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In Cura - make sure retraction is enabled ALWAYS. Must set blue circled things to 0 On ultimaker, set retraction to higher value than 4.5. I don't know what value to use as I am still new to UM2. There are 2 ways to do this - you can modify the PLA settings permanently or you can just modify for one print. Here is how to do it for one print:

Lol! I am confused. You explained several ideas but never said what you actually did. The purple section is PLA, right? What is the white section? PLA90? ABS? This is very clever! I really like this idea! Especially the zig-zag triangular seperation between white and purple.

Consider using some teflon plumbers tape. Other's have used this to help seal the threads in the hot end: http://en.wikipedia.org/wiki/Thread_seal_tape Apparently it can handle 250C no problems. edit: teflon melts at 600K or 327C.

Die wichtigste Eigenschaft ist, dass es <3.000 mm. Wenn Ihr Filament 3.01mm, es wird ein Problem für Ultimakers sein. Es wird in der Röhre stecken bleiben. Die zweite wichtige Eigenschaft: Keine Partikel> 0,1 mm, die die Düse verstopfen können.

Normally 75mm/sec speed is fine but if you want to reduce stringing it helps to print slower (20mm/sec) because there is less pressure in the nozzle. You probably can print this at 75 but I would try 20mm/sec first. Also heat is your enemy for stringing so if you can print on a cold bed instead of heated bed and print on blue tape instead of glass that will also help but I think that you will be okay with a heated bed.

Yes, that's where and how you place the flyback diode. Do you know/can you measure the current draw of the current existing fan? That would tell us a lot. You would need to insert a current meter in between the fan and the controlling circuitry. Or maybe someone posted this info somewhere. The other issue is I don't know if those air valves you linked to will output variable control if you feed it a pwm signal. They are designed to take a variable voltage/current. Not a pulsed voltage/current. But I'm guessing it will work okay. It worked for the fan anyway!

Damn. There is no flyback diode on the fan circuit. You need to add that. You need to add a diode - the smallest you can find will be large enough. Personally I would rip one out of my old electronics pile. You want it to allow current to flow from pwm1 to pwm2 (see the 1.5.7 schematic). This will happen every time time Q4 switches from on state to off state and if you don't do it you can get hundreds of volts on Q4 and you can damage it. http://en.wikipedia.org/wiki/Flyback_diode schematic: http://reprap.org/wiki/Ultimaker%27s_v1.5.7_PCB You will need eagle software (free) to view the schematic: http://www.cadsoftusa.com/download-eagle/

You don't need to convert to current. If you get the "0-10V, max 12.4V" version it comes with an internal coil resistance of 54 ohms. So the current will be voltage/54. So 12V will give you 12/54 or .222 amps (222 mA). The max current draw would be around 222mA. I don't know how much power that head fan pulls at 12V but I'm guessing it's similar. So you might be okay with no wiring changes. Find out how much current that fan pulls or how many watts it is. That fan *is* a 12V fan, right? I just checked the schematic. Yes it's a 12V fan. The worst you can do is overheat Q4 and then you can just replace it. But before spending the money for that valve I would check how much current the fan draws. That darlington (Q4) is one of the more common parts to fail on the UM so it is already operating near the limit. Hopefully your valve uses less power than the fan.

Regarding the graph above, those numbers I posted were kind of wild guess memories that I know are safe to print at. However there is a little more accurate data here: http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/?p=13194 And Illuminarti did some interesting tests with a .65mm nozzle here: http://www.extrudable.me/2013/04/18/exploring-extrusion-variability-and-limits/ I recommend scrolling down to his graph. .65mm nozzle has 2.64X the area of the .4 so you might have to divide all his values by 2.64? Or maybe not quite 2.64 as maybe his limitation is the power of the heater to melt versus the hole size? Also I did some tests on the UM2 for extrusion rates: http://umforum.ultimaker.com/index.php?/topic/3418-um2-extrusion-rates/

In the UK, any PLA you leave in the car all year round will not survive. I suggest you get PLA90. ABS is more difficult to print and you practically are forced to get a heated bed that can go to 110C if you print ABS prints more than 2 or 3 inches long. PLA90 I believe is even easier to print than regular PLA I believe as I think the thermal coefficient is better (less shrinkage).

