doubling of layer when slicer uses z-offset

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  • Avatar
    Brennan Foo

    Hi Rainer,

    Thanks for reaching out, and sorry that you're running into an issue.

    1. What printer do you have?
    2. May I ask why you use z-offset instead of adjusting the build plate? I believe Z-offset affects the entire print (the whole print is 0.07mm lower), so why not raise your bed or lower your nozzle?
    3. When you say the first layer looks too "empty", that to me suggests that the bed is not close enough to the nozzle. 

     

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    Rainer Sonnabend

    Hi Foo,

    thanks for your immediate response.

    1. Renkforce RF1000 (a German product, maybe only available in Germany, but I´m not sure)

    2. I´m aware that the entire print is 0.07 mm lower. But I can´t adjust the flow only for the first layer (at least not with the slicers I know). In this way the flow of the first layer is higher, but the rest is 100%.

    The printer has a build-in "bed leveling system". I think there is a bug in the firmware or in the hardware. No matter which slicer I use (Simplify3d, Cura, Slic3r), the first layer is always too thin/small, the rest is perfect. Till now - without the palette - I always increase the flow of the first layer at the printer device, the rest with 100%. It works perfectly. But with the Palette / Chroma I can´t increase the flow manually only for the first layer, because of the pings - I assume?!

    3. That may be true, but I can´t change it. The printer makes a kind of surface scan with a matrix of points (maybe 400 points, 20 x 20 or so), and for the first 10,15, ... layers the printer software/firmware compensates unevenesses during printing. I have perfect surfaces and no problems with the adhesion of the first layer.

    When I use this z-offset, Chroma seems to use different z-levels for the transition tower and the printed object.
    I use Repetier server and I can see the levels during printing on my PC screen, transition towers and printed objects are always printed on different levels, only the first level is the same one.

    When I don´t use any z-offset, Chroma and Palette are working pretty fine, no twice as many layers, exactly the right number, and also the colors are changing at the right time -  but the first layer is too thin/small.

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    Brennan Foo

    Hi Rainer Sonnabend,

    Thanks for the info! I understand better now why you were doing that.

    So: Chroma cannot (properly) accept G-code with a Z-offset.

    If you are using Simplify3D, however, I think we can remove your need to use a Z-offset by increasing the extrusion multiplier (but only on the first layer):

    Using Simplify3D

    If you are using Simplify3D, then you can create different processes. Let's say you're printing an object with 3 colors in it. You will need up to 6 processes (depending on how many colors appear on the first layer). Let's say that 2 of the 3 colors in the model are printed on the first layer. You can: 

    1. For each color that is printed on the first layer, create a new process that is identical to the other process for the same color.
    2. Then, edit the process: (a) increase the extrusion multiplier as desired (Extruder > Extrusion Multiplier, although other settings like Layer > First Layer Width, Height, and Speed might help), and (b) go to Advanced > Stop printing at height, and set this to the same setting as your first layer height. E.g. if your layer height is 0.2mm and your First Layer Height is set to 100%, the "stop printing at height" should be 0.2mm. You need to do this step for each color used in the first layer.
    3. Then, for colors that are used on the same layer, for other processes, you will need to edit them, and go to Advanced > Start printing at height (0.2mm, or match what you used before).

    The idea here is that you can use different extrusion multipliers for the first layer and upper layers, and Chroma / Palette 2 will account for these changes if you do at the slicer level. This is because changing the extrusion multiplier will actually change the g-code, which Chroma and Palette will account for.

     

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    Rainer Sonnabend

    Hi Brennan,

    thanks a lot for your help.

    I had the same idea, and exactly what you describe above I´ve done yesterday in the evening.

    But the issue doesn´t depend on the z-offset - at least not only.

    Some days before I printed the keychain without offset and so I did it again yesterday. It "seemed" to work, yesterday and before. Description:

    original keychain, z = 7.6 mm, layers = 0.125 mm, 61 layers.

