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Right. It makes it much quicker to change nozzle sizes, change to a new nozzle (they are about 11 euros each) or take it off for more careful cleaning. Even though the nozzle is mostly clean it might have some baked on crud along the inner walls. So theory 2 and 4 are probably wrong. If you have a hypodermic needle, or acupuncture needle or 0.4mm drill bit, then you might be able to clean the nozzle out a bit with something like that. In the past I've placed the nozzle in a gas flame holding it with pliers but be careful not to melt the brass. There is a huge temperature difference between burning out everything in the nozzle to ash and the temperature where brass melts. But it is still possible to melt your heater block so I would remove from flame often and check to see all remaining residue has burned away. Then test by pushing some pla through it while it's still hot and still held by pliers.

There are many factors that affect the final dimension but they tend to be consistent even when changing filaments. The biggest shrinkage is on vertical holes and is caused by the PLA acting like a liquid rubber band as it is being laid down. It shrinks quite a bit in the first millisecond but is still liquid and so it has tension and is pulling inward. This is difficult to compensate for in software but you can do it. Rather what I do is in cad I make the vertical holes a bit larger. Also I often make small test prints for pieces that need to fit together. After a while you get really good at it.

This problem came up last summer as well. And also with someone in Brazil during their summer. The heat isn't bad for the stepper motors - but it makes PLA soft if the PLA gets above 52C. If you are printing ABS and want to raise the air temp to 50C inside the printer the steppers should be okay but any hotter and you should probably put fans on all three steppers on the inside of the machine (Z stepper should be fine).

Um - a video would help. Are you sure the click isn't *causing* the retraction? Are you sure it's an intentional retraction? Because what you describe sounds like the kind of click that you hear when you lose some steps. It happens all the time when there is too much pressure. 210C, 50mm/sec is fine as long as you are doing .1mm layers. At .2mm layers that's too much and so you need to increase the temp (pla is more like honey at 230C and more like toothpaste at 190C). here are my recommended top speeds for .2mm layers (twice as fast for .1mm layers): 20mm/sec at 200C 30mm/sec at 210C 40mm/sec at 225C 50mm/sec at 240C The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA.

How long did you have your printer before this started happening? Are we talking a few months? A few years? What country do you live in (please update your location settings). theory 1: That black stuff is very worrying in your cold pull. You probably have a thin layer of gunk inside your nozzle which is making it smaller. Could that black stuff be pieces of of black nylon from the feeder? You might want to replace the nozzle. Or take it out and burn everything out of it and even maybe soak it in acetone for a few hours. Or get a Olsson block and new nozzle. theory2: teflon Isolator - these kind of die after a while. Easy to test if you have an olsson block as you can push filament up from below through the isolator to feel the friction. theory 3: Some prints have too many retractions two close together and the filament gets ground up. Next time this happens pull the filament out a bit and check the portion that was in the feeder to see if a bite has been taken out. Or if it is flattened. Some prints I've had to reduce retractions by setting the min-distance to .3mm (that means no more than about 15 retractions for a given spot of filament). theory 4: People in warm climates have issues when air gets above 30 or 35C because the filament gets soft at the extruder. Is your room temp higher than a few months ago? The fix is to put a window fan blowing on the extruder to keep the shaft 5C cooler. I can come up with more theories if you rule these out.

I see you are in the UK. Someone else in the UK have a recommendation? To clarify - on UMO you enter the diameter of filament in Cura. On UM2 (assuming you are printing ultigcode mode) you enter the filament diameter on the printer in material settings. I have to tell you - the micrometer is the most useful tool I have when I design prints in CAD.

I see you are in the UK. Someone else in the UK have a recommendation? To clarify - on UMO you enter the diameter of filament in Cura. On UM2 (assuming you are printing ultigcode mode) you enter the filament diameter on the printer in material settings.

Yes. I had the same thought. The frequency is around 10 or 20 times per second (you can see the LEDs flashing on the UM2 when the bed is close to the correct temperature - that's how I know the frequency). 25-50ms (the "on" time) might be long enough to make the power supply "barf". Or maybe not - there might be a very large capacitor that can handle increased current for that long.

@dantman - which version of cura is this?

What's an "OU"? Original Ultimaker?

