[solved] (speed issue) Layer Width Question



  • Hi,

    In this video

    https://www.youtube.com/watch?v=Z-DxiqxSN3g&feature=youtu.be

    You can see that there appears to be an issue with the layer width. This is being printed with

    .8mm nozzle,
    1mm extrusion width
    .4mm layer height.

    However, when it prints it seems like the extrusion width is actually about 1.7mm which obviously is quite large and causes ridges in the print, which the nozzle hits causing missteps.

    Currently, i am bringing up the Z-height a little bit at a time but it doesn't seem to be doing any good, so i was wondering if I'm on the right track or if there is something i am missing?

    Thanks!



  • did you put the correct nozzle size in your slicer?



  • Yes. I have just verified.


  • administrators

    Looks to me that either the nozzle height isn't accurately 0.4mm when printing that first layer, or it is over extruding. Have you calibrated the extruder steps/mm?



  • This is with it nozzle raised about .25mm from the first video. It is strange. It prints two lines at about the right width (maybe?) the skips a line, then prints another two.

    https://www.youtube.com/watch?v=fuQcIBc4oG0

    EDIT:

    I have calibrated the extruder with a .4mm nozzle, I did not recalibrate with the .8mm nozzle. Do you think that is necessary?



  • Yes, always recalibrate when changing something on the extruder/nozzle side! It only takes like 5 minutes.
    Every time I buy a new type of filament, i do a calibration and save those values in the filament gcode section of the slicer.



  • What method do you use?



  • Hi guys.

    Unfortunately I am still not getting a sucessful print with this larger nozzle.

    I have recalibrated my extrusion, decreased the extrusion width, and recalibrated my bed leveling. I have also verified z-steps per mm (by putting the nozzle at bed level, then lowering the bed by 100mm and measuring).

    The first layer looks pretty good now, the second layer is terrible. It looks like it is too high. I’m not sure though. What ends up having is that the nozzle digs into the plastic, and then skips steps. I haven’t kept track of if it is at the same exact spot each time, but it never makes it past the second layer and never fails before the second layer….

    I have cross posted this here

    http://forums.reprap.org/read.php?397,766203,816414#msg-816414

    But if I get a solution there I will update this topic



  • what slicer are you using? most i have used do some extra extrusion on first layer including hidden settings. for example, slic3r has a setting for first layer thickness separate from the others, plus if you look deeper there is a default to do 200% extrusion on the first layer.
    so i would suspect that you now have the bottom of the first layer correct, and now have to think about the top of it.



  • Thanks. Currently i have the first layer height set at 100% and it’s extrusion factor at 100% So, the first layer and second layer should print at the same settings afaik.

    Actually, except for speed. O lampe suggested checking the print speed and temperature going from the first layer to second.



  • Yes I agree. Speed will be very important. The area of a 0.4mm nozzle is about 0.125mm^2 and the area of a 0.8mm nozzle is about 0.5mm^2 so about 4 times greater. Therefore, if you were used to printing at say 60mm/sec with a 0.4mm nozzle, you need to drop the print speed by a factor of 4 to say 15mm/sec to keep the same filament flow rate. If you are printing with a larger layer height, then you need to drop the speed even lower. If you print to print large layers at higher speeds then you need a hot end capable of high melt rates like for example a volcano or Diamond with 3 melt chambers employed concurrently.



  • Yea, the temperature stayed pretty steady but I think the aero extruded just didn’t have enough torque to pull through .4mm of filament at 60mm/s

    I tried 40 mm/s and it got 4-5 layers deep before failure so I lowered it again to 30 mm/s and it seems to print fine 8 hours in.

    I didn’t hear any clicking from the extruded, so my guess is that the cog was just grinding on the filament slipping in it.

    Unfortunately I’m out of white pla due to all the “testing” so I put the printer on pause while I wait for some more.

    Thanks.


 

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