You can adjust a little bit - if you take it all apart (while hot!) - after removing the nozzle, screw the threaded tube further in from the top so that it goes further into the aluminum block (the peek part will be much closer and there will be a shorter cooling distance but it should be fine).

My um2 came default settings for PLA retraction to use 2.5mm. That's not enough. Change that to at least 4.5mm. Someone with a UM2 suggested even more - I think maybe 5.5mm but whatever your retraction is, increase it slightly. 190C and 20mm is very smart. This is a good setting. DO NOT use "default" settings or easy print settings or whatever they are called. Only use expert mode and make sure "retraction" is enabled. Also set the other retraction parameters in expert settings to 0. So minimum extrusion should be 0. Minimum travel should be 0. Otherwise it won't retract at al. Even a minimum extrusion of .1mm translates to 4.9mm of movement if your layer height is .1mm and some of your extrusions for this bracelet look smaller than 5mm. So set these to zero!!!

Many of the old plugins that worked fine for Cura 13.04 and older broke when Cura 13.05 came out. This is because Cura now uses G0 for it's move code when changing height but the older cura used G1 for the move command (they do the same thing in the UM but other printers different). So you need newer versions of all the plugins. For example this one works great: https://github.com/Dim3nsioneer/Cura-Plugins/blob/master/TweakAtZ.3.0.py That one even now takes care of if you are printing many objects in the same build plate (but one at a time). It resets and does the same tweakAtZ on *every* print - not just the first one.

I never use those - even on the first day I got my UM I started playing with all the parameters. There is a relationship between temperature and speed. If you print hot like at 240C you can print fast like at 100-150mm/sec with .2mm layers but you might get a little underextrustion and you won't get quite as good quality and also you will get TONS of stringing. If you print real cold like at 190C you can't print much faster than 30mm/sec but at 20mm/sec I get very very good quality (still talking .2mm layers) and you will get almost zero stringing. If you try to print cold and fast you will get severe underextrusion (lots of pressure in the nozzle) and likely filament grinding and slipping.

The newer firmware heats the bed to 90% before starting to heat the nozzle - this way they supposedly get to temperature at the same time. I'm not sure if the timing is always perfect though.

Yes. And add a drop of thin oil without getting any oil on the knurled bolt: This video from peter is great - start about 50-60 seconds into the video:

Just do it half way between how it was and how it is.

It will always be as loud as a dishwasher which is too loud to sleep by but okay for watching television maybe. Some time when your printer is printing, grab the extruder drive and remove it from the back of the UM (yes, *while* printing). Notice the change in volume of certain pitches. Then re-attach. It gets louder. This part can take away that sound but not the other sounds: http://www.thingiverse.com/thing:53690

I also recommend Drayde remix.

Amazing photo. It could be other things but it sure looks like a Z issue. I would disassemble the Z screw. Check to see if it is straight. Lay the z screw on a flat table and check it carefully by eye.Slide the bed up and down without the z screw. Also see if the z screw lines up perfectly with the coupler.

Why do you print 190C? That's quite cold for PLA. I recommend trying 220C or 240C. Don't be afraid to try a little hotter.

He saved the video in 4 formats. Same video. 4 formats. One of them should work for you. They all worked fine for me.

PM illuminarti about nozzles.

I had to stare at the photos - they are a bit blurry and also dark. But I'm 80% sure this is underextrusion in the walls. Easily fixed - just raise the temp to 240C or lower the speed to 30mm/sec. Try one or both of those first to see if it makes a big difference. If so then what temp and speed were you printing at? You may need to tighten your extruder spring but first lets get it to print better.

So will someone send the recording to Harma?