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Spiralize outer contour is not behaving like it used to.

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Posted (edited) · Spiralize outer contour is not behaving like it used to.

To calculate the appropriate flow rate, I add a calibration cube and enable spiralize outer contour. What used to happen was that after the bottom layers were printed, the nozzle would start printing the walls of the cube without any 'breaks'. The nozzle would start printing the outer wall (only 1 wall) in a smooth and continuous fashion. Now, however, the nozzle does these moves that don't stay on the wall (I believe it does these moves for z layer changes). This also results in flow cubes that look really bad; my previous ones used to be perfect.


I'm using the same settings as before so what gives?


EDIT: using cura 4.10.0.

Edited by bassamanator
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    Posted · Spiralize outer contour is not behaving like it used to.

    I have a really good rant regarding the use of any type of wall model to calibrate flow.  I'll spare you and leave it for later.


    I'm not exactly sure how spiralize determines the "incremental" Z adjustment around a circle or curve but for a cube it adjusts at each corner as that is all that is possible since there are only 4 lines of gcode per layer.  There is no "shuffle" in the XY.  As you can see in the snippet below, each move around the square has the same XY as the layer below.


    ;MESH:Ref Block.stl
    G1 X102.7 Y127.3 Z1.45 E240.93544
    G1 X102.7 Y102.7 Z1.5 E241.78243
    G1 X127.3 Y102.7 Z1.55 E242.62942
    G1 X127.3 Y127.3 Z1.6 E243.47641
    ;MESH:Ref Block.stl
    G1 X102.7 Y127.3 Z1.65 E244.3234
    G1 X102.7 Y102.7 Z1.7 E245.1704
    G1 X127.3 Y102.7 Z1.75 E246.01739
    G1 X127.3 Y127.3 Z1.8 E246.86438


    Here is a layer near the top

    ;MESH:Ref Block.stl
    G1 X102.7 Y127.3 Z22.25 E616.08031
    G1 X102.7 Y102.7 Z22.3 E616.9273
    G1 X127.3 Y102.7 Z22.35 E617.77429
    G1 X127.3 Y127.3 Z22.4 E618.62129



    So check your gcode file.  It should be similar to the snippets above.  You may have loose belts or the trolley wheels need an adjustment.

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    Posted · Spiralize outer contour is not behaving like it used to.
    16 hours ago, GregValiant said:

    I have a really good rant regarding the use of any type of wall model to calibrate flow.  I'll spare you and leave it for later.

    Have you posted this rant before elsewhere? Would love to read it. Is there a different way to calibrate flow because the hollow cube is the only method that I've encountered.


    I'll look into the gcode. Definitely nothing related to belts. As I said, in the past, the nozzle would start 'drawing' the walls of the cube and not stop till it finished. Now, it does these non printing moves at every layer.

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    Posted · Spiralize outer contour is not behaving like it used to.

    This is "My Rant" on calibrating flow.  I came up with it with help from a PhD friend who I give full credit to below.


    What is flow?  Most people consider it to be volume over time.  It might be gallons/hr, liters/min, or in the case of 3D printing "mm³/sec".  It has nothing to do with steps/mm and it certainly has nothing to do with how thick a wall is.  That's the first thing.


    Cura knows the diameter of the filament (which you should have measured with a decent caliper and entered into the program) and so it knows the volume of a length of that filament.  Cura knows the height and (theoretical) width of an extrusion and so it knows the volume of the length of that extrusion (as the volume of a perfectly rectangular solid which it is not).  Due to manufacturing variations and the different components involved, there are variations in the printers regarding how many steps the motor-driver sends to deliver a precise amount of filament.  So you calibrate the E-Steps to tell the printer: the exact number of steps to send to the E-motor to push an exact amount of filament.

    So where are we at this point?  Lets see - Cura knows the volume of the extrusion and it knows the length of filament required to provide that volume and enters that length on a line in a Gcode file.  The printer sees that line and knows the number of steps to send to the E-motor to provide that length of filament.  By Jove, I do believe we are calibrated!  Volume In = Volume Out at a 1:1 ratio.  As I said - it's a misnomer (time isn't involved) but let's call that 100% Flow.  Perfect.


    Now that we have Cura and the printer in PERFECT sync how can I improve on that?  Oh, I know, I'll print a single wall cube and measure the width of the wall.  Then I'll adjust my PERFECT calibration to some random number I get by comparing the "thickness of an extruded wall" to my "Line width" (even though the Line Width is nothing more than the index distance between two adjacent lines of extrusion and has nothing to do with volume, "flow", or nozzle diameter).

    Really?  And I'm going to make that adjustment even though I know that in real life one side of an extrusion is almost always constrained by a wall of a previous extrusion that was itself unconstrained on that side?  Really?


    Not me.  When my E-steps are calibrated and in Cura I have my exact filament diameter entered in "Manage Printers | Machine Settings | Extruder 1 | Nozzle Settings | Compatible Filament Diameter" I am done.

    During a print, if I see I'm running a little short on material I will kick up the Flow % to tune the print on the fly.  I know that when printing Silky PLA I get better results if I kick the flow up to 105% (because I don't bother to fine tune the filament diameter in Cura for every roll) but for 99% of the stuff, I'm at 100% Flow where I know that Volume In = Volume Out at a 1:1 ratio because I calibrated it to be so.


    Calibrate the E-steps and you are done.  After that, LOOK at the print and read what you see and then maybe make an adjustment.  It shouldn't have to be by very much, but sometimes it needs to be done.


    Thank you for reading my Sunday morning rant.  Next week I'll cover "bed leveling" which never involves the use of a level.




    with the help of

    Dr. Bunsen Honeydew



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