gr5

DM=Direct Message To do a DM click here: http://umforum.ultimaker.com/index.php?/user/423-sandervg/ Then click on "send me a message".

you only have to loosen two pulleys on the long belts on each axis. If only one axis is messed up you only have to loosen 2 pulleys.

No. You don't. I want to see your part in layer view and in normal view in Cura only. I do not want to see what it looks like printed. You already told us the layers are missing in cura slice view - so why would you then print it and be surprised.

I also like the recent idea of always overextruding bridging such that there is enough plastic to create a .4mm diameter string (equivalent of .4mm layer while in the air but not when over other layers).

That would be very nice!

What fingerpuk said. I recommend putting the filament on the floor. This rubbing causes problems and slowly grinds up the black ABS plastic that the feeder is made out of and that ABS plastic gets dragged eventually into the nozzle where it causes serious problems in the nozzle such as blockages or reduced ability to extrude.

The brass nut I was talking about actually isn't visible from the bottom. You don't have to take anything apart - just raise the bed and look at the 4 screw heads closest to the big Z screw from below. Make sure those 4 screws are tight. That's all. This was a problem for someone else who was constantly losing his level due to the bed being loose there. Personally once I set my Z level I don't have to touch it for a month.

I don't understand about loosening screws. Did I say to loosen screws? The 4 thumbscrews should be tight. The bowden itself can be locked down better if you want but isn't mandatory. I think I suggested a longer retraction distance (more than 4.5mm - maybe 6mm is right for you).

If there is wood debris you can usually see it by removing filament and looking into the feeder with a flashlight - you don't have to take anything apart. Test boiling by touching a drop of water to the aluminum block. Use finger or qtip ear swab. Also room temp should read about 20C when the machine has been off for 30 minutes.

Swapping from ABS to PLA takes lots of experience and practice but usually results in clogged nozzles. You might want to remove your nozzle and burn out all the plastic and then soak in acetone. Certainly you want to get all that ABS out of the bowden and out of the feeder before you start a print. ABS, if kept hot for too many minutes slowly cooks into a very difficult gunk that will require special effort to remove from the nozzle.

This is a common problem on the UM2. I suggest you go over to this thread and print this test piece at 230C which will test out your thermostat, extruder path, feeder, bowden, filament, everything at once. It is *critical* you test at 230C even if your problems are at 210C. http://umforum.ultimaker.com/index.php?/topic/4586-can-your-um2-printer-achieve-10mm3s-test-it-here/

Something is wrong with homing. You need to check 2 things: 1) With power off and the bed in the up position look underneath the bed at the brass colored nut that the z screw goes through has 4 screws holding it to the bed. Make sure those are all tight. 2) Sticking out of the bottom of the bed should be a very long (30mm?) screw that sticks down. When the bed lowers it goes down through a hole in the bottom of the UM2 to hit a switch. Please examine that switch. If you lower the bed by hand with power off, does it touch the switch and make a click sound? Consider putting the UM2 on it's side so you can look at the switch as the screw hits it. 3) If the switch seems fine, consider removing the larger cover on the bottom of the UM2 (only 2 screws hold it on) and check the "z limit" signal as the wire traces from the z limit switch to the connector on the printed circuit board. When you start levelling it does a Z-home procedure where the bed goes all the way down. Does it make a horrible death rattle sound at the bottom? Or does it click the z home switch gently twice?

Good catch. I set mine to zero because I have never had my filament grind to dust (on the UM2).

If you ask nicely, UM will give you a free second nozzle. Offer to pay for it and they will likely refuse your money. Step 2 is to modify the nozzle for .25mm opening - maybe talk to a machinist or go to a local fablabb or makerspace and see if you can maybe solder the hole closed and then drill it out again. I have 2 nozzles for my UM2: .4mm and .7mm Unfortunately it is not easy to swap - it takes 20 minutes or so although I get faster each time.

Nice excel graph. It would be interesting to also include layer time - Cura simply assumes 100% acceleration and determines it based on print speed and total length of all lines on a layer. Again: Did you hover over the settings in Cura? It explains how this works. Again: For PLA you should be using 100% fan for min and max. For ABS, lower fan speeds make more sense. To answer your question - if you hover over the "max" fan speed it says it increases fan speed to MAX value as layer time adjust speed by 200%. I think Daid means 50%. So the point is that as print speed approaches half of nominal speed, fan speed should approach MAX speed. You could test this by starting the print with a higher print speed and then graphing it in excel again.

