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Please update your settings to include "taiwan" in your location. Sorry it's out of warranty. First you should get a multimeter and work with someone who knows how to use it. Again, the resistance should be 108 ohms at 20C. The machine is probably seeing a resistance > 1000000 ohms. so anything from 90 to 130 ohms should be expected. Disconnect the wiring at the bottom of the board under the printer and measure there. If it is correct then the problem is at the board or the connection there. If it is bad then measure at the screws, measure at the pads, measure at the tiny tiny resistor. Most likely it is at the pads where the screw connector meets the board. They may look fine but may need more solder. This is pretty easy to fix. Some people gave up and bought a PT100 part (any PT100 part will do as they all have the same resistance/temperature curve). Then they glued the part down somewhere else and ran wires from the part to the pads. PT stands for platinum.

Sander thinks maybe we should get rid of the 3 post rule and Ultimaker should start selling penis enlargement pills. What do you guys think?

Ja!

By the way you can tell if it's going to do "one at a time" by moving through the layers in layer view. If in one-at-a-time mode it will show it print one part, then go back down and do the next.

Look at your machine settings "gantry height". You don't want those rooks to touch the cross bars. But if you place them far enough apart at a diagonal you can have it ignore the gantry height settings by setting it to 200mm. Or maybe it's a feature? Have the gantry knock one of the rooks over when it starts printing the second rook?

If you had looked at the part in xray view it would have shown errors in red. Any red is where you are looking through an odd number of planes which means there is either a hole in the part or an extra wall such that there is no inside and outside. You probably could have fixed this with some combination of the 4 "fix horrible" checkboxes in expert settings.

The UM2 issue is probably mostly a firmware issue which shouldn't affect UMO. I hope. It hasn't been figured out yet. Your basic problem is underextrusion. The one key parameter you didn't mention is printing speed. Underextrusion may be happening everywhere but it is always most noticable on solid layers other than the bottom layer (bottom most layer depends too much on leveling and so don't use that layer as a judge). Walls aren't always obvious when underextruded if the underextrusion is low enough (say < 25%). In general the easiest way to fix underextrusion is to raise the temp (I recommend 240 as the top temp though - but 240 is a reasonable temp to print PLA) or slow it down (I don't know how fast you are printing? How fast?). At 200C filament is like toothpaste. At 240C it flows like honey. So either go up to 240C or cut your print speed in half and see if that helps. Print a small cube. Another fix is to increase flow. You could increase by 25% but the filament might just grind up so that might not be the best solution. If it's truly only the top layer that is a problem then another possibility is that it doesn't have enough support from the layer below. Sometimes it takes 5 or 6 layers to fully support that top layer. For me, .2mm layer with .6mm top/bottom thickness is plenty for excellent looking top layers. Also I usually do 20% infill which supports those top 3 layers. For .1mm layers I also like .6mm top/bottom thickness. There may be a new slicing bug with Cura as there is a ton of people complaining about top layers right now. I'm currently slicing with Cura 13.09 and have no trouble.

@varsanny - Did you also use different slicers? The only changes I can think of in the firmware is that the PID control for both nozzle and bed changed. This affects temperature. You might want to observe the nozzle temperature in the TUNE menu while you are printing to see if it is stable or if it fluctuates. Or just stick with firmware 14.03 for now (I haven't upgraded firmware in maybe 6 months as I'm pretty happy with the current firmware) until someone figures out the problem and Daid fixes it.

This is getting a little crazy because there might be 3 distinct issues going through this thread: 1) Underextruded top layers (the main thread!) 2) Underextrsusion everywhere (the main problem?) 3) Overextruded edges @nicolinux - regarding #3, your orange "people" photo just above this post looks like #3 is fixed with faster acceleration. The edges look better than the cube you printed earlier where the edges were overextruded. You still clearly have underextrsuion - on the top layer if nowhere else. I don't know what the cause is but another solution might be to just increase the flow by about 25% Do you have the latest firmware installed? I don't. Maybe that's why I don't have a problem? The latest firmware changed PID stuff for both nozzle and bed.

