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Problems extruding

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Hi there,

I've been having some problems with my UM1. It works fine with prints up to 2 hours but when I try to print anything longer than that it either starts to underextrude and then it extrudes normally again or it alltogether stops extruding.

I've been trying to print a case for two weeks now with very poor results.

Up till now I've:

- cleaned the nozzle

- made sure that the screw at the back of extruder was tight but not too tight and that I have a constant flow of PLA

- switched the steppers with eachother (I thought the motors were overheating, it wasn't the case)

- cleaned the extruder, made sure there was no PLA reside on the screw inside the extruder or the plastic wheel that pushes the filament

- tried different PLA

- additionally, because of other problems I've had, I've made sure the belts are alligned and tightned.

Here are some pictures of parts I've been trying to print:

https://www.dropbox.com/s/mj8yx0mm375o5fs/DSCN7350.JPG

https://www.dropbox.com/s/yitmmqxbhw8fsx0/DSCN7351.JPG

https://www.dropbox.com/s/8lix1e4ou1ys492/DSCN7352.JPG

https://www.dropbox.com/s/j0gth8fu27ru13n/DSCN7353.JPG

I've run out of ideas. Has anyone had problems simillar to mine?

Thank you all,

ina

 

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I've had similar problems. There was random failure and nozzle clogging, starting relatively small but then reaching a point where I couldn't print anything at all anymore. At first I didn't find any cause, everything seemed fine.

In my case, the culprit was the nozzle temperature sensor's wiring (along the bowden), which was broken (slack joint).

If you have an Ulticontroller: observe your temperature readings (for at least 10 minutes continuously). If the nozzle temperature jumps from let's say 200°C to 205°C suddenly (anything more than 3°C at a time, after the heating-up period of course), then you probably have exactly that problem. The nozzle temperature shouldn't jump several degrees during normal operation, so if you actually see that, then you do most likely have that problem.

If you don't see any suden jumps in temperature reading - then ignore all the rest I'm going to write ;)

If the connection to the temp sensor is broken mid-print, then the reading will just remain at the last read value - resulting in uncontrolled heating or cooling down of the nozzle. At some point, the slack joint does make connection again and the actual temperature is read -> jumping from one value to another suddenly.

(This can be "simulated" by actually disconnecting the temp sensor wire on the UM electronics during mid-print)

The effects can be randomly clogged nozzles, overheated material inside the nozzle, smoking nozzle up to the point where the printhead actually melts down.

 

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I've checked to see if it was a heat sensor problem, either then going above the set temperature with 4-5 degrees when I preheat it doesn't do more that fluctuate 1 degree above or under the set temperature at the beggining of the print.

I'll be keeping an eye out for the temperature from now on and see if this changes.

What we've done after the temperature check was to clean out the nozzle with a drill. It's been printing well for four hours now...fingers crossed...I have a 17 hour print awaiting

 

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Dear all

I had big Problems with unreliability since I have UM1. (almost 2 years now.)

To make it short:

Finally I found out that the real temperature on the nozzle (measured with a separate Equipment at exactly the same place as the UM senosr) is far away and changing.

After studying the chip documents, how to measure with a thermocoule as used here, I found following solution:

Shield your sensor cables from sensor print until the sensor itself, Ground it at the sensor board. (soldering to the -pin).

Position the sensor board verticall in the air, so both sides have the same temperature. (because the IC measures the cold junction temperatures of the Connection Pins to the sensor, but they are opposite of the chip. This temperture error goes directly into the differnce)

With this changes, I am now always within 1°C

Your Firmware works perfect, the heater now cycles very constant wtih the same PWM all the time.

Now printing seems ok.

If you tell me how, I will send you a Picture.

Best regards

Franz

 

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The thermocouple sensors are shielded in "newer revisions".

At least I always got shielded sensors, ordered August 13 and January 14. There shouldn't be any problems with that.

I don't know if it makes sense to also use a shielded cable running along the bowden. I'm going to replace that cable with a high-flex one, and I have shielded high flex cabling around.

The standard cable shield doesn't connect to the amplifier board but only to the sensor head, but I guess that's the negative part of the thermocouple anyways.

Not sure if it's wise to put the thermocouple negative to GND, but I'd have to look a lot closer into the design to judge that. It seems to work well (as long as the cables are intact) so I didn't give it much thought.

