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somerwil

UM2 startup problem, questions and remarks

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Hi guys,

After I sold my Ultimaker Original I finally received my Ultimaker two days ago and started printing right away. It seems something is wrong with my machine and I have a few questions... Hope someone wants to help me out.

First my biggest concern.

The extrusion on the machine is not a constant flow. Some layers seem to be just fine while other have under extruded parts resulting in a not so nice finish of the shell but also a weak print due to bad layer adhesion.

I printed a full plate of the Bubblox brick by Gijs (https://www.youmagine.com/designs/bubblox). 15 brick turned out to fit the platform so I decided to give it a go. Cura decided to print these bricks one by one. Out of these 15, only 5 were printed OK, 5 had flaws but are usable and the other 5 kind of only looked like the wanted brick but I could easily break the part by hand. Some layers in these brick simply didn't print well since the extrusion seems to jam somewhere/ stop. I get the idea that the first bricks where better than the bricks the machine printed later on. The print took approx. 7 hours.

Next thing I did was to print another part and it started with bad extrusion on the fourth layer or so. I stopped the print when I saw it was not going well.

Also useful information to find a solution might be that I also had some problems with the extrusion part during the setup step of the machine. On the point where I should wait for the extrusion to come out of the head I waited and waited but no extrusion... The motor runs and the material loading process seems to be going OK but when the material should exit the nozzle the motor sort of skipped. I could see the material feeder bolt bouncing back after too much pressure was put on the PLA. Not knowing what to do at this point I decided to push the button and hoping to get the extrusion going later on. That magically turned out to work when starting a first print.

Last thing: So far I printed the yellow PLA of Ultimaker (with the problems described above) and some even older white PLA of Ultimaker. On that white print I can see no weird extrusion at all.

So far my biggest problem, help is needed!

Now a few questions:

 

  1. I noticed my X-axis timing belt on the motor side was pretty loose so I tightened is a bit. No problem but when doing that I nearly burned my fingers. The motor was really, really hot. I checked the Y motor also. It was a bit less warm but I couldn't get my fingers on it or more than three seconds. Is that normal? Is it likely my extrusion motor runs too hot resulting in bad extrusion?
  2. On my white print (the second print I did) I tried to make a square cube. It did print fine (no extrusion problems) but it isn't exactly 90 degrees. It seems a bit 'curved' when looking at the part from the front of the machine. Can this be caused by the X-motor belt being too loose? I tightened the belt to prevent this but perhaps something else is wrong here.
  3. I miss the temperature seting in Cura... How can the one of the most important figures be removed from the program? It's not even available from the expert settings anymore.
  4. What's the best way to fully clean the glass platform to get rid of the glue?
  5. When starting a new print it seems my extrusion gets going a little too late to print the first layer correctly. This may be caused by my extrusion problem but perhaps the startup gcode needs a larger value for the startup extrusion time.

Other than these things:

 

  1. I love the heated platform! Print can be easily removed and their bottom is straighter than ever before. Wonderful
  2. The setup of the machine is really easy. The steps are so clear even my mother can setup this unit! (without the extrusion problem that is ;-))
  3. The LCD screen is great. Menu system speaks for itself.

Thanks for reading!

Michael

 

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The temperature setting is totally handled on the printer now, so that it's removed from the Cura. Similarly, the filament diameter, and retraction speed and distance are set in the printer, not in Cura.

One thing to check... Is the 3rd fan on the back of your print head running all the time? It should come in as soon as you turn the printer on. Some folks had problems with the wiring of those out of the box, and that can cause print quality problems.

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This is a lot in one post. You might have to re-ask some of your questions and you might have to supply pictures to explain better.

1) very hot motors is normal

2) You need to show picture, sorry.

3) Go to the tune menu. Once you hit "print" you can immediately go to tune and change settings before it actually starts printing. After you exit tune menu it will start printing if up to temp. While printing you can go to tune menu and mess with other settings live (such as retraction distance! couldn't do that on a UM original!).

4) Water works fine. I usually use glass cleaner and a rag as glass cleaner evaporates faster.

5) If machine has been hot for a while I usually manually extrude before I start the print. It's buried in advance menus somewhere. "move material" maybe?

