Dim3nsioneer
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Posts posted by Dim3nsioneer
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Here is some update. In order to check / rule out the electronics, I swaped the x and the y axis, i.e. the x motor was driven by the y stage and vice versa.
The original deplacement along the long edge is significantly smaller (green arrow). However I got a new displacement in x-direction (red arrow). Thus, it's rather not the electronics as the major displacement is still in physical x direction (actually in direction of the fan).
I also measured the temperatures of both x and y motor with an infrared thermometer. While the x motor was something like 48°C warm, the value for the y motor was 55°C or even a bit higher. A quick look at the stepper drivers showed that they have indeed a different setting. Wasn't there once a page in the Ultimaker wiki showing in which direction you have to turn to increase the current? Can't find it anymore...
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Sounds as if the number of steps per mm is wrong in the firmware. I guess, you compiled your own version of Marlin or built it at marlinbuilder.robotfuzz.com? If it's the second, check the number there; it should be 8/3*200=533.33333 (as long as you use the standard z thread and motor). If you have an Ulticontroller, you can check there.
EDIT: You can also use the M92 code in your start.gcode (UM1, correct?)
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This is the result of the hollow version:
The difference is that there is only one step instead of three (one right, one left and another one right).
I listened to the z stage again. No real difference audible. That one was false alarm.
@znib: I use Cura 13.12. And I have a Marlin version compiled on marlinbuilder.robotfuzz.com. Therefore I also did a quick check with the standard firmware uploaded by Cura today: same result.
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:angry: This is not fair...
After having installed belt tensioners for both (x and y) short belts, I get wonderful prints in really high resolution - with the same crappy step!!!
As I had to remove some cables I even decided to separate the x motor cable from the extruder cables in order to eliminate the extremly unlikely possibility of cross-talk between the two... as you can see, I'm slowly running out of ideas...
While this print was running I listened to the printer. I had the impression (very biased!) that the z step sounded differently at exactly the height where the troubles begin. It was kind of smeared, longer than the usual 'zac'... Letting the z stage make 0.1mm steps brought no real news. The steps do not sound the same for one rotation. But none of them really sounded as strange as during the print.
Any other ideas?
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This is a quite nice overview of some patents expiring within the next few months:
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Although I can only 'see' the non-roundness of the holes with calipers it's certainly worth a try. And it will feel good to print something else again than just the same puzzle piece over and over again... :roll:
Thanks for the moment! I'll give you feedback as soon as the belt tensioners are in place...
... short belt tension is critical to good print results.
Maybe Ultimaker gets rid of the short belts for the third generation printer...? Does the UM2 have short belt tensioners included?
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[...]
Maybe your problem is caused by backlash. When the geometry of the part changes, the path of the print head has to change too, and with a different path, backlash can have a different effect. I strongly suggest to use belt tensioners for both, the long and the short belts, to get rid of backlash. Another sign for backlash would be, that small holes of around 6mm diameter are not printed round.
I thought of that too. Indeed I had some non-round holes in the past and still got sometimes small spaces between shell and infill (only at some spots, not everywhere). However I would expect backlash to show up as well when rotating the print by 90°...
I have belt tensioners for the long belts. They are really tight and make exactly the sound the should when picked (as shown in the Ultimaker video). So far I haven't seen a good solution for the short belts and in the middle to long term I plan to implement a direct drive. I think the short belts are not an ideal design.
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Yes to the first and no to the second (actually not yet, the parts are waiting to be assembled and some of them to be manufactured)...
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Some additional information:
- The print with solid infill every 5 layers looks the same as all the others: deplacement begins a the height where part of the model gets a solid infill
- The print with 100% solid infill also has a deplacement. But it begins where the model gets narrower.
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I don't really have much to contribute but I will say that I've seen the same effect on my prints and it always happens on a transition between a uniform layer to an "uneven" layer like in your model. I always figured it was due to a combination of slight inaccuracies in the rapid move and shrinkage since a solid layer is often laid down where it happens (solid layers shrink more than infill layers). I never bothered to do anything about it though because it was never as severe as in your model.
Thank you for confirming the general existance of this effect! I guess this model shows it much better than other models such as figurines or similar... If it's possible it would be interested to know if in your prints the effects is stronger on the fan side (assuming you only had one from one side...) I have the impression it is strongest on that side...
