Nicolinux

Just a little update. I was unable to find a belt tensioner that fits the UM2. The clearing between the (long) belt and the sliding block is just too small...

Just look at the extruder and see if the filament is ground down and the knurled bolt turns without grabbing. If you push the filament by hand, it will surely work.

This happened to me too. Maybe the filament was ground down and while retracting at the end of the failed print, it went over the problematic filament part and straightened it a bit. Then for the next print, the knurled wheel could grab the filament properly and extrude.

Well it seems to me that you, Illuminarti and a few others have special UM2 units. No matter what problems others have, you don't. You can print the cylinder test up to 10mm^3/s out of the box, have a firm z-stage, smooth prints with tight layers and whatnot. I am glad you do, don't get me wrong. But I wonder, am I (and potentially others) too stupid to operate an UM2 or is Ultimaker riddled with such glaring manufacturing tolerances? I had only one short period where I could print almost everything without problems (while not crossing some boundaries like printing over 6mm^3/s and quite hot), but before and after that, I had always problems. I do print lots of different models, but not very extravagant ones and still, there are always problems. I know I expect a lot from the UM2 but that's why I bought it in the first place - else I would have saved money and ordered a Printrbot Jr... Sorry for the rant, I am just a bit disappointed. Please don't mind me, and please don't stop helping others with their problems.

Ian is not answering grrrr... why?

Cura is already pretty smart but you know what would be even cooler? If Cura (or the slicer in general) would anticipate the model geometry and either activate the proper settings or suggest them. Some things are (I suppose) easy to implement. Like a printjob consiting of small delicate objects. This job would benefit from features like "cool head lift" or a dynamic "minimal layer time". Or if there are many short retraction moves automatically change the "minimal extrusion before retracting" setting. I mean it would be nice if slicers were that smart. It would allow a lot more people to use 3D printers for everyday things (and not only prototyping).

I think that if you'd print it with 0.8 shells it will be much much better. Also rotate it to the left so the left fan blows on both ears or else you'll have a mangled right ear because the right fan is usless in this case.

For me this happened only once and only in one direction. Bed leveling too close, move z-stage up/down, bedleveling ok. And then it remained that way. Weird.

Ok, thanks. Dang! None of my old belt tensioners fit so I'll need to scout for a very thin one that won't fall off and destroy the respective axis.

Simon, Could you test your belts and see if then have matching tension? thx.

Thanks Cleven, I'll take a look at the filament when a blob occurs again. Right now I have the suspicion that it happens when I start another print before the printer cooled down. Will keep an eye on this too.

Hey Ian, Try airbnb next time. For Wiesbaden I found places to sleep for as little as 20€ (just searched on their site). Might be a nice alternative except for if you own an extremely comfy pimpmobile

Forgot to mention - I think something got between the screw and the thread. I took it out, put it back and now it behaves normally. The gap between the base plate and underside is 14mm wide.

@Illuminarti: Printing at 0.2mm layer height and 1.2mm top/bottom -> 6 layers (without infill). The 20mm cube is fairly small, I think the UM2 should handle it properly. I'll try some belt tensioners. I have a wide array of failed and still good tensioners from my UM1 trials

Well if you mean this image, then yes, it ok. But this is just the begining of the cube where only 2 layers have been laid down: When the cube is finished it looks more like this and that's not ok: Ok, I understand thx. Of course! I shouldn't throw my UM1 experience over the board now that I own an UM2... I didn't think of it, sorry. Now after tightening the short belts (loosening the motor, pushing it down and tightening the screws), my cube looks like this - only a wee little bit better: Ha, routine under-extrusion sounds so cute - like holydays, ice cream and singing campfire songs in the midsummer night. Not to be confused with monster under-extrusion with extruder skipping that drives one mad.. I tried that too. Normally I print with a filament diameter of 2.9mm (and the orange filament has 2.86mm). If I set the exact diameter, the cube looks like this: Again, a wee bit better, but not gone. Isn't it possible to have no gaps on the top surface? Am I imagining things? I went through some of my old prints, and sure enough there are many with tight top surfaces. Btw. I also printed with a different orientation and the gaps are still there: But I noticed that the long belts do not have the same tension. The sliding blocks are supposed also work as a belt tensioner. But how would one adjust them?

