How to fix bulging first layers of print?

  • The bottom 1-6 layers of my prints always bulge, like an enlarged elephant foot effect. I've tried all the fixes for elephants foot to no avail. I'm using:
    XYZPrinting DaVinci Jr 1.0 Pro with their own brand filament (1.75 mm), nozzle: 0.4 mm, tried various layer heights 0.1-0.3 mm, with temperatures 190-205 °C. It has a non-heated bed, using tape as an adhesive.

    Problem can be seen here:

    Part showing bulged out bottom layers
    Part showing bulged out bottom layers

    Have you tried to add an additional z gap in the slicer or use a slightly thicker paper to level the nozzle to the bed? Your first layer may be too close to the bed.

    Since the effect extends past layer 1,2, I'm wondering if this is over extrusion, rather than Z-compression. Nice clear photo.

    That's an elephant foot. What are your temperature settings for hotend and bed?

    i see that if it's windy in the room with the printer. try a partial enclosure.

    Does the effect disappear when print cooling fan speed is reduced or the fan turned off? Does the effect change if the number of bottom shells is reduced?

    Was this ever resolved? I'm getting exactly the same results as the OP (i.e. all bottom layers of my prints are compressed causing elephants foot)

  • You specify that 1 to 6 layers are expanded.

    Does that match with the number of bottom perimeters you ask for? If so, then I would suspect over-extrusion.

    If not, it could be a combination of two problems:

    1. The head is too close to the bed, and

    2. The head has too much vertical compliance or springiness.

    In this scenario, the head being too close puts additional upward pressure on the head. The springiness allows the head to displace upward, but it is still too close. Being too close, the extruded bead is spread out too far. With each additional layer, the head is relatively less close, and the effect reduces until eventually the head is not displaced by the extruded bead, and the object prints normally.

    Are you implying in the second problem description that the gantry e.g. rests on those springy z-screw couplers resulting in this effect? This printer does not have such a coupler.

    I am only suggesting that vertical compliance from any source (such as loose linear bearings) could be a cause of the elephant's foot lasting for 1 to 6 layers.

    I don't really buy argument #2. In my experience the plastic has trouble exiting the nozzle if the nozzle is too low. There simply isn't enough pressure in the nozzle for the exiting plastic to be able to lift the extruder.

    @nathan-headlay The problem is only the point 1 (adjust Z offset), some times the Z height is not enough tall to allow the PLA flows correct , then affects the second and the third layer or even the fourth if the layers height is too small. I got that when I move the printer and skew the Z tower by error, then I need to adjust the Z axis to 90° again.

    @0scar The second point is correct also, this spring comes from bed springs and a kind of loosening of the X rods, if you move that part with your hands you will have movement on Y axis like spring which is enough to hide or compress at leat 2 layers. This compression disappears when the Z goes up until friction is nulled.

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