On my brand new UM2, 4.5mm (the default) wasn't enough. It needed more like 5.5 or 6mm. 5.5mm was enough for me. After I secured the bowden better (a month or two later) I was able to reduce that to 4.5mm. Try increasing your retraction a bit. Also for some filaments I have to lower the temp to 190C to eliminate stringing but that may mean printing even slower. Although usually 210C is plenty cool enough. Also make sure your travel speed is fast - 150mm/sec minimum - try 250mm/sec. This helps break the thread/string. Moving at 250mm/sec is not a problem for pretty much any 3d printer out there - it's the acceleration where the UM is so impressive.

Definitely remove the 4 long thumbscrews first. Changing the fan is the easiest thing to do on that head. Easier than messing with the nozzle even. To see the fan connector you don't even have to do that, just slide up the black mesh and you can see all 3 fan connectors in there. When removing the 2 screws holding in the heatsink be careful as the spring in there (it's obvious) is pretty strong so squeeze it together with one hand while removing the 2 screws with the other. Click "raw" to see the um2 assembly manual: https://github.com/Ultimaker/Ultimaker2/blob/master/um2%20assembly%20manual%20V1.1%20_english.pdf

Could be lots of things. The first thing that comes to mind is that the first layer or two are printed slower. What speed are you printing at (the speed isn't important - it's the volume of PLA per second - so whats the layer height and speed)? And what temperature. It's easier to get filament out at 240C than 220C. Don't say "defaults" as these can change among firmware versions, plus the defaults in "quick print" for example also change between versions, plus I've changed settings so many times I don't know what the default used to be anymore. Have you printed many things before this started? Are you near the end of a reel of PLA? The second thing that comes to mind is tangled, difficult to deal with, sharp curvature filament from the end of the spool. The 3rd thing that comes to mind is clogs - but this doesn't sound like a clog as with clogs it usually only prints a tiny bit each time - maybe for 20 seconds. Not a whole layer. 4th: filament diameter might be 3.00mm instead of 2.85mm. That would cause this. 5: Printing at or below 180C would cause this. 6: If the 3rd fan on the head is broken - that could explain this - it should start spinning when you power on the machine (even before the lights come on) - it's quiet and most people don't notice it - it's at the rear of the print head.

Unlike normal motors, stepper motors apparently use the same amount of current regardless of how much work they are doing. So I assume a hot motor doesn't have much to do with mechanical resistance - more to do with current setting. These stepper drivers are very easy to destroy. But they are also cheap and available from many sources.

Yes. Mechanical issues look different - typically two close together lines and then a gap and then repeat. Better to print slower. Are you sure these gaps aren't on purpose by the slicer? Maybe open the gcode in repetier host (it's free) and see if it also thinks there are expected gaps?

I recommend .2mm layer height and 100% fan both of which help with bridging.

@selmo there are many causes for missing layers. If the model is manifold (that's a HUGE IF as it is difficult to prove) and if there are no walls that are inside the STL closer together than .8mm then there are still several other things that can cause this. It's hard to explain so I'd rather you sent me an STL with issues. For models that are organic - like sculpture the problem tends to be (somewhat) related to your triangles being too small. For mechanical or architectural models it tends to be that walls or corners are too close to other surfaces or corners. Part of what cura does is it intersects a plane with the STL and gets a bunch of line segments in no particular order. This is important: NO ORDER. STL doesn't specify which triangles are touching which. So then Cura takes this random ordered set and tries to link all the lines up. Sometimes it links them up wrongly because they are very close together but not quite and Cura decides "close enough". This causes problems as Cura gets chains of lines that refuse to form loops and so it just discards those and prints nothing.

@ultismoother - you frustrate me. POST PICTURES PLEASE! I asked you several times. Also you don't understand what I am saying about wall thickness. I have seen the problems you talk about. They can be from several known causes. I refuse to say anymore until you post pictures. Even better send me the STL.

Strange. Well that nut with the holes in it rotates - you may want to heat to 180C before rotating - you might even have to disassemble enough to get the spring out to lessen the pressure. Rotating that nut (which is not as strong as steel so take it easy!) raises and lowers the nozzle tip so that if we ever go dual extruder you can set them to the exact same height.

I assume this manual will tell you how to assemble it. I really didn't pay attention to the wires other than to make sure the fan wires didn't get pinched. The manual might not be helpful - I haven't looked at much of it yet: ultimaker2 assembly manual - click "raw" to download the pdf: https://github.com/Ultimaker/Ultimaker2/blob/master/um2%20assembly%20manual%20V1.1%20_english.pdf