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I would love to help print this part because this is an interesting topic for me but I am away from my printers until Monday night.
Uuh...you're going through a very hard time then... without any printer... :smile:
No, seriously... as I understand, you have both Ultimaker models, correct? If your original Ultimaker model still has one fan it would be a very interesting comparison between the two...
I'm right now doing some more tests. Just for really, really, really making sure Cura is not responsible, I sliced the part with Slic3r and got the very same result. Doing the infill before the shell (possible in Slic3r, not in Cura) didn't change anything either. The same goes for adding 0.06mm filament after each retraction (equal to about 10mm printed filament at 0.1mm layer height). It just gives more stringing and over-extrusion.
Right now, I'm trying the print with a solid infill every 5 layers in Slicer. After that I think I'll do a 100% infill print.
BTW: There is no difference between 0.8mm and 1.2mm shell thickness...
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In the meantime this is becoming a case for CSI Ultimaker I guess...
Yesterday, I did a few times the same print at different locations on the print bed. It turned out the effect ist strongest on the right side of the print bed and weaker on the left side. It also gets stronger towards the back of the bed.
I've scaled the model in z to 2/3 in order to check if the displacement also changes height. It stays relative to the model, i.e. it was happening at 2/3 of the original height. This is actually the only thing that is clear to me so far: it must have something to do with the rectraction. The deplacement starts on the first layer where the first retraction with a significant move in between takes place between the larger and the smaller structure of the print. And it seems only to happen when the retraction goes from the small structure to the larger one (underextrusion-theory).
As suggested by Illuminarti, I also deactivated combing and set the minimum travel distance for retraction to 5mm. It looked exactly the same as with coming.
Next test was to leave z dimension as it is and to scale x dimension by 2 and y by 0.5. The size of the displacement stayed about the same (no scaling).
I then mirrored the print along the y axis. What I got was a (smaller) displacement at the small structure and no displacement at the large structure.
Next try was to print the model on the second extruder with the same filament. The result was the very same as for extruder one. Thus, it's nothing related to a single extruder.
The final test was exchanging the filament to Colorfabb which is known to have a diamenter between 2.80mm and 2.85mm (i.e. reasonably thin to fit through the Bowden tube). The displacement was even more pronounced in this print.
When looking a this very distinct pattern of this last print I decided to check what's really different on the layers with displacement. I found that on these layers Cura, first lets print the shell of the small structure, then the shell of the large structure, then the infill of the small structure and finally the infill of the large structure.
Below the height the displacement starts, there is only one shell for both structures. On these few layers above the first displacement zone and below the second displacement zone, it first prints the shell of the larger structure and then the shell of the smaller structure.
I'm beginning to wonder if my Ultimaker does something which really no other does (bad airflow?) or if this is an issue that will occur on every Ultimaker. So if someone else would like to print this model, I would appreciate it. Please just print the part no. 2 exactly in the way Cura aligns it.
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I tried to scale it 100 times in Blender and Cura can load it now, so thank you very much.
However, I do not understand why it is so small in Cura. In Blender, its dimension is 6mx6mx6m, and its side vertex is at 2m,2m,0m. Is there any tricky setting in Blender that make this happen?
Make sure you have set the units in Blender to 'metric' instead of 'none'. If it's set to 'none', Blender will use so-called Blender units. I think, one Blender unit is something very tiny like 0.1mm or even less. If you use Blender usually for creating 3D models then it's recommended to change this setting permanently by saving it in the startup-file.
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Welche Nachteile handele ich mir da ein? Ist dann die manuelle Verstellung am Drucker nicht mehr oder nur noch für einen Layer möglich?
Kann ich leider nicht so genau sagen, da ich einen UM1 habe...
Nebenbei: wie kann ich durch ein Plugin den Fan verstellen?
Der G-Code lautet M106 Sxx wobei xx eine Zahl zwischen 0 (0%) und 255 (100%) ist. Da gibt's glaub' ich noch kein Plugin, dass das macht. Würde aber gut ins TweakAtZ passen (gute Übung?).
