Z-wobble on a Delta with 0.01 deviation?

I made a test print in vase mode from a tripod. Although my state_of_the_Art Kossel XL with linear rails, Smart effector and Magball arms calibrates to a deviation of 0.01 or better, I get wobbly prints. The wobble takes place at straight perimeters, so I can outrule backlash.
The distance between valleys varies with print height, but the diameter of the print also varies, so I can't be sure, what's causing the variation. I've marked them on the print. They appear on all three legs, which are oriented towards the towers.
Maybe I should print the same, but rotated 30°?



Any clues?

I made the same part rotated 30°. It's still the same: no straight perimeters, when in vase mode. I reduced extrusion to 92%, to see if it's a squish-issue, but it's not.
I checked other (solid) parts and they are dead straight.

first things first: I'm only guessing.

how much is th wobble? - as I see on the picture reflection of light changes. - could be very low amount of wobble.

If it is very low ammount, maybe it is the imprecision in positioning of the nozzle, because of delta calculation. Even if you have 1/32 stepping, it is stepping. Depending on the height and position where you are printing, imprecision between wanted position and achievd position changes - more or less.
If you print a solid object, maybe the squishing of the perimeters helps to put the new melted filament in the wanted position, even if the nozzle in its achieved position is some 1/100mm off.

You're not seeing wobble, you're seeing the result of stresses caused by the thermal changes in the plastic during the printing process. Check the corners with a microscope. If the registration is good there, then you're not having a z wobble problem.

Try printing that structure with more than one perimeter and a little infill. All that waviness will disappear.

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Ultra MegaMax Dominator 3D printer: [drmrehorst.blogspot.com]