Yes, but only serve it to your friends you like least

Just a little something. ColorFabb's 404 page is hilarious (only for 3D printing nerds). Just wanted to mention it since it shows a bit that they understand this tech well enough to make fun of errors related to it http://colorfabb.com/shop/thisisnotthepageyouarelookingfor @colorFabb: Reminds me a bit of this one: http://blog.camillechurch.com/wp-content/uploads/2013/01/Github-404-624x277.png Now how cool would a broken star wars themed print be?

Hi Cleven, Sadly it doesn't. For me this issue happens when I start a new print after where the previous print was successful. And before the blob occurs, the nozzle oozes quite a bit while moving to the start location - as with any print. I know that moving material fixes it, but this issue is random and I would like to print without having to always move material before starting a print.

For me this issue happened gradually over time. I didn't notice it first because it is only visible on flat surfaces. But it now seems to get worse so I suspect there is something degrading somewhere. Another thing I'll try. I'll rotate the calibration cube to see if the diagonal lines behave differently at different angles.

Hehe, I hope not. I am a very positive person so no bad vibes here. I do live through some sh**ty times right now though, but 3D printing is my hobby and my joy and helps me to relax (except when my UM2 toy is broken - then big drama ensues...). That's why I am so sensitive to every bit and niggle. The upside though - I hope to help to improve the UM2 through my debugging

Same here, happens with different filament colors and brands.

Ultimaker 1 or Ultimaker 2?

Hi Markus, I'll try increasing the flow although I don't like it. Fiddeling with the flow seems to be to be more of a bandaid solution because it whitewhashes all kinds of problems and does have a few side effects too (like overextrusion visible on vertical walls). Ideally I'd like to get to the bottom of the problem and not just patch the outcome. It worked before so it must be something else that either degraded over time or something that changed (filament, slicer, room temperature). I tried different filament brands - that's not it. I'll try different Cura version next.

Hi, I found this odd behaviour when starting a print and the first thing that gets extruded is a big blob of plastic. After that the print fails (almost always) because there isn't enough filament comming out of the nozzle. And the little filament that comes out does catch the nozzle and the whole mess gets dragged around and prevents a clean first layer. Obviously this is an issue with small(ish) objects because there is not enough time for the filament flow to stabilize. But you know, I demand the UM2 to be perfect for small and big objects The first time I posted about it (including a video) was here (http://umforum.ultimaker.com/index.php?/topic/3976-almost-always-missing-layers-underextruding/?p=42399). Illuminarti hints at a firmware bug (http://umforum.ultimaker.com/index.php?/topic/3976-almost-always-missing-layers-underextruding/?p=46653). I wanted to document this issue because it is annoying and because I guess it happens to other people too. It would be interesting to see if it is only restricted to the UM2 (if not, I'll edit the title). Here is a picture of the mess: I know how to avoid it - moving material (menu -> maintenance -> advanced -> move material), but that's not a real solution, just a hack. The usual workflow with this issue is like this: Start print, see the blob, hear the extruder skip once Swear and abort print Remove the mess from the bed Start the print again -> works (never had two blobs in a row) So, hands up. Who had this issue before and wants to kick it (the issue) in the nuts? :angry:

Hi, Another week, another weird problem. Lately my prints started to feature top layers where the filament strands won't touch each other. It looks something like this: At first I thought it might be due to the bed leveling beeing off - because of the big gap between nozzle and the previous layer the filament strands would get streched too thin. I posted about it here (link). In the process of troubleshooting this issue I noticed that my left and right y-rods did move a bit back and forth (backlash). Was easy to fix (loosened the top most pulley(s) and moved them far out so they would touch the ball bearings, then re-tightened them). Now there is zero backlash but I still get the patchy top surface: It seems to get worse with increasing z-height. The first two layers are fine (ok this is because the first layer is squashed and fills up the gaps between the filament strands), but then it gets worse: I found this old post (link) which seems to indicate underextrusion (UM2 underextrusion alarm goes off!!! - where is the <blink> tag?!?), but nah, I don't think it is underextrusion, because I would see it on vertical walls too. Any ideas about the cause? This is on an UM2 with the standard extruder printing at 230° and around 40-50mm/s.