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TweakAtZ 3.0.1 verwendet den RepRap-GCODE um seine Infos zu bekommen. Funktioniert beim UM Original, nicht aber beim UM2 mit UltiGCode. Dieser GCODE hat keine Infos zu Temperaturen drin, da der Benutzer dieses Einstellungen direkt am Drucker wählt. Um das Plugin trotzdem auf einem UM2 nutzen zu können, muss in Cura in den Maschineneinstellungen der Flavor von UltiGCode auf RepRap umgestellt werden.
Danke für den Hinweis. Da ist wohl eine Version 3.0.2 fällig, die den UltiGCode 'abfängt', d.h. wenigstens nichts dummes anstellt wie Temperatur auf -1 setzen.
Generell dürften die meisten Plugins Probleme auf einem UM2 mit UltiGCode machen.
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Hi Sander
I'm a bit confused... :wacko:
Could you please give some more details which printers are affected? UM Original and/or UM2? Direct print via USB or from SD Card? Is the bug actually in Cura or Marlin?
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Meistens hilft es (bei neueren Versionen jedenfalls), Cura rasch zu schliessen und wieder zu öffnen. Subjektiv würde ich sagen, man konnte früher einen Hot-Swap (d.h. während der Ausführung von Cura) bei den Plugins machen, was heute nicht mehr geht. Scheinbar wird der Code schon mit Cura zusammen geladen (geht dann beim rechnen wahrscheinlich schneller).
Nimm Dir doch einfach mal ein einfacheres Plugin (z.B. das PauseAtZ) vor und schau es Dir an. Speziell ist eigentlich nur der Header, wo die Angaben über die Eingabefelder etc. drin sind. Der Rest ist 'normales' Python-Schreiben. Für den Header-Inhalt findest Du ein paar Angaben http://wiki.ultimaker.com/How_to_write_a_Cura_plugin(falls Du die Seite noch nicht entdeckt hast). Falls Du Dich mit dem GCODE noch nicht so gut auskennst, findest Du eine Übersicht über den 'normalen' RepRap-GCODE http://reprap.org/wiki/G-code. Die Anführungszeichen sind deshalb, weil der Ultimaker2 einen erweiterten Code-Satz (namens UltiGCode) verwendet.
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Fast alle in der Ultimaker-Wiki aufgeführten Plugins kranken leider an einer Änderung im generierten GCODE, die mit Cura 13.06 eingeführt wurde. Aber es gibt Abhilfe: http://umforum.ultimaker.com/index.php?/topic/2454-cura-13064-plugins/
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In addition to the underextrusion I see your skirt lines do not touch each other. This is a typical sign of a to large distance between nozzle and printbed at the first layer. So maybe cross-checking the bed leveling with the famous sheet of paper might be a good idea.
To eliminate the underextrusion, precise measuring of the filament diameter is a good starting point (e.g. with digital calipers).
Finally it is recommended to have a multiple of the nozzle size as shell thickness (i.e. 0.8mm or 1.2mm).
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This is getting interesting... :blink:
First Q&A:
It might be some sort of cooling/shrinking effect due to the larger volume of plastic making the flat surface at that height. Might also be partial under-extrusion due to the head oozing on travel moves associated with that flat surface.
Are you printing infill faster than perimeters? You might also try disabling combing, and see if that makes a difference.
The infill is printed with the same speed as the perimeters, with 100mm/s (I wrote 50mm/s in my original post by mistake). I haven't yet tried to deactivate combing, but it's on the list (see also below)...
Looks exactly like what I would expect with shrinking effects. When you have a long part it shrinks more at the ends than two short parts.
You can compensate for this all in the model by measuring the final sizes accurately and increasing or decreasing only those sides that need it.
Just to make sure we're talking of the same side supposed to be (more) affected by shrink: If you print a cuboid, let's say x=10mm, y=30mm and z=15mm, which dimension would you expect to shrink (more)? The effect I see let would let the x-dimension decrease, but just in the upper 7.5mm...
And it's getting even better:
- I rotated the part by 180°C around z. The deplacement stays on the same side of the print, but is now on the opposite side concerning the printer (which cancels any theory about cooling from the left side only).
- I mirrored the part along the x axis (the displacement occured on the minus-x-wall). After that, it occured still on the minus-x-wall (still the upper half). The plus-x-wall shows no sign of deplacement.
- I rotated the part by 90°C (once clockwise, once counterclockwise). There was no deplacement at all! I have to mention that the rotated part were at dfferent places on the print bed than the original print.