/edit:

See: https://www.ultimaker.com/products/thermocouple-sensor

 

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Hi All

I seem to have the same issue as Ina described. My pictures of my prints look almost identical (sometimes, it appears random to me and is not that bad). I printed VERY well for the last year but now it slowly starts to degrade.

All of a sudden, like last week, i got the MAX_TEMP... ERROR and I was able to trace it back to the thermocouple cable going from the amplifier board to the UM electronics board (slack Joint). So I just simply replaced it with the "spare" cable. But the Problems are not gone... probably still a slack Joint somewhere?

I will Monitor the Temperatur as Jonny suggests and also, just to be sure, clean the nozzle (everything else I have done in the meantime, belts, screws, extrudes the right amount etc.)

Ina, were you able to fix the Problem with drilling out the nozzle? In my case I think it might also be a nozzle issue, I seem to remember that I printed with laywood before it started to get worse...

Best Regards

Martin

UPDATE: Currently printing with octoprint. Temperature is extremly stable...

UPDATE2: Just tried to clean the nozzle and restartet a 5 h print. let's see.

 

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Dear All

printing is back to normal for me. Quality is great again on my UM1.

The nozzle cleaning process worked (one of my spare resistors saved me, the leads were exactly 0.4 in diameter)!

thanks and happy printing,

Martin

UPDATE : NOT REALLY, after one sucessfull print, back to the same Problem. Will probably be required to replace the nozzle?!

I am out of options... any ideas? My prints look exatcly like the ones ina posted. Sometimes better (even great) and then again totaly messed up.

UM1 extrusion issue #1UM1 extrusion issue #22014 05 03 00.00.082014 05 03 00.00.162014 05 03 00.00.122014 05 03 00.00.192014 05 03 00.00.262014 05 03 00.00.23carved out Hot End Isolator Coupler

 

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Dear All

I cleaned everything again, changed filament, again. At least (without retraction) I was able to print 3 pieces (rather long prints). While cleaning and taking everything appart I found that when I load filament into the bowden tube, that when I push it until it reaches the hot end isolator coupler, there is a small, but notable, hickup. it's like a small step. All components still look ok, at least visualy, not compressed, damaged or anything.

So I re-assembled, printed and hmmmm... strange things happening. The underextrusion is only happening (mostly) at the back of the print (looking from the front of the UM). Like on the heads way back it sort of compresses the bowden tube and that then ist enough to stall the flow? See the pictures attached:

2014 05 03 00.00.26

2014 05 03 00.00.23

2014 05 03 00.00.16

 

Anybody had that before?

 

Thanks and I wish you all a great weekend!

 

Martin

 

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The only thing I ever had which might be somehow related to your issue was the effect of having a rougher surface at the lee side of the print due to small irregularities of the line thickness.

Can you please give some more information about print settings? It would be nice to know at which speed, at what temperature and with what kind of material (including brand) you're printing.

 

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Thank you Dim3nsioneer for answering. (so many swiss I realise)

Various different Settings, and different Filament from different manufacturers. All PLA, the White you see is from Swiss RepRap (or german). The blue (translucent) and red are from Ultimaker (but same effects).

I printed with 0.1 layer height, 0.8 Shell and 0.8 bottom and top thickness. Print Speed was 50 mm/s (retraction 0, as I thought it might not help in my case). Temp was 210. Flow 100%, 2.85 Filament.

My plan:

- replace the bowden tube + the cupler (maybe also the nozzle) and see if that changes anything, what do you think?

 

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Your print settings are indeed very reasonable (I use the identical ones). ;)

Does the filament slide well inside the Bowden tube? Maybe try it with the print head at different positions. You may also check if there is a very fine strand inside the Bowden tube. Such a strand could block a proper filament feed.

I assume you made sure that the feeder screw is well adjusted and the teethmarks in the filament look as they should.

If you have a spare Bowden around, feel free to exchange it but I would not especially buy one until you're sure it's coming from the Bowden (e.g. if you see a buckle in the Bowden tube). The same goes for the nozzle. Just check (with a magnifying glass) if it looks ok or if it might be damaged.

About the filament diameter: Is 2.85mm the value you actually measured or the value specified in Cura? If you haven't measured the diameter yet you should do it. I guess 2.85mm is quite ok for Ultimaker PLA but I would double check for Swiss / German RepRap filament.

 

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Good Settings then :cool: !

Great suggestion with moving the printhead while inserting Filament, will try later tonight or tomorrow and Report back.