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Hello guys,

thank you very much or your quick reply! Sorry to ask so much in one post but there's an answer to most of my questions.

I started printing today and checked the 3rd fan and some other things. The 3rd fan is working correctly so no problem with that.

To try to solve my extrusion problem I switched back to the white PLA again since that color didn't give me troubles so far. When printing the same gcode is also had problems with the extrusion now... It might be that it doesn't really like 0,3mm layer thickness. With the tips as described above, I went through the "Tune" menu and found the temperature settings. Bringing the temperature up (from 220 to 240 degrees) my extrusion problem is now gone! The machine is working extruding fine now. Very happy with that.

From my Ultimaker Original experiences, 240 degrees is rather high. The same white PLA printed just fine on 210-215 degrees on the Original. Are these common figures with the UM2?

I also made a few pictures of question 2) to make it more clear

[PICTURE LINKS DIDN'T WORK, PLEASE SEE BELOW]

Thanks again.

Michael

 

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You need a Microsoft Live account to view those images, might want to do something about that.

As for the temperature. Yes, the UM2 has a harder time printing fast and needs a higher temperature to do so. The hot zone is absolutely tiny compared to the original so the material has a very short period of time to heat up before being squirted out. I'm at 235C with 0.2mm layers at 50mm/s and my printer is just barely keeping up with that.

 

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I couldn't see the pics either. You can post the pictures on this forum if you want. On the top left of this page, click "gallery", then the upload button. Then after your pics are all uploaded, make a post and click on the "my media" next to the smiley face.

 

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From my Ultimaker Original experiences, 240 degrees is rather high. The same white PLA printed just fine on 210-215 degrees on the Original. Are these common figures with the UM2?

 

The extruder *seems* wimpier on the UM2 than the UM Original. But I could be wrong. It seems to only be able to supply half the pressure. Or maybe as Illuminarti suggests, it's because the melt chamber is so tiny that you need higher temps to print the same volume of material than the UM Original. I think it's the feeder. :)

Anyway, so to print at higher speeds you need higher temps. In general I just print slower on my UM2 than my UM Original. About half the speed. And I get great results. When you have two printers you can afford to be more patient.

:)

 

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It's a fairly well known phenomenon that on short-melt zone printers, you have to set the temperatures way higher than the actual intended target temperature, in order to get the plastic up to working temperature quickly enough.

For instance on the QU-BD Revolution printers, in order to print ABS at their 400+ mm/s 0.1mm layer top end speed, you have to set the temp to 300+ ºC. For more sane speeds, you can get away with more like 230ºC. The problem with fast and hot is that as soon as the print slows down for detail, or comes to a stop, the filament in the nozzle pretty much instantly cooks to the point that it discolors or totally blocks the nozzle. (Thus proving that in the course of fast printing, it isn't getting up to those temperatures).

(Which is not to say that the extruder drive on the UM2 might not be the limiting factor that comes into play first).

 

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Hi there again! Thanks for replying guys. I really appreciate the help.

It's good to know the UM2 needs a higher temperature. Nevertheless I stil have issues with the extrusion and made a few video's of it and placed them on Youtube. I forgot to speak when making the movie :wink:

Here's video 1 - a simple print of one of the gcodes that came with the UM2 on the SD Card. I basically just turned the power on, and hit print.

 

Here's video 2 - the back of the machine with the extruder mechanism. It shows the skipping of the PLA

 

When uploading these video's I started another print again. It's the same red PLA like in the video. The first few layers were horrible again and I changed temperature setting (up to 260) and the material flow (up to 110%) but still with bad extrusion. There was some flow, like in the video, but not enough to make good layers. After a while it started printing normally again! I could even change the settings back to normal (220 and 100%) and whithout ruining the extrusion flow. After a few nice layers it started skipping the material again. :sad:

Besides the extrusion problem, there was the non-90-degrees issue of which I made pictures and tried to share them before. I now placed these in the "My media" on this forum (I found the button :wink:) so I hope everyone can see them now.

 

 

 

 

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What an interesting looking part! It looks like a house with a massive chimney.

