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I am having two separate issues. One is specific to this particular model, the other is on all my prints, but more pronounced on 90° vertical walls.

The first issue is a localized area of under extrusion only in one area of the print. This issue is specific to this model. The second issue is evenly spaced horizontal bulges that appear approximately every 5mm during the first 30-35 mm of the print. This is a two-piece Christmas tree I designed for my wife and I have been printing both pieces together on the build plate.

I am printing on a mostly stock Voxelab Aquila with Voxelab Gold 1.75 mm PLA. I have changed the stock extruder to the aluminum extruder after the plastic one cracked, and am running a Satsana style shroud with stock fans. I am using CHEP's Cura 4.11 Ender 3 profile for .2 mm (good) - CHEP Cura Profiles, printing at 200 °C and 40 °C bed temp. I have lubed my Z screw with white lithium grease, checked that belts are tight and no screws or physical connection points are loose. I checked to make sure that the eccentric nuts are snug but not binding the gantry. I have calibrated my extruder E-steps and changed the value to 96.

Can someone offer me some guidance on where to go from here?

Photo of a 3D printed two-piece Christmas tree

Photo of the inside of the top part of Christmas tree

Photo showing the printing errors inside the top of the Christmas tree

Photo of horizontal bulges on the base of Christmas tree

Photo of ruler measuring the evenly spaced horizontal bulges on the base of Christmas tree

agarza
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Jared Robinson
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2 Answers2

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The horizontal bands are 5mm apart, which is a common pitch for the screws often used for the Z axis.

I would look for something that binds, moves, slips, or touches once per screw revolution. The movement repeats along the screw, so if it is a screw defect I would look for a scratch or bump that affects the screw along its axis.

If you don't see that, check for how the screw is constrained at both ends. If they are loose constraints, does the screw wiggle while it is turning?

Move the nut to one extreme and rotate the screw. Does it appear to have any bend? Even a small degree of bending that doesn't bind the axis can add a small load to the drive.

The Z-azis error you are looking for is subtle. It is probably 10% (or less) of the layer height.

cmm
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Try setting the z-seam to random in your slicer. In Slic3r it is Seam position under Advanced near the bottom of the Layer and perimeters page of the Print Settings.

Perry Webb
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