Almost always missing layers / underextruding

[Nicolinux 288]

True, but if you could test it and it turned out to be the solution we then know what is going on and focus on how to solve it.

As of right now we are still guessing for what the problem is.

Hopefully your todo list will shine some more light on it.

(I don't think it is temperature related).

 

Ok, then I will get some WD40. But wait a second. Is this the stuff we are talking about? (link)

If yes, as I am from Europe, like you - how would I get it? I am sure there are other brands and WD40 is just a famous brand name that is used as a synonym.

 

[Nicolinux 288]

To me the problem could still be many things grouped into 3 categories, problems with extruder, problems with nozzle, other friction (bowden tube, kinking, spool).

I'm leaning towards problems with nozzle (such as burnt, black PLA coating the inside), but I haven't ruled out the extruder yet. You could do a definitive test to rule out the extruder. Put a short length of PLA in the extruder and with the servo powered up pull on the PLA until the servo slips or the PLA slips. Pull by using weights. When done measure the weights. If you do this test I will duplicate it on my machine.

You could even repeat the test with the filament 90% through the bowden if you want to see if that makes any difference (I doubt it).

 

Ok, I will perform this test too. Getting desperate here - the UM2, my favorite toy is broken and I am sad and lonely so I need it asap!

 

[Nicolinux 288]

As a reference and as a complete 3d printer newbie (even if I have read the entire 13 pages, just for my personal knowledge) : Third print ever on my UM2 received this week

(UM PLA blue, 230°C, 50°C bed, filament on the stock reel holder)

 

Almost perfect... just so anyone lurking here could see these printers could definitely be good almost out of the box.

 

I'd repeat the test with the "retraction" version. I think this test is more of something you'd print often. I find prints without retraction unusual, but then again, it depends on what kind of objects you are printing.

 

[aaronalai 2]

As a reference and as a complete 3d printer newbie (even if I have read the entire 13 pages, just for my personal knowledge) : Third print ever on my UM2 received this week

(UM PLA blue, 230°C, 50°C bed, filament on the stock reel holder)

 

Almost perfect... just so anyone lurking here could see these printers could definitely be good almost out of the box.

 

Thanks for the post! As someone who is still waiting for their printer, I really appreciate it.

Also, Nicolinux you could probably get away with any type of light oil, like a light sewing machine oil. Although, perhaps SandervG suggested WD-40 because it is in a spray can with a long nozzle.

 

[IRobertI 520]

Test 2. This time I did the straight filament test. I straightened the filament as well as I could to about a 2-3m diameter circle and put the printer at the edge of the table, all other factors were identical.

These prints were done one at a time. On the left one I heard 3 skips in fairly quick succession right at the failure point, didn't hear any skips for the rest of the print. On the right one I wasn't around for the failure but I think I heard one skip from the next room. I returned to watch it finish the 9-10 segments and heard a single skip at the very last layer. But you can see a couple of layers of underextrusion still.

 

[Nicolinux 288]

As much as it sucks, but you might redo the test with filament in hand. Or at least for the last two segments to see if there is a difference.

 

[IRobertI 520]

On the right print the filament was suspended in air, absolutely zero resistance. Well, not counting a few grams of weight.

 

[SandervG 1,521]

Ok, then I will get some WD40. But wait a second. Is this the stuff we are talking about? (link)

If yes, as I am from Europe, like you - how would I get it? I am sure there are other brands and WD40 is just a famous brand name that is used as a synonym.

 

For example, this is a dutch link

I am sure you have them for each country.

I tried sewing machine oil as well, but that DID affect adhesion, especially on the bed.

With WD-40 I did not have this effect, besides deduction from friction it didn't have any side-effects, which is what you want. Also, I must add; a small spray is easier to dose then a squirt of oil.

 

Hey Sander, I had considered lubing the tube with inox (similar to WD40) but was worried about a few things... burn off smell, whether or not it would affect layer adhesion etc, but also, if it would casue the feeder to have trouble gripping the material, as innevitably, the lube will end up transfering back to the feeder also.