    Simplify3d (without Chroma) prints it with one colour perfect, without any z-offset and even with 2 processes, one only for the first layer as described above. So far so good.
    But when I open the keychain in Chroma (61 layers, without z-offset, without "additional first layers", just two pieces, two colors) and save it for the printer, the printer web interface tells me: 75 layers and also 75 layers are printed.

    Up to layer 41 everythings looks fine, both keychain and transition tower on one layer. But then:

    layer 1 ...
    layer 41: keychain and transition tower
    layer 42: only keychain
    layer 43: only keychain
    layer 44: only transistion tower
    layer 45: only keychain
    layer 46: only transistion tower
    ... (every layer only one of them alternatively)
    layer 67 :only keychain
    layer 68: only transistion tower
    layer 69 .. 75: only keychain

    The printed keychain is ok, but after layer 40 .. 47 I got no more pings.

    So the days before I didn´t pay attention of the missing pings and the uncorrect numbers of layers as the result was ok, there was no reason to check it all.
    (I even found a setup in the printer firmware, where I can manage the z-offset / print bed adjustment, but I don´t use it yet; but I think it will work, I will try it later.)

    Afterwards I took my laptop, install all 3d-software from scratch (I didn´t use the laptop for 3d things before) and I got the same result I got with my desktop pc.

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    Brennan Foo

    Hey Rainer, thanks for the info!

    When you have a chance, could you please send the following files to support@mosaicmfg.com? We'd like to investigate further.

    1. The project S3D Factory File (File > Export > Factory file)

    2. The g-code file

    3. The maf.gcode file

    4. Your Chroma profile (Chroma > Profiles > Export)

    That way we can check out what's going on.

    If these files are big, you can zip them and send them using http://wetransfer.com

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    Brennan Foo

    Hi Rainer, I'm replying here so that others have visibility (and if they run into the same issue, they will figure things out).

    I think I know what's going on. I actually don't think anything is wrong at all and that everything is working as intended.

    You mentioned that the keychain printed fine, (1) but the pings stopped, and (2) that the layers were alternating oddly.

    I believe the layers looking odd is a Simplify3D issue that occurs when you try to preview G-code in Simplify3D when you already had S3D open. I opened the Keychain.maf.gcode file you sent me (and previewed it in Simplify3D) and it has exactly 61 layers like the Keychain.gcode model before going into Chroma. See the # in the bottom right here:

    https://i.gyazo.com/231b794a8502c12491a3bc795adcb492.png

    Additionally, I believe it is perfectly normal for Palette to stop receiving pings after Palette 2 has completed its job. 

    This model required approximately 2600 mm of filament. You mentioned that you received no pings after pings ~40 - 47. Let's say it was ping 47. At this point, the print would be ~77% of the way through the 2600 mm print (leaving about 23% of 2600 mm, or ~600 mm). It is likely that at that point in the print, Palette 2 had finished making filament and the filament will have exited Palette 2. At that point, Palette will not be able to detect any pings (because to detect pings, Palette 2 uses the Scroll Wheel inside the unit). And that is totally fine! Everything is working as intended!

     

    tl;dr - If your prints are looking good, I don't think anything is wrong!

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    Rainer Sonnabend

    Hi Brennan,

    once again thanks for the extraordinary support!

    After some holidays and some days of testing, here a few closing remarks (for other users who may have similar issues):

    a) I recognized not to use any z-offset in the gcode (important to know, easy to avoid);

    b) the last one or two missing pings of a print can´t be detected by the palette, that´s clear, unfortunately in my case some pings before were also missing, no clue why, seems to be inevitable to miss one ping of ten, f.e.;

    c) my printer firmware/hardware (RE1000) and/or the printing software Repetier-Server seem to have some bugs concerning the number of layers: palette, S3D, Cura, ... all show the same number of layers, but Repetier "adds" some layers, not visible, no other effects but the pure number.

    Last but not least: everything is fine with my Palette : - )

     

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