Nicolinux

@IRobertl: Ok, thanks. But wait a second. Maybe I don't understand your design. Why do you have to make threads to accomodate for thicker rods? I think only the spacer would have to be enlarged and it doesn't have threads.

Oh no, I have only M8 rods and 608 ball bearings at home. I guess you don't have the source files in a noob friendly format so I could customize them?

@AaronAlai: From my experience the UM folks are very generous. They have already sent me a couple of parts for free while I was tinkering with the UM1. I am thinking more about the downtime right now @illuminarti: I think the lip formed because the diameter of the exit hole was smaller than that of the nozzle. When pressure was applied to the teflon coupler, it pushed it against the nozzle and the inner ring got "sucked" into the nozzle a bit. I don't know how the inner cavity came to be. Maybe after the lip was formed, filament had to pass through a narrower hole (nozzle + lip) and the backpressure pushed against the weakened material above the lip, in the inner part of the teflon coupler. Wild speculations are wild!

Sorry for the delay. The finished product. It printed great. Prank successful

Waiting for Godot

That's exactly what I fear (I am not a native speaker and it gets in the way right now :/ )

In this image I simulate the case where the filament is loaded for the first time. If it is not perfectly straight it could hang on the inner lip in the teflon coupler, right before it enters the nozzle. I think I have seen it when I load filament. Shortly after the filament enters the teflon coupler, I hear a creaking sound and the filament jumps back a bit before it continues. This might be this scenario where it hangs a bit. However this is not the main problem. I imagine the main problem would be during printing and with retraction enabled. When the filament gets soft it might expand in the cavity at the exit of the teflon coupler. Through retraction this thick section moves up and down (already under pressure) and creates even more friction and resistance. Does this make sense?

Well the thing is, filament slides through it without problems. But if I move the filament sideways before it exits, then it hangs on the lip inside the coupler. I don't know if this could happen during printing because the filament is already soft and won't form a sharp edge.

Ok, guys, what do you think of the teflon coupler issue? Is it really a good idea to file away the lip? Chrisp, braddock - did you see any improvements after you did it?

How about they put one in every order they ship from their store. These sticker do not cost that much and the benefit of spreading them around is far greater than the cost. There is a reason why Apple includes their stickers with every product...

Well then count me in to the second group. My longest print didn't even surpass 5 hours. And when I think at illuminarti's monster prints - his extruder must fall appart already

But how could some of this issues be relevant only for some users? Are not all UM2 extruders alike?

Is this possible on YM right now? Last time I checked there were no collaboration features.

Ok, many thanks. I think I had the issue with the screw (top left) crashing down and thus pushing the spring down. But all in all, doesn't this only affect the enclosure when there is no filament inserted? Because, with filament, the ball bearing would push against it, and not the case.

And... you don't want to share your findings? Maybe, it'l help to understand my problem or to rule it out. thx

@gr5: Did I said thank you already? So thanks for the weight test. Regarding your other comments - already using Pronterface This was my goto tool for our crappy Pursa Mendel. Now I've got almost all ingredients here. Hypodermic needles, acurate temperature sensor, acetone (the nozzle is taking a bath in it right now). I've only missed those stupid bungee ties and here in Germany the shops are already closed. I will reproduce the weight test tomorrow. @AaronAlai: About the lip inside the teflon coupler. I am not sure any more if it is a good idea to file it away. Because if I do, it would increase the available space right where the coupler and the nozzle meet. If retraction occurs and the plastic is already soft, then it would have more room to expand sideways and on then hang on subsequent retraction action. @Chrisp: Quoting is alright for me (Chrome, Mac OSX). By the way, are you sure the extruder case is made of ABS? The finish and sturdyness feels more like those Delrin pieces from the UM1. @IRobertl: Just wanted to remind you that your new filament spool holder looks nice. I whish I had one like it. But I don't. So sad... @Ian: Where, how do you know about the extruder improvements? Is this another moderator insider thingie? Then I'd whish I'd be part of this Freemasonry underground movement

Looking at your cubes with the warped top surface, you should increase the top/bottom thickness to 1.2mm I noticed you print at "Bottom/Top thickness: 0.6mm". The initial discarge is ment to prime the head for printing and fill it up with plastic. Sadly there is no foolproof method to get the strands out of the way. When I start a print, I wait for the printer to start discharging filament, then quickly snag it off and hold it away from the nozzle until the bed plate has reached its final position and the head starts moving. If you grab filament strand midair, you can touch it with your fingeres without burning yourself. But be careful!

Sorry for the delay. I don't have time right now (working... this hobby of mine ), but I didn't assemble the head yet. I will also try to reproduce your extruder weight test since it doesen't compare with mine and the difference in "power" might result thereof.

WAAAAAANT!!!

Damn, I didn't - why? Does Ultimaker not want me to give out cool stickers to my friends? @Ian: I have a white car too, I feel your pain...