 

When I used sewing machine oil, it created a bit of smoke at first and later I really had trouble with adhesion to the bed.

WD-40 didn't give me these results.

Maybe these are not facts, but they are my experience.

 

[Nicolinux 288]

Alright bought this one (http://www.ebay.de/itm/WD-40-1-x-400ml-Spraydose-WD40-Kriechol-WD-40-Rostloser-/370890842425).

 

[SandervG 1,521]

Looks like the one I have at home.

 

[gr5 2,167]

Twice now people have reported that the little white teflon piece just above the nozzle was restricting the filament and drilling this out to 3mm drastically helped their underextrusion. Here is the latest from user mnis:

http://umforum.ultimaker.com/index.php?/topic/4145-small-question-about-material-feeder/?p=34106

I am still very suspicious about nicolinux's extruder however.

Also nicolunix, I know you consider your UM2 to be broken but it *does* print - just at half the speed of mine. So you can use it to print parts - it's just going to take twice (3 times?) as long until this problem is figured out.

 

[chrisp 10]

Twice now people have reported that the little white teflon piece just above the nozzle was restricting the filament and drilling this out to 3mm drastically helped their underextrusion. Here is the latest from user mnis:

I knew I wasn't crazy.....

On that note, my under extrusion issues are still there when I use the PLA Orange & Blue from the Ultimaker store. I haven't been able to figure out the cause yet. I have been printing perfectly fine at every layer from 0.2 to .06 with this white PLA I got off of ebay.

 

[Nicolinux 288]

Maybe you should also perform the temperature test. If your sensor is off, it may print with the wrong temperature and the white filament could behave differently at lower temperatures.

 

[aaronalai 2]

For example, this is a dutch link

I am sure you have them for each country.

I tried sewing machine oil as well, but that DID affect adhesion, especially on the bed.

With WD-40 I did not have this effect, besides deduction from friction it didn't have any side-effects, which is what you want. Also, I must add; a small spray is easier to dose then a squirt of oil.

When I used sewing machine oil, it created a bit of smoke at first and later I really had trouble with adhesion to the bed.

WD-40 didn't give me these results.

Maybe these are not facts, but they are my experience.

 

Hmm, sorry to lead you astray. I read about others using sewing machine oil for flexible filaments on the UM1

 

[chrisp 10]

Maybe you should also perform the temperature test. If your sensor is off, it may print with the wrong temperature and the white filament could behave differently at lower temperatures.

It's worth a shot. I think that my temperature sensor in my meter would be more accurate than the water test, but I can try both.

 

[chrisp 10]

I was going to post here about another clog that I recently had with the cheap filament I've been bragging about, but after further investigation, this is what I found.

 

It's hard to see in the pic, but the filament has a huge bulge that is well beyond 3mm, which stopped the filament from entering the Bowden tube where the extruder is located.

 

now I feel like I need to roll out the rest of the roll to check it.

 

[gr5 2,167]

Take a piece of sheet metal and drill a 3mm hole in it. Then run your entire roll of filament through the hole to test it.

Then throw it all away and get some filament from printbl.com

 

[Nicolinux 288]

To me the problem could still be many things grouped into 3 categories, problems with extruder, problems with nozzle, other friction (bowden tube, kinking, spool).

I'm leaning towards problems with nozzle (such as burnt, black PLA coating the inside), but I haven't ruled out the extruder yet. You could do a definitive test to rule out the extruder. Put a short length of PLA in the extruder and with the servo powered up pull on the PLA until the servo slips or the PLA slips. Pull by using weights. When done measure the weights. If you do this test I will duplicate it on my machine.

You could even repeat the test with the filament 90% through the bowden if you want to see if that makes any difference (I doubt it).

 

Ok, I performed the test. Had some trouble sticking filament to something where I could add weights to, but finally found a solution:

 

The blue plastic basket was an addon to my clotheshorse (german: Wäscheständer). In order to tie the filament to it, I guided the filament a few times around the basket handhold. Then I used my barbell disks to add weight.

