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Both of our UM2's have extreme under extrusion issues

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Hey guys, I work at a Media Center at my University and we have 2 UM2's, both have extreme under extrusion, I've been working with them for about a year now and have done as much research on the forums as I can but can't seem to find the root cause for our under extrusion, it seems to change on a daily basis. Sometimes it prints great, sometimes it's horrible.

Things I have done:

  • Atomic method / cleaned nozzle, looks perfect.
  • Adjusted the spring on the feeder at the back (It's at the top but have experimented with other placements with no effect, or worse)
  • Adjusted printing settings several times based on recommendations on the forums
  • Leveled build plate
  • Changed / tried different color filament
  • Oiled up the machine
  • Updated firmware/Cura

 

Other Observations and Notes

  • Material stops coming out completely when machine retracts for about a full second (causing huge gaps in the prints)
  • The material tends to "curl upwards" when it initially starts coming out and grabs on to the nozzle, sometimes i have to use a piece of PLA to get it off the nozzle.
  • EVERY time I abort a print I have to remove the bowden tube and cut the end of the PLA off as it gets thin at the end and can't push through the nozzle
  • Has only ever used PLA (Specifically from UM), never ABS

 

As these printers are for University use they both get extreme use (roughly 72 hours a week), I wonder if maybe they are just being used far too much and we're wearing them down really quickly. We've had the print head on our original UM2 which we got around September 2014 changed and it's working fairly good, it has problems right now but I suspect it's just due for some basic maintenance.

Our new one is experiencing extreme under extrusion though, the only way I can solve it is by cranking the temperature to 250 or above. Anything lower has extreme under extrusion. I only printed this high for testing the Ultimaker Robot print, it usually runs at 210-225 max. I'll give you the printer settings and cura screen shots, but the files we put on the SD cards are handled by multiple people on multiple machines so I can't guarantee everyone's settings are the same (Perhaps we should ensure we all use a default go to setting for average prints and only change upon need).

I've suspected it could be the Teflon insulator, but the machine is fairly new, how long do these usually last before needing to be replaced?

Here are my cura settings

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Here are some prints - For the robot on the left I adjusted the printer up to 225 (from 210) and that's the result. The one on the right (which is still not as good as I'd like) was tested at 250, which is way too hot to be running for PLA let alone for 72 hours a week.

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This was also printed at 225 and came out horrible no matter how many tries and adjustments made.

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And here is one that printed about a month ago with the exact same settings which looks pretty decent for a low-normal quality print. We don't use high quality settings as it's for students to use and if we made every print high quality it would take forever for students to get their prints.

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Any and all help is appreciated!

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PrintScreen2.thumb.png.85c4655d3cd2868db8b41b6bdb92dcb1.png

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Wow - a lot of information.

It's unclear to me if it was doing this from the start or if something changed. If it used to print better then the most likely things are the nozzle and the teflon part. Did you try changing the teflon part yet?

The curling filament as it comes out of the nozzle is normal if a 100mm strand is heavy enough to get it to fall straight. If you have a hanging 100mm strand and extrude a little more and it curls up then your nozzle needs cleaning - preferably with a piece of metal smaller than .4mm like a syringe or acupuncture needle or maybe the steel wire from a wire brush such as those used to comb dogs or clean bar-b-que grills.

If you really want to print faster there's some great advice here - you can get 4x improvements:

https://ultimaker.com/en/community/18451-how-can-i-speed-up-my-prints-a-little

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Hey, thanks for the reply, I should have mentioned I've cleaned using the atomic method and also on the other end of the nozzle using a needle, it tends to to curl up no matter what, but I'll give it another try with cleaning.

And no I haven't tried changing the Teflon yet (we'd have to order a new one) but I'm more curious generally how long these last (in hours preferably) so we can look into ordering multiples at one time for future replacements, is it safe to assume 1000+ hours is a lot? I'm not sure how many hours the UM2 usually gets in a household setting compared to ours, but it's more or less running the entire day 7 days a week.

I'll post an update if anything changes!

Thanks

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1) You still didn't answer about if this is a new problem or since you got the printers. I'll number stuff so it's easier for you to keep track.

2) No one seems to have an exact number on how long teflon lasts. I've heard "500 hours" but I'm not sure what temp as it lasts *much* longer at 220C than at 240C.

3) I sell a higher temp teflon called "TFT" which you can print at 255C continuous for years no problem. I only sell to USA, Canada, Mexico but for people outside of North America go to 3dsolex.com (I'm a distributor for them). My website is http://gr5.org/store/. I have a reseller in canada at shop3d.ca but he doesn't sell the TFT parts - just ultimaker teflon. My store is at gr5.org/store/

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Oh - if you are going to buy from my store you might want to get an Olsson block while you are at it (shop3d.ca has those). That will let you change nozzles easily and if you want to print real fast you can print with a .8mm nozzle (4X faster). Only one wall pass needed to get .8mm walls instead of 2 passes and you can print .3mm thick layers if you are in a rush.

Also with the olsson block it's easier to diagnose if there is a problem with the TFT because you can remove the nozzle and push the PLA though the teflon while it's under pressure by the bowden and spring and feel the resistance.

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Thanks for the info I'll look into the teflon you mentioned, and it's not a new problem, we print quite well for a few hundred hours then it begins to go downhill. It happened last year with our old printer eventually and we ended up changing the head which solved most of our problems, but obviously we don't want to be changing the print heads often.

It's starting to happen again with both of our printers this year now. I'm guessing the underlying problem is that we are just pushing them too hard maybe, I don't think they were designed for 1500+ hours running constantly. I've tried just about every trick and tip in the forums and nothing seems to help other than raising the temperature above 240 which is definitely not ideal. My only other concern is maybe the spool is having a hard time being pulled by the feeder, right now its just on the back of the UM2 with the default spool holder, we have a few other printers around the campus and they area using a custom made spool holder that seems to have drastically improved their printing, we're currently getting some made for our own printers, I'll post an update if it improves!

Thanks!

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No sooner then a few minutes after I post do I manage to pull the Teflon piece out, I just used a small scraper for painting to get some leverage underneath and pop it out. Our suspicions were correct though! Completely burnt coupler! At least we know what the problem is now, luckily we actually had a spare one so I'm going to replace it now and get back with how it's printing, thanks for all the help, we're going to look into the Olson blocks and some of those couplers you linked earlier :)

Thanks again!

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Edited by Guest

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Awesome, printed a test Robot at 210 and it came out great, looks like the Teflon was our main problem, we ordered a few of those TFT Teflon parts to throw on our printers. Oh also I'm going to document the lifespan of this stock Ultimaker Teflon part I just replaced. I'm going to check it every 150 hours to see how far along it's gotten in terms of burning, we'll most likely print at just 210 but occasionally up to 225 so it should be an accurate take on how many hours you can get out of the stock ones at 210 regular printing with PLA. I'll make a new post to document the process once I've got it started.

Thanks for all the help!

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Edited by Guest
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