Can't seem to fix over extrusion

  • I'm struggling to get my printer up and running for a few days now. The problem is as follows. I got a test model of a cube (40x40 mm) and everytime I try to print it, the nozzle creates these 'lines' on the print which is caused by over extrusion I think? See image:

    test print aborted at bottom shell

    This goes on for every bottom layer and ultimately when it starts printing the infill the nozzle starts digging into the print and I'm forced to stop the printer, see image:

    test print aborted during infill print

    What I have tried so far:

    • Calibrating my extruder (by marking 100 mm on filament and command extruding 100 mm, check difference and adjust E step/mm accordingly)

    • Performed an auto bed leveling

    • I even halved my flow rate in the slicer (Ultimaker Cura), this gave signs of under extrusion of the first layer but the second layer looks over extruded again

    • Tried different temperatures in the range of 190-210 °C (I'm using PLA), made no significant difference

    My settings and gear:

    • HE3D K280 Delta 3D printer

    • E3D V6 Volcano hot end (original, not chinese)

    • E3D Titan Extruder (original)

    • Marlin 1.1.8 using Ultimaker Cura as slicer

    • Nozzle 0.6 mm, layer height 0.2 mm, print speed 50 mm/s

    • 1.75 mm PLA

    If anyone could help me fixing this that would be great!

    seems to be a overheat vs print speed, remember that your first layer should be 80% as maximun your nozzle diameter. and the speed must be higher is the temperature is also higher and this must be higher is the nozzle diameter is wider. So yours parameters must not the same as nozzle 0.3 or 0.4 mm. verify your nozzle temp, should be differences each 5°.

    Long shot, but I'm out of ideas solving this puzzle: "Is the nozzle size selected in the slicer 0.6 mm, but is your actual nozzle (by accident or wrong delivery) a 0.4 mm?".

    @0scar this explain why those small mount of plastic on the side on each line, seems to be an uncovered area due an irregular overlap on YX movement. The XY movement is waggled

  • Your images look as if your initial nozzle to heat bed offset is too large. This causes the filament not to be squished. Try re-levelling and have a piece of plain printing paper have a little drag when pulled.

    Hi Oscar, thanks for your answer and edit :) Unfortunately I already tried this method (leveling with printing paper) multiple times without any result..

    Maybe this has nothing to do with it but when I'm printing it looks like the nozzle pushes away the previous layed line forming the stripes you see on the picture. Almost like the line are too wide and the nozzle pushes away the excessive material

    @Mikelo That is strange, it really looks as if it isn't squished. What about your steps/mm of the Z axis?

    my Z steps/mm is 80 (default in marlin, have not changed this)

    @Mikelo Default says nothing, it totally depends on your mechanical layout (lead of screw) and electronics (micro stepping, stepper type). If you raise 50 mm from the menu, does it reach 50 mm?

    Yeah at first I thought this was a z axis problem too, but I don't understand how that would manifest in a delta like OP has...

    @R.. A delta uses belts and pulleys or lead screws, but indeed, the carriage is homed at the top, which is defined in the firmware (as Z max), when the carriage drops down to Z = 0 it should be at paper thickness distance. My comment was meant as in: "Don't take default for granted".

  • I would look for Z-axis compliance or springiness. If the Z-axis is too compliant, then it will have a "slight drag on a piece of paper" over a significant commanded Z height.

    When printing the first layer, the head will be elevated by the pressure of the plastic being extruded pressing against the bed. When printing the second layer, the actual Z-height won't be a full layer higher, as the previous layer was lifted. The second layer will also be lifted, but it will drag through the first layer.

    To test for this, manually set the z-height using a metal feeler gauge. If you don't have one, use a strip cut from the side of a soda can. Set the z-height so that there is some like pressure against the gauge. Increase the height by 0.1mm. The gauge should now be free. If not, continue increasing by 0.1mm steps until the gauge is free. That is how much compliance you have in the feed.

    From a home-designed delta I built, I know that there are several sources of this compliance.

    First check the 12 joints. Are they tight? Do they have wiggle room? That wiggle room can destroy your precision. Try squeezing the pairs together at the top and bottom with rubber bands.

    Second, check that the print head carrier (the part that moves around) is stiff and doesn't flex with pressure against the nozzle.

    Third, check that the vertical travelers are following their tracks tightly. There should be no wiggle room for them, either.

    Fourth, check the belts, which must be tight. If there was no vertical wiggle in test three, they are probably OK, but tighter is usually better.

    Thanks cmm, I checked for any sources and noticed the printhead carrier was not properly fixed (flexed a little) but still got the same results (more or less). I also noticed that the Z-offset I entered in my firmware doesnt have any effect at all which resulted in my nozzle being too close to the bed. I fixed this by just altering the delta height but when I set the height to the point where I have a little drag I still got the same results. Now what did work for me was setting the height so the nozzle leaves a gap of around 0.3mm to the bed, however I dont believe this is good practice..

    What are you using as a layer height? My first printer worked best with 0.27mm layers throughout. The Prusa3d i3m3s I'm using now sets up with a 0.2mm first layer regardless of the layer height for later layers. Q: when you measure the Z-height of the head, is it with the bed at operating temperature? Q: The printer you are using has auto-level (from internet information). This may override any mechanical adjustments you are doing. Q: If the printer has auto-leveling, there may be a thermal dependency. Deltas are difficult to calibrate, as they don't have a linear relationship ----

    --- between motor positions and head position. They are also prone to errors from all the slight manufacturing defects. I've built "delta" CNC machines with 6 DOF to calibrate, and they are easier than these 3 DOF positioning systems. Have you tried printing on a raft? If you can get the first 3 layers to print and stick, by layer 4-5 irregularities are usually sorted out.

  • I think You need to re-calibrate Z steps. Sometimes Marlin default z-steps/mm won't fit for 3D printer, because it depends on the hardware(z-axis threaded rod) that used to build the 3D printer. Check whether the Z-axis moves the distance that you command it to move. (ex: command to move x distance and check whether it moves the commanded distance)

    ehhh, no. The last shows the bed is VERY unlevel.

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Content dated before 7/24/2021 11:53 AM