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Dim3nsioneer

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Posts posted by Dim3nsioneer

  1. Yes, it means the same thing. The z-jerk setting is already very low by default - 0.4mm/s. Don't know if you've seen my blog post on z-speed; I didn't pay much attention to z-jerk, but I did talk about speed and acceleration as it relates to z.

     

    I had it actually marked for reading a few days ago... :wink:

    After heaving read it now: Has someone played around with z-jerk in the meantime? Obviously to put it to something like 30mm/s is not a good idea. Where is the threshold where slipping at the beginning of the movement starts?

    It might be worth a try after Nick's findings with the higher z speed and acceleration.

     

    Interesting to see that high acceleration seems to give more even results. Any theory as to why that should be?

    [...]

     

    A very good question. If we would transform the transient movement into a power spectrum (by Fourier transform), we would get more amplitude at higher frequencies for the faster movement due to the steeper slopes. Attenuation might be higher for higher frequencies. However, I would expect this effect to be small except we are in resonance somewhere...

     

  2. On a UM1, the head should exactly touch the bed when it's leveled.

    [...]

     

    But only if the head is hot... in the (clean!) cold state which is usually used during the (first run of the) bed leveling wizard, it should be 0.1mm higher (that's the amount of thermal expansion between room temperature and around 200°C).

     

  3. Daid while we are talking about speeding up infill without hurting quality...

    It would be nice if for those times when someone sets the infill speed at a different rate than the print speed, it would be nice if for the last 1 second worth of travel, or the last 50mm or something like that - it would be nice if it would gradually (or suddenly) switch back to the print speed. So that there isn't this bad quality the moment it changes speeds (typically over extrusion when it starts the skin again).

     

    A very small retract at the start of the next skin layer would do the job (decrease pressure within the nozzle), wouldn't it? And the other way round: an additional amount of filament when starting the (fast) infill...

    But shouldn't that not better be implemented in Marlin? Some kind of latency would have to be specified for that in the Marlin code...

     

  4. Actually that creates little vertical spikes. "non-printing" is harder than one would think.

     

    The spike effect could be minimized with a low temperature (which you would anyway use for slow printing the last surface). And not all the PLA blends behave exactly the same...

    But you are so right... this was my major finding when fighting with the dual extruder...

     

  5. As Christmas is close, I wrote a small present for all of you who wants to get rid of the combing lines on horizontal top surfaces.

    https://github.com/Dim3nsioneer/Cura-Plugins/raw/master/RetractCombing.py inserts retraction for G0 movements (combing movements are G0 movements) on a specified height. You can specify the minimum and maximum height (e.g. it makes sense to set 0.49mm as minimum and 0.51mm as maximum if you want to have the plugin to work on your 0.5mm layer). You can specify a minimum distance under which no retraction will occur (default set to 2.0mm). Furthermore, retract distance and velocity have to be specified (the only possibility for prints with otherwise no retraction).

    Optionally, you can also tell the plugin to lift the head (actually lower the z stage) during retraction.

    I declared the plugin as test version and used the same version labeling scheme as Daid for Cura (hopefully, nobody will be confused by this...)

    This plugin might also be combined with the TweakAtZ-plugin setting the speed to a lower value for the last layer...which gives especially nice prints...

     

  6. Must be your magic hands then... :wink:

    I printed it again this morning. It came out ok (with the exception of the hole in the hat). So it was definitively something hardware-related. After having another look at the failed print, I think it might be caused by partial delamination as the print is significantly thinner at one end (and the material difference most probably distributed over the rest of the print).

     

  7. I'm looking forward to these comparisons... it would be especially nice to know what kind of filament was used (material (e.g. PLA vs. PLA/PHA), origin of the material, measured filament thickness).

    Uncoupling the extruder from the frame might be a good idea to reduce vibrations...maybe this is a major difference between UM1 and UM2?

     

  8. I can confirm that with the ovality of the filament. I think every filament has some? Actually, I get a larger diameter when measuring in radial direction compared to axial direction. I usually take the axial measurements as I think the bending around the reel might make the measurement quite arbitrary.

    Thanks for the hint with KISSlicer; as soon as I have set it up for the Ultimaker, I'll give it a try.

    What about the temperatures? Higher, lower or the same as for pure PLA?

     

  9. Thanks for testing! I'll do another one myself. Maybe it was a big coincidence and a different reason...

    EDIT: How did you get the space between the hole in the hat and the hat outline filled? Seems to me a bit like a mission impossible with a 0.4mm nozzle...at original size.

     

  10. Hi there

    I'm having quality issues with Colorfabb signal red PLA/PHA. I get a lot of knots and clearly visible layer structures when printing this material.

    This is a typical example:

    Example Colorfabb signal Red

     

    This print was made with 50mm/s, 220°C for the first layer only, then 205°C until the velocity dropped under 25mm/s due to minimum layer time from which I used 195°C. The filament diameter was measured and set to 2.85mm. The layer height was 0.1mm.

    I do not have these issues with standard PLA. The very same settings result in a very convincing quality with pure PLA.

    Any hints how the quality could be improved?

     

  11. Very nice analysis, Nick!

    I've been doing tests as well in order to get rid of the remaining wobbles. My analysis showed that some of them are rather caused by a variation of the z step or a variation of the flow (due to the last remaining imperfections of otherwise high-quality filament).

    Other wobbles are actually not a variation in print thickness but x/y-shifts which might rather be caused by the z thread and the bed itself (and vibrations of course).

    Which type are your remaining print imperfections of? It's not quite visible from the pictures which are otherwise great.

     

  12. Hi there

    This is a very strange one. I tried to print http://www.thingiverse.com/thing:14195 in Colorfabb signal red PLA/PHA. After having measured the filament diameter I-don't-know-how-many-times I set it to 2.85mm in Cura 13.12-test (worked nicely for other prints).

    After a few prints with serious underextrusion I also managed to get some fairly reasonable settings (not fully convincing quality) such as 50mm/s at 220°C with more or less closed surfaces.

    Then I scaled the model by 2 in z-direction, i.e. the thickness was set to 5mm from previous 2.5mm. I was actually baffled by the result.

    Snowman Over-Extrusion

    The print is 'normal' (which means about the same quality as the original 2.5mm print) up to 2.5mm. After that point, an enormous overextrusion happened.

    I put this into the Cura section as I think it is rather a software than hardware issue (would be quite a coincidence if my Ultimaker decides at exact the original height to go crazy, wouldn't it?). However, it could also be the model itself. I just had a look into it and for me, it looks ok...

    Any ideas?

     

  13. So, it's pure PLA and not PLA/PHA as Colorfabb has it? Is it brittle or easy to bend?

    I see this knots only with the PLA/PHA mixture, not with pure PLA. I also think to remember a post, where the topic was bridging. Someone tried to do it with PLA/PHA which also resulted in a lot of knots.

    Anyway, you're right: it's not oozing. Oozing looks different.

    Did you have a look at the ooze shield while it printed? I still have the impression that it is printing each ooze shield line twice, once for each extruder on the same layer. This usually results in an enormous blob right after the ooze shield for the extruder that is used as second on that layer. Maybe you can confirm that issue?

     

  14. I guess you're using Colorfabb PLA, right? The knobs at the color junction look quite familiar...it's something I dislike with the Colorfabb PLA. I also recognize the very prominent horizontal lines...

     

    ...

    wait for someone to come up with a plugin to switch extruders every layer :)

     

    Such a plugin might be possible, but not is not trivial... (when starting with a 'single' extruder print)

     

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