So... It's not supposed to rock like that? This is most likely a shrinking issue. The wider the part the more it shrinks. Because the width changes at different points, the shrinkage varies. I suspect if you print a cube you will not see this issue.

I have certainly never seen this issue quite this way. If I print a cube it does not have a curved side like this!

Consider printing this part hollow as the internal fill is partly responsible for pulling the sides in. Also consider maybe printing in a heated chamber. Close the front and put a box over the top and heat it up to 40C (much hotter and the steppers can't take it). Most of the shrinkage issues occur from around 80C cooling down to ambient air temp for that layer. So if you can heat the chamber even only 20C to 40C it makes a big difference. There is also special PLA that doesn't shrink but it only comes in black and white and it costs twice as much: PLA 45.

For me personally - if I was the designer of this part. I would measure it carefully and give the model an inverse bow so that when I printed it, it would come out perfect. Then reprint in identical settings (same fan, same bed temp).

 

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Having the extruder jump back on the first layer isn't too much of a problem - it just suggests that perhaps your bed level is a little off, so that there isn't room to get all of the plastic out. I'd try relevelling it. Also, it's a bit hard to see in the video, but it looks like the bed is quite gunked up with glue. When you apply glue to start a new print, spread it around with a wet cloth until you can't see any lumps of glue any more. Then let it dry as the bed heats up. You might also check your nozzle tip and make sure that it doesn't have any glue caked on it.

0.3mm layers is definitely too thick, I think. Aim to keep layer height x linear speed x nozzle width (0.4mm) under 4mm³/s - at least to start with.

The curving may possibly be cooling/shrinkage related, but another thought is that you might have slightly loose pulleys resulting in a little it of layer creep back and forth over time. Even seemingly very tight pulleys have been known to slip enough to actually let the axis rods totally fall out of their bearings. Might be worth making some alignment marks on the rods and pulleys with a permanent marker, so you can tell if they are slipping at all

 

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I've been ill for a day and a half but back in business!

With the tips of gr5 and illuminarti I got the extrusion going without problems. I recalibrated the platform and removed the excessive amount of glue. My guess the problem I had ealier on were mainly glue related with the nozzle picking up glue from the platform an with that blocking it. I also whiped the nozzle from the outside with a needle. It's working fine now!

I also tensioned the short belts a bit to prevent the curving. I think this is a shrinking issue though so I think I might resedign the part a bit. It's a part of R2-D2's leg by the way :smile: Yes, I did design that myself but I was already thinking of redesigning to make it lighter to save printing time. If you're interested, R2's on Youmagine.(https://www.youmagine.com/designs/r2-d2)

Another good tip was to bring down the print speed. I now print at 30mm/sec (Cura setting) at 225 degrees. Basically I now print with Illuminarti's settings which I found on his wonderful blog, everyone should check it at: http://www.extrudable.me/

Here are his illuminarti's settings to Cura/ the UM2 to get wonderful prints:

 

  • Retraction distance 5.5mm (in UM2's Tune menu)
  • Retraction speed 35mm/s (in UM2's Tune menu)
  • Print speed to 30mm/sec
  • Upped the travel speed to 250mm/s (in Cura on the Advanced tab)
  • Disabled the ‘Combing’ feature (in Cura's expert config)
  • Minimum travel distance at just 1mm (in Cura's expert config)
  • Minimum extrusion between retractions to 0 (in Cura's expert config)
  • Brim line amount to 20
  • Combine everything (Type-A) enabled
  • Skirt line count to 0 (since I use Brim on all my prints)

I always use the Brim support option. This has two advantages for me:

 

  • It gets the extrusion going
  • Better adhesion to the platform

Now on with the printing! Bring it on! :smile:

Last but not least: Thanks very much gr5 and illuminarti! Without your tips and advice I would probably still be struggling.

 

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Hi LePaul,

great to find your R2 page! I made the 3D R2-D2 from blueprints and images found on the internet and gave my own interpretation where needed ;-). I also printed R2 on 0,2mm layer height this summer, scaled 50% of the intended size.

Pictures can be found in my album

http://umforum.ultimaker.com/index.php?/gallery/album/402-r2-d2/

Cheers,

Michael

 

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