You probably don't have the right drivers but start here: https://ultimaker.com/en/community/view/6100-how-to-update-um2-firmware#reply-47156

That's too cold for ABS. I recommend at least 100C. 110C is better if you can get the bed that hot - I had to enclose my printer to get up to 110C bed. The glass temperature for ABS is pretty close to 100C and you want to be a little above that to avoid parts from lifting from the bed. Also this helps heat the air around the part somewhat.

I'm really not an expert at ABS bonding. I've been told that .3mm layers is too thick because you don't get good contact with the layer below (traces of filament being layed down are too round so you get air gaps). However it seems to me you want thick layers so you have plenty of hot ABS heating the layer below (thicker layer should mean more heat is transferred to get the below layer to melt more). So I would expect .2mm layers would be better than .1mm layers. But I could be wrong - it might be that .1mm layers works better because the hot nozzle is closer to the lower surface? I don't know. Certainly higher temperatures help, enclosing the machine so the air around your part is at least 40C should help, zero fan or very little fan should help. But I have gotten nozzle clogs when I print too slowly at 255C so I try to avoid going over 250C or if I do I make sure I'm printing more volume per second (e.g. 35mm/sec .2mm layers should be enough but 35mm/sec at .1mm layers is too slow).

Even for firmware upgrades?

It was no trouble - I had to make edits in that part of the code for another experiment I'm doing anyway. Maybe you should know that there is also a setting in configuration.h: #define PID_MAX 255 Just for this kind of thing (power supplies that can't quite deliver) to keep the power down a bit on the nozzle. I'm not sure but if you alter that one you should alter the line above it also: #define BANG_MAX 255

You probably need a much bigger piece of tape than the area you are printing on above. This allows a much larger area for the tape's glue to adhere to.

Wow! That sounds like a ton of work! I have no idea how to do that.

So it separates on layer boundaries? Like if you print a vertical 10mm cylinder with .8mm wall and no infill you can easily snap it in one hand?

Well that right there is very messed up. The first line of code that mentions "ultigcode" is somehow not being read by the printer. Did you say you were able to print other things on the SD card? This is very very strange. Yet you were able to locate your print job on the SD card, right? did you use the SD card that came with the printer or a different type? I don't think the arduino chip can read just any SD card. You should stick with the one that came with the machine. Maybe there is a loose cable. There are 2 ribbon cables that go from the main PCB to the display PCB. I would re-seat those. Start by removing the bottom cover. There are just 2 screws holding that in. Locate the 2 ribbon cables and fiddle with them a bit. Next remove the smaller cover underneath and then take the display out (it's tricky don't force anything - I forget how to do it but I remember it confused me for 10 minutes) and reseat those cables. The whole thing comes apart without much force and only using 2mm hex wrenches.

Did you push/move the head while it was paused? If you abort, then it has to re-home again before it knows where it is. Is the print head smashing loudly into the left wall? If so there's something wrong with the limit switch - it's probably not quite making contact. With power off try to push it so that you can hear the click of the limit switch when the head is all the way over to the left. You might have to bend the metal tab on the switch a little or maybe the fan shroud is bent and the fans are hitting the wall before the limit switch is hit.

Some day HP will make a home 3d printer that is as easy and reliable as their 2D printers. It will have a built in video camera (or 3 or 4 cameras) and will auto level based on the video results and know if the nozzle is jammed (video) and will calibrate and self test things like max acceleration without missed steps (all with video feedback), how much retraction is needed calibrated live as you print, best printing temperature live as you print. If part is sticking well or comes loose, the printer will stop immediatley. If you run out of filament it will pause and so on. It will talk to you like siri. It will have an amazing slicer built in that handles support issues perfectly with break-off (or disolvable) support. it will be 100 times smarter than cura. But this is in a time in the future that I have not yet glimpsed.

You are getting quite reasonable results now! Congratulations - I'm glad you got this printer "tuned in". I recommend some kind of top cover as well but one that lets a little air out the back so it doesn't get > 50C.

Can someone confirm if the latest version of Cura (>15.06) still has the USB driver?

Yes. Probably. This may be a recent bug in Cura. Do you know what version you installed? I recommend 15.04. I just installed it now and it prompted me to do the USB driver at the end of the install process. It's fine to have multiple versions of Cura on your machine. They don't overwrite each other but instead exist as completely different applications.

gcode looks fine. Is this the file copied from the SD card? I'm thinking maybe you pulled the SD card out of your computer before it finished copying? maybe you should backup the SD card and reformat it.