I don't recommend replacing the nozzle. It's a very strong part and you are unlikely to damage it. If you cant get the sensor out and you don't mind destroying the sensor you can drill it out, or use a wood screw, insert it partly in and then pull it out with pliers. Or you can drill from the opposite side a smaller hole and then push it out with a paper clip. You can build your own sensor with any pt100 part but if you use solder make sure you use high temperature (all lead 300C) solder and not normal (200C melting point) solder. As far as the other end of the sensor - remove the larger cover underneath the UM2. It's very easy to remove (in fact the entire UM2 is very easy to take apart and put back together - it is designed to be hacked). The temp sensor wire is very distinct - it is a white braided cable with two conductors. And it is connected to I believe "temp 1" or some similar name.

@printerfan - I find it interesting that you think there is an association between 3d printing and asthma. Do you have similar associations with candles or hot oil frying? I sometimes get asthma but it's not much of a problem for me. But I am not a runner specifically because of the asthma. I still get lots of exercise - just not aerobic. I think once I might have gotten a bit of asthma from some candles. I'll have to pay more attention in the future. I have definitely had no asthma from my 3d printer. I have quite a large house and it's not as air tight as it should be.

Wrong temp sensor LTC. If it was the "bed" sensor it would say "bed" in the error message. So it's the nozzle sensor. How old is your printer? If under warranty create a ticket at support.ultimaker.com. These sensors are repairable but they usually fail inside the nozzle heater block. And getting them out can be easy sometimes or at other times impossible without damaging them. Start by disconnecting the wires underneath the UM2 and measuring the resistance. It should be 108 ohms at room temperature (20C). Anything from 90 to 120 ohms should be considered normal. What country are you in LTC? Please update your settings "location" to indicate your country. I could guess Australia but better to mention it explicitly.

I do an "atomic method" or "cold pull" on ALL filament changes. So there is no need to prime until you get the right color. All of the old color is removed completely. I do this even if I might end up using the same color on the next print. Sometimes I'm just cleaning up and putting things (filament) away.

Oh - I should mention that that print of the "people" looks underextruded. Maybe go to 220C or slow it down a little more. Different colors need different temps.

I would expect lower accelerations to give worse qualtiy. I beleive default XY acceleration is 5000 mm/sec/sec (not 1500). 5000 is what my UM2 is now and I don't think I've ever changed it (currently my UMO is at 4000). The reason is it's really bad for the feeder to ever change speeds. The more it changes speeds the worse the quality. If you have high jerk (default is 20mm/sec) and high acceleration (5000 mm/sec/sec) then the feeder doesn't slow down much and not for very long. You want the extruder to extrude at a constant rate - never speeding up or slowing down or doing so minimally. Everytime you ask it to speed up it will underextrude briefly and vice versa. One fix is to just print slow - if you print at 20mm/sec it will never slow down because the jerk setting allows it to make a sharp corner without slowing down. 35mm/sec is *almost* as good quality and so on. So I have 2 recommendations: 1) Keep acceleration high - 5000mm/sec (note that this can cause ringing along the walls on sharp corners however). 2) For this particular print, I recommend printing the bottom and top layers slower (say 30mm/sec) and then printing much faster (possibly 75mm/sec) on all the other layers. You can do this with a plugin. Changing speed on a layer change should be safe because it should print the interior lines first and by the time it gets to the final outer shell it should be at a constant feeder rate speed and everything equalized.

It makes quite a bit of difference on print quality. Don't buy just anything off of ebay. UM of course has good quality filament. Faberdashery in England is pretty amazing. Maybe the best according to many (I haven't tried it). I don't think anyone sells it in USA but fbrc8.com plans to sell some soon (they have some in stock but the web store doesn't have it - I suppose you could call them but maybe easier to ship from england). In australia there is also an amazingly good filament, diamond age. If you want your filament shipped within USA then one good choice is printedSolid.com. They have colorfabb filament. They are a fast, responsive seller of filaments. Beware that other filaments won't fit on the back of a UM so you might have to put it on the floor. Which works quite well actually.

http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide

The edges look overextruded and the center underextruded which is what you would expect if printing somewhat fast because the bowden stores pressure on the filament like a spring and as you slow down for the edges it overextrudes and then when you speed up towards the middle it underextrudes.