I'm currently thinking of some strange coincidence of retraction-fault (place-dependent?) and/or some kind of uni-directional backlash effect.
I'll do some more tests such as compare the results when printing at different places on the bed, deactivation of combing, etc. I will also have a closer look at the extruder and Bowden tube as my filament has a thickness between 2.90mm and 2.97mm and therefore quite some friction in the Bowden tube (this might be the time to try the oil trick...) Using some other (thinner) filament might be worth a try too.
Finally there should be a test on the other extruder as my Ultimaker can play in stereo... :smile:
But further ideas are still welcome! Thanks so far!
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Some time ago I found that my x and y rods could slip along there axis (one of them by about 2mm). Today I finally fixed this with an adjustable end cap (http://www.thingiverse.com/thing:54075). The play is now something like one or two tenth.
And I found the 'z wobble' became much smaller! So it's maybe a good thing to check the rods in order to give the vibrations no chance to produce a displacement.
I'll have a look if I find some 'before-after'-pictures...
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Hi there
Is there such a thing like geometry dependent displacement?
I'm currently trying to print this interesting 3D puzzle: http://www.thingiverse.com/thing:23279
And this is the result of part 2 (printed twice, one of them rotated around z by 180°):
While the overall print quality is nice (layer height 0.06mm), there is a very nasty displacement in x direction at about half height. It is at the height where the geometry changes significantly.
There is a retraction and a movement between the smaller tower (blurred in front in picture 1, on the left in picture 2) and the rest of the structure during the upper half of the print. The movement is carried out with 150mm/s while print speed is 100 50mm/s (edited); temperature is 210°C (pure PLA). Top and bottom shell are 0.8mm, infill is 24%; infill overlap is 10%.
My first thought was backlash. But the belts seem tight, the axes cannot slip (anymore). And if it's backlash one would expect the (retraction) gap to be smaller than supposed, but it's actually wider (there is also a very small displacement on the small tower outwards, but not as pronounced as the displacement on the larger part).
The funny thing is, that the opposite wall doesn't show any effect at all! The same for the other direction (y).
Next thing I checked was the model and the sliced code. The model shows no traces for any displacement. I even checked the x coordinates of the wall in question in the GCODE for different layers (lower half vs. upper half). They are identical to the second position after decimal point.
I had such displacements in other prints at heights where the geometry was changing significantly (e.g. the Ultimaker robot; different layer sizes when printing the arms). But they were never so isolated and well pronounced.
The most interesting thing is: When printing part 1 of the design (the same shap but mirrored), I don't have any displacement at all...
I'm open for ideas and hints...they are highly welcome!
EDIT: print speed was higher than written originally (corrected)
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Just my two cents.
At the beginning of every z-step there is a breakaway torque between z-screw and nut to overcome. Slow acceleration would increase the time until breakaway torque is reached and - within that time - transfer unwanted movement to the nut, causing some displacement in x/y/z. Fast acceleration will overcome the breakaway torque almost instantly and therefore transfer less unwanted movement to the nut / print bed.
A very interesting thought!
Brings us back to the question if the pattern is the result of a displacement or a thickness variation...
My UM1 is behaving quite well at the moment concerning these wobbles. I'm using 10mm/s and 1500mm/s^2 for the z axis. I also find the wobbles much smaller at 0.06mm layer height compared to 0.1mm.
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Wishlist for Christmas? :smile:
Which Cura version are you actually referring to? I have the impression Cura 13.12-test allows for very small distances between objects (as long as the gantry height is set to zero).
EDIT: Ok, after having tried it again with Cura 13.12-test I have to agree: the manual placement still is delicate...
Nasty displacement - solved
in UltiMaker 3D printers
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I 'feared' it would come out fine... at least we know now what it should look like... :wink:
I'll also test the 50mm/s and 225°C settings. And I just switched back to yellow PLA as the green one has the displacement too but it's less visible on the pictures.
To the term 'displacement': Maybe it's the wrong name. As the geometry changes at half height, it is quite difficult to say if it's a shift or if it becomes narrower.
Yes, it's exactly that way. First, the print narrows suddenly for maybe three or so layers and then recovers for something like two layers and then narrows again. Then it comes very slowly back nearly to the original position until the print is finished (this is not visible in the images). However, I would expect a classic underextrusion to show up all around the print. But it's only on one side...