to the printer system.
I cant say for Ultimaker, but i think they would accept to fix your printer surely. Try to phone them and send them a printer after agreement, you could possibly have your Ultimaker fixed in few days.
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By the way. As a simple comparison. When I still had my Ultimaker Original, I printed the Twisted Gear Lamp (http://www.thingiverse.com/thing:31722) with the following settings - with zero underextrusion:
Filament volume: 8mm^3/s.
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