 

The extruder on the UM2 can hold at least 8.75kg (19.3 pounds). When moving the extruder (used the menu option maintenance->advanced->move filament), it can move at least 3.75kg (8.3 pounds) and definitelly slips at 5kg (11 pounds). It slipped after I added another 1.25kg (2.75 pounds) disk to the 3.75kg in the basket (and moved filament).

 

I think we can rule out the extruder as the source of the problem here. Pulling with 8 pounds is enough to move filament from the stock spool holder for sure.

 

[illuminarti 18]

Interesting test, but not sure exactly what it proves... I don't think that you can conclude 'the extruder isn't the source of the problem'.. It's going to depend on what speed and how consistently the 'move filament' option operates.

Ideally, you'd test it during a print or at least while extruding at a known speed - if it takes 8 pounds of force to extrude at highish speeds, then any additional resistance will be enough to tip it over the edge.

[gr5 2,167]

I'm very glad you did this test. Can you post this same post in a thread by itself? I'll post my results in the same thread. I am printing something right now but it should be done in a few hours. I will do the same test.

@illuminarti - I think this says a lot - I believe the feeder has the same torque when stopped as when moving (or slightly higher than when moving).

nicolinux - I think you should concentrate on your nozzle. Do you have acupuncture or hyperdermic needles or .3mm drill bits or something strong and metal that you can use to clean out the tip of the nozzle slightly? Just rub it around the inside of the nozzle hole 5 or 10 times trying to scrape out any possible gunk that is stuck to the side of the nozzle hole. Don't push it high enough up such that you damage the nylon (it's pretty far though so it should be safe).

Also I think you should check the white nylon piece to make sure the filament slips through it easily.

 

[Nicolinux 288]

I will post it in a new thread, but I think illuminarti is also right. Maybe we need something more scientific than "add some weights and turn the knob to move filament a few notches".

For my purposes though - to find out if my extruder is weaker than gr5's, it should suffice. But to make it comparable with other UM2's I would need to connect via an external tool and set it to extrude constantly at slow speed. Because the total length is limited in two areas. For one I don't want the filament to reach the head/nozzle because this will add additional pressure. And second, the filament shouldn't extrude too much because then the basket with the weights would hit the extruder. Ideally it should extrude a bit then wait for a few seconds so I can add snother barbell disk and then extrude again.

Now, how would such a gcode snippet look like?

 

[Nicolinux 288]

nicolinux - I think you should concentrate on your nozzle. Do you have acupuncture or hyperdermic needles or .3mm drill bits or something strong and metal that you can use to clean out the tip of the nozzle slightly? Just rub it around the inside of the nozzle hole 5 or 10 times trying to scrape out any possible gunk that is stuck to the side of the nozzle hole. Don't push it high enough up such that you damage the nylon (it's pretty far though so it should be safe).

Also I think you should check the white nylon piece to make sure the filament slips through it easily.

 

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?

 

[chrisp 10]

Nicolinux

You just unscrew the milled fitting, then slide the nozzle and heating element out together. The screw directly behind the milled fitting is only a guide, it's not screwed into anything.

Even after opening up my Teflon fitting, my printer worked good for about 1.5 weeks and now it's back to unexplained under extrusion. I am really loosing my sense of patience with this machine. I just completed a 25 hour print that needed to be watched almost the entire time with the end result being as less than desired print. I used the translucent blue from the Ultimaker store.

[Nicolinux 288]

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
   
  

 

[yellowshark 153]

Hi guys, this is a great thread which I have been following avidly. This is certainly not at the hub of the matter and I do not want to teach anyone to suck eggs but also do not forget that any different filament from the same supplier may well need different settings.

Today I tried Faberdashery’s Pearly white PLA for the first time. I set up with my standard test settings which are 300 microns at 60 m/s and 210 degrees. This is what I use for most of my Faberdashery filaments in test mode, including their Arctic white. What a mess, major under extrusion. After several attempts I loaded my benchmark Colourfabb Dutch orange to make sure there was nothing wrong with the printer – that worked fine. In the end I had to run at 230 degrees to cope with temp. variation; dip a degree under 225/6 and it would under extrude.

So two whites from the same reputable supplier and 20 degrees difference in temperature.