Alright guys, I took the head apart. This time right down to the bone, you know, nozzle in hand and all. I am pretty sure the nozzle is not blocked. Everything looks smooth right down to the nozzle tip. The teflon coupler looks fine too. I can slide filament without resistance. But there is a slight lip at the end where it sits on the nozzle: So if I insert filament and push it sideways a bit, when I move it through, it cants/hangs a bit on its way out. Also the area where the teflon piece and the nozzle make contact is dark. Is some sort of coating or just some burnt stuff that got in there? Next thing I found, the temperature sensor was covered in some gunk. Again it looks like something that got in there and burnt up completely. It fell off when I took it out of the heating block, and only a bit remained on the temp sensor: And speaking of the sensor. It looks like a little piece is missing. It is not the mark from the screw that holds both the heating cartridge and temp sensor in place. Just a little pice is gone (or is this intended? I have no idea how the sensor works. I hope I am playing captain obvious, pointing out something that every temp. sensor has) I think I need to file the lip away from the exit of the teflon coupler. I am not convinced that it is the cause for my problems though, because even with no retraction, my tests fail early and the filament is not moved back where it could hang on that lip.

Thanks for the tip. I think most tests were performed at 230° or higher, so given differences in filament, at these high temps, the effects should be negligible. That said, when I printed the extrusion test (no retraction) at 250° it failed only at 10mm^3/s. Don't know what I should make of it though. The temperature is pretty high and on the far end of what PLA can take.

Hi Tom, there are many ways to improve a print but in my opinon it boils down to these four points: Model structure and orientation As with any FDM printer, the inability to print mid-air restricts the model structure. This is one of the topics where you can expect most creativity from model creatores when they come up with ways to orient and support parts of a model in such a way that they will be able to print properly. [*]Speed Printing slow (20-30mm/s) will improve print quality but will obviously increase printing time. [*]Temperature A higher temperature will increase filament viscosity a so you will be able to print faster. [*]Layer height This is the most important parameter. A bigger layer height (0.2mm) for example will print faster but produce a more coarse surface. Printing below 0.1 layer height is usually not necessare because it takes ages and the visible improvement is minimal. The key combination is between layer height, speed and temperature. Sadly there are very few common rules to follow because every model is different. But that's the beauty of a rapid prototyping machine. Before you commit to a 15hr print, you could scale it down in Cura and print it in one hour or less to test for potential problems. Another thing to take care is the volume of filament you are asking the extruder to push through the hot-end and the nozzle. The Ultimaker Original and Ultimaker 2 have a nozzle with a 0.4mm diameter. In combination with layer height and speed you'd get this simple formula: nozzle_diameter x layer_height x speed For example: 0.4 x 0.2 x 150 = 12mm^3/s filament. There are certain upper limits of what the printer is capable of. As a rule of thumb (I hope others will correct me if I am wrong), when you want to print something with a high visual quailty - print at 20-30mm/s with 0.1 layer height and 220° temperature (for PLA). Also I suggest to enable the "full settings" in Cura and also open the expert settings. Usually one big question (depending on the object you are printing) is if you print with or without retraction and cooling enabled. Cooling will be helpful for small and thin features of an object where the hot nozzle would move often above the same part of the object thus not giving the plastic enough time to cool and harden a bit. Retraction is very helpful for bowden type printers where the stepper that moves the filament is not attached to the head. This allows for fast movement of the head at the cost of oozing plastic when the head travels to a new part of the object. Retraction is used to counter oozing and is often one of the factors that make a print look awful or briliant. There are many more future of Cura to look at and overall things you'll learn from experience. I don't think it is possible to sum all of them up here. Interestingly, that was my first and biggest gripe with 3D printing when I started. How do you know which combinations produce great prints? My idea was to create a kind of a cheat sheed for 3d printing (geared towards the Ultimaker) to help people understand basic concepts. I am not very far with this project due to lack of time, but it is still on my agenda and I am actively collecting random bits of useful information from the forums and elsewhere. So in the end I suggest you print lots of objects. If you print at 0.2 layer height and without infill they'll finish pretty quickly. Also make sure in Cura always activate "Layers" view mode (buttom top right) and move the dial (lower right) up and down to get a preview of every layer. There you can spot many problems before printing (like top covers that are too large to be printed without infill).

Ok, thanks for the tip. Since we seem to have the same problem, you could also follow my task list. Maybe something helps: mark the knurled bolt and motor rod to see if it slips during printing connect the UM2 to see if it gets temperature readings in other tools provision a temperature probe and compare the temperature of the nozzle take the head apart and check if filament passes through the teflon coupler freely put the filament on the stock spool holder do the extruder weight/force test use wd40 oil and spray a little in the bowden tube

Sadly I don't have anything here to clean the nozzle. I ordered 0.3 (30G) hypodermic needles but they didn't arrive... I will take the head apart to check the teflon/nylon part. Is there a way to completely take the nozzle off? There is one last screw which is obscured by the heater block. Or do I just need to unscrew the nozzle?