The original Bowden tube from Ultimaker is made out of PFA which is transparent. PTFE is usually milky white (means the filament is much less visible, neither any dirt inside the tube).
For Swiss users there is another source for 1/4"-1/8" PFA Bowden tubes now but I cannot give any details here as I would get in conflict with the forum house rules. 
I'm pretty sure that with new rods it will be perfect as the others.
I upgraded one of my UM2 with the upgrade kit and replaced the rods on my 2 years old UM2 and only that changed the print quality a lot (i also changed the block and temp sensor + new 35w heater and took the newest UM2 head i changed with the upgrade kit). Maybe the LMUU6 bearings from the head can add some friction also.
The feeder (Roberts) and tube are still the standard ones.
i actually replaced all of the bearings, including the LMUU6 bearings, to get rid of some noise.. did it on the one, not the other, so that;s not it...
I've been having the same issue, but this is on a factory UM2+ and not an upgrade. I can print the same part on my UM2 without issue. I have just done a test where I slowed the speed right down (way below the recommended speed for the material) and increased the temp. This did reduce the issue by a far margin, but still not perfect. I have taken apart the feeder and everything is fine in there, so I'm thinking whether this might be a temperature issue. Whether its indicated temperature isn't correct or there is some other issue. I have tried all other suggestions as above to try and fix the issue, it has even been back to UMUK to have a look at.
BR
Rich
So let's wait for the new rods
I've been having the same issue, but this is on a factory UM2+ and not an upgrade. I can print the same part on my UM2 without issue. I have just done a test where I slowed the speed right down (way below the recommended speed for the material) and increased the temp. This did reduce the issue by a far margin, but still not perfect. I have taken apart the feeder and everything is fine in there, so I'm thinking whether this might be a temperature issue. Whether its indicated temperature isn't correct or there is some other issue. I have tried all other suggestions as above to try and fix the issue, it has even been back to UMUK to have a look at.
BR
Rich
please note that your UM2+ will need about 10 degrees of a higher temp than your UM2.
I would recommend print the same thing but now with 10 to even 15 degrees higher on the UM2+. this should give you an identical result.
also, there seems to be a bit of play on the inside of the feeder with the arm that supports the feeder bearing. this can cause the guide bearing to shift, pushing the filament towards the non-curled portion of the feeder. opening up the feeder, cleaning it and rebuilding it should solve this but first I would reocmmend adding 10 to1 5 degrees to the temp.
Well if your source would be shared from an informative nature over a solely promotional nature I would tolerate itThe original Bowden tube from Ultimaker is made out of PFA which is transparent. PTFE is usually milky white (means the filament is much less visible, neither any dirt inside the tube).
For Swiss users there is another source for 1/4"-1/8" PFA Bowden tubes now but I cannot give any details here as I would get in conflict with the forum house rules.
2
The teflon isolator was mounted with too much pressure on it.If that's the problem try loosening the 4 thumb screws on the heat a turn and the problem might go away.
Wasn't that fixed? I remember that @sandervg said something about the new hotend assembly had some kind of internal spacer to remove that assembly errors on um2+.
I think you and @gr5 are talking about two different things. What you mean is that our production facility is using a spacer to determine and check the space between the PTFE coupler and the bottom aluminum part.
What George means is indeed the aluminum spacer that replaces the spring. Which is also true, obviously.
When you disassemble your printhead you may install it back with a slightly different positioning of the ptfe coupler. I asked like 2 weeks ago if that (first) spacer could be shared, let me follow up on where that request stands. I remember some feedback was that if this would be 3D printed the exact measurement could not be guaranteed, since it also depends on your slicing profile and calibration but it would certainly be a good guideline.
In case of this issue, @Korneel, did new rods change anything? Do you have them already?
Since you use custom parts, what did you replace with original parts? Which didn't you replace and which with custom parts? Could it be the bearings perhaps? If they were all updated with (most of an) extrusion upgrade, and age has a role it must be in one of the parts which are not replaced and are part of the motions.