I recommend you cut the tip of the new filament at an angle from 3 different angles so that it has a pointy tip. If you don't do this then it can easily get caught up inside the head at several junctures such as at beginning or end of isolator.

Yes probably just a little too close. But you are doing pretty well - this is a good looking bottom layer. I recommend *not* using the bed level procedure and instead just tighten the 3 screws about 1/8 to 1/4 turn each. I would tighten all 3 the same amount.

There are lots of causes of underextrusion. Is the Extruder motor skipping backwards? It's supposed to if there is too much pressure to avoid stripping the filament at the extruder. You can google underextrusion at this site and learn much more but here's a few ideas: 1) Loosening the 4 long bolts on the head can make a huge difference. Sometimes the bowden is just too tight against the white isolator part (you can see this without taking anything apart). 2) One of the common things that gets gradually worse is the white isolator part. Especially at higher temps (>240C). You could take that part out and slide some curved filament though it to see how much friction there is - maybe drill it out a bit. Or order a new one but this part might re-deform every 2 weeks. You can reduce the pressure on this part by having the nozzle in as low a position as possible. 3) Another thing that can get gradually worse is clogged nozzles. The atomic method doesn't always get all the gunk out. You might want to instead completely remove the part and use gas flame to convert everything in there to carbon and then do a few more cold pulls (atomic pulls). 4) As filament gets towards the end of the spool the angle that it enters the feeder gets too much. Consider putting the filament on the floor (that's what I do). 5) Some of the temp sensors are defective and read the wrong temp because of bad connection that gets slowly worse. Test your nozzle temp with PLA using the below video as a guideline... There's 30 or so other causes of underextrusion so you might want to read about them.

One more thought - can you design the part with 1mm walls instead of .4mm? If you can do that then you can print this just fine with .4mm nozzle.

I don't know what your tolerances are on the outside but I think it's sounding like it will print fine with .4 nozzle if you tell cura it is .19 nozzle. You just might need to play with "flow" setting. As far as getting a smaller nozzle - no one sells these for UM2 yet. So it's tricky. You have to buy one from Ultimaker and they are expensive - something like $40 for the nozzle/heat chamber (it's an integrated part). Then you have to have a metal worker put some solder in the tip (tell him it needs to operate at 280C) and redrill it out to .25mm which is the hardest part of all because .25mm drill bits are very delicate. But with the right equipment (lathe or drill press) it's not too hard. Personally I have the opposite - I have the normal .4mm nozzle plus a .7mm nozzle.

I just downloaded your STL. Since the walls are .4 and since Cura insists on 2 passes it slices fine if you tell it you have a nozzle of .2mm wide and shell of .19. I recommend overextruding (set flow to 150%) on this one to get strong walls. They won't be much wider than .4mm. I'm not sure how good the tolerance will be on the walls but better than you might think. Alternatively consider truly getting a smaller nozzle. I recommend .25mm. Or write the gcode yourself by hand? Or give the STL a "top" and then slice it with "spiralize" such that it prints the outer edge .4mm thick with nozzle and shell set to .4mm. I'm not sure what it will do to the two holes though (cups and vases don't normally have holes in the bottom).

There's no arrow on mine to indicate "north" although I think there might be an LED. I'll bring it outside and check to see if it agrees with where North truly is. Does yours point to true north or magnetic north when you are running the apm planner 2 software connected to the apm unit with a USB cable? I ask because for me they are 13 degrees apart. Plus I haven't hooked it up to a laptop while outdoors. I've been able to hover but I'm not sure what happened to the auto calibrate thing. I think it was too windy when I tried that. I guess I'll try that again just to see what PID values it comes up with.