I measured the Filament both are ok. (between 2.82 and 2.92). I Need to say I never had issues before and I still use the same spools as previously.Feeder screw is ok (I also tested various Settings there).

 

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ok. I tried a few things.

First, I removed the bowden tube for visual inspection. It's hard to say but I think she's ok. Not day 1 but ok. I feel nevertheless a slight friction at points when I load Filament (but this could be the curled Filament, right?).

But I can for sure feel the part where the filament leaves the bowden tube and enters the white coupler. Can you?

I also printed again, I do not think it's the nozzle. I printed a small Robot even with retraction on (4,5 just to test) and it printed fine, even great.

Then I started a bigger print and I had to stop after 30 sec because the Extrusion stopped and bowden tube started to lift from the feeder side.

Could be that retracting makes it worse because it gives it even more chance to hang at that slight imperfection in the tube / coupler once the filament is "warm"?

In Addition I guess when the head moves backward the bowden is pressed forward slightly, that would also add to the friction and be enough to stop extrusion? I tried to simulate extruding by it hand / ulticontroler but could not reproduce it.

Interesting, no! I will keep on printing and see if I can find out more..

 

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The Bowden tube must not slip at all. Do you have a Bowden clip at the feeder's end? If not, print one ( there are various designs @ Thingiverse). If you already have the clip, then something is definitively wrong with the Bowden tube and/or coupler.

I also don't recall feeling the Teflon piece when inserting filament. You may have a small gap between Bowden tube and the Teflon piece.

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Thanks Dim3nsioneer.

I already use the clip. I was realy careful this time re-asembling the bowden tube, pressing it well into the teflon piece so I could avoid gaps.... did not really change anything.

With regards to the feeling of things, I think I slowly get paranoid while inserting filament probalby feeling every little hickup! :???: I never even payed attention to this before.... so I can not say if something changed / is different.

I also believe that it's either the bowden tube or the teflon coupler. I will ask the ultimaker-team to send replacements. I will report back on progress here.

 

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Short update. I could not print anymore so I decided to take it appart once more. Now, when you look at the teflon piece from the other side carefully and in broad daylight, you can actually see that in mine there is something like a carving!! How could that happen? Any of you had that before?

Attached the Picture of my Hot End Isolator Coupler (adjusted the contrast a bit so you can see better):

carved out Hot End Isolator Coupler

At least I think I found the issue.

Thank you for your help!

 

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I did buy this Printer as a kit and built it myself, that was my goal from the begining, otherwise, no much fun, right? :mrgreen: So I am sure this is not from pliers... it's also really round, would be hard to do with pliers.

The only thing I could imagine is that it all started more or less after a few prints with laywood. That maybe carved it out after it cooled and I took it out? Or maybe there is too much pressure from top so it was pressed together at the weakest Point and got scraped away?

You do not happen to have one of those laying around, have you?

 

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Maybe we didn't mean the same thing. I was referring to the vertical lines.

And no, I do not have a spare teflon piece... :blink: never had a problem with it. But I do very rarely change the filament.

 

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Oh... ok. Yeah, I see what you mean, sorry. Hmmm... I don't think so, I in try to avoid pliers on flex pieces (and in general). But I I now had to take it appart a few times but only since it's not printing anymore ... so it might be some "fight-marks" (Kampfspuren), if you know what I mean :mrgreen: . My printer was printing since over a year without issues and I did not even have a nozzle clogg or anything. The only thing was that I had loose pulley screws, missed steps (which was easy to fix). So I really have no clue where this comes from.

I have created a support ticket (open since 02.05.2014), maybe UM Support knows more on the subject. I will probably just buy a new one and keep on going. If they have a solution / root cause I will update this post.

 

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This teflon part is the reason why I'm trying to switch to another hotend design...

I've wrecked two of them up to this point. Disassembling the hotend when you have a clogged hotend (and mine kept clogging at the teflon part) always lead to damage on the teflon part for me.

It's a major design weakpoint imho.

Sadly I don't have any spare teflon parts either - trashed all of them except the one I'm printing with at the moment..

 

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Hi JonnyBischof, thanks! I was turning crazy thinking I am the only one with this issue. I currently have an order open with UM so I will try to add 1 or 2 to the order... want one? :-P

 

This teflon part is the reason why I'm trying to switch to another hotend design...

 

Direct drive? Which design (is this part of your UM Black Edition build, cool btw, I might borrow some ideas!)?

 

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