1
my apologies for the super late reply;
so here is what I did over the past few months;
replaced the TFM again. check
verified the smoothness of the filament channel. check
cleaned the feeder (um2+ feeder). check
change the rods. check
change the nozzle. check.
change the rods. check.
change the belts. check
change the bearings. check.
change the firmware. check.
change the flow rate. this was interesting, but while it offered some improvement, this was impossible to get consistent.
changed the electronics board. check
so i have now changed everything about the printer.. the problem is still there...
in a half-drunken let's buy-shit mood, i bought a bondtech extruder. i installed this over the weekend.. guess what. problem gone. as in. completely gone. i printed something with the original feeder, very obvious walls not touching and lines not touching in the layer. after the bondtech feeder, all is gone and it does not have the signs of over extrusion..
1
and after a couple of days of 24/7 printing and testing i am now happy this has recolved my issues.. i've even bought another 2 bondtech extruders..
and after a couple of days of 24/7 printing and testing i am now happy this has recolved my issues.. i've even bought another 2 bondtech extruders..
Just for the shake of curiosity. Would you mind on taking 2-3 atomic pulls and measure the dia of the pulls? (And photos please)
and after a couple of days of 24/7 printing and testing i am now happy this has recolved my issues.. i've even bought another 2 bondtech extruders..
Just for the shake of curiosity. Would you mind on taking 2-3 atomic pulls and measure the dia of the pulls? (And photos please)
you're thinking the inside of the coupler has collapsed? no it hasn't.. I am using TFM couplers, in the process i actually replaced them. I can add the picture if you want but it's 2.85 all the way up to the nozzle.. there is no widening or any other collapsing or whatever of the coupler. I also replaced the couplers with brand new ones, and i immediately had the error..
and it's on all 3 machines..
but what are you thinking?
ps: when i do an atomic pull it comes out almost brand clean..
I had 2 TFM that did collapse upon installing them. One I fixed it with a 2mm drill bit (mines are for 1.75) and the second tilted, probably because when assembling all, the screw that goes from the block to the aluminium can touch the fan alu heat sink shifting the angle of the olsson. The best way to check them (IMO) it's to make them spin on a piece of filament. They wooble badly when something's wrong.
Edited by GuestI had 2 TFM that did collapse upon installing them. One I fixed it with a 2mm drill bit (mines are for 1.75) and the second tilted, probably because when assembling all, the screw that goes from the block to the aluminium can touch the fan alu heat sink shifting the angle of the olsson. The best way to check them (IMO) it's to make them spin on a piece of filament. They wooble badly when something's wrong.
great point 
what I felt was a good way is to unscrew the nozzle, take out the bowden tube, then gently feed some filament that passed through the feeder and feel for resistance.
in all of my printers, it goes through supergently so that's not the problem..
I totally agree with your assumptions, unforunately, i went through all of these :(
no it was really the feeder for me..
the interesting thing though is that i had the problem in all 3 printers, and the oldest one had it worst..
i absolutely think it's an addition of issues..
if you have one of the issues, you would not notice anything.. everything I did absolutely improved quality.. however, changing the feeder made the biggest improvement..
1
Do you have replaced the bowden tube ever before?
Is it possible that this was the most important point...?
Do you have replaced the bowden tube ever before?
Is it possible that this was the most important point...?
yes I did
sorry, was not in the list.. but replaced this with an original one and with one from 3dsolex...
I have also just installed a Bondtech feeder onto my UM2 and the difference is night and day. Its an amazing bit of kit and has transformed my UM2. Will probably get one for my UM2+ as well now. I was having major problems with over extruding and oozing of XT-CF20 filament, but with identical settings as before that issue has completely gone now. There isn't even a small bit of material build-up on he nozzle.
These feeders are certainly worth their money and they are not that expensive either.
BR
Rich
1
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Hmm, I just read through some old threads about PFA vs. PTFE bowden. Ultimaker seems to use a 1/4" outer diameter and 1/8" inner diameter tube which is roughly 6,4mm and 3,2mm. The PTFE i bought is 6mm/4mm. No problem so far, but the imperial size seems better to me. There are a few european shops who sell those imperial ptfe tubes too, but far less than 6mm/4mm and most in large quantities only. The german shop www.2printbeta.de seems to sells short lengths. Never heard of them. It certainly is much easier to find imperial tubes in the US.
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