Stopping Z Wobble
If you look closely at a FDM 3D print you will see that it consists of hundreds of layers of plastic on top of each other to produce a 3D shape. If things are set up properly than these layers should be one uniform smooth surface, However over time you may notice that these lines may shift and leaving noticeable lines and ridges in repetitive patterns throughout the print (every 10 to 15 layers or so).
This in the 3D printing world is known as z wobble, It is a common mechanical problem found in Cartesian style printers.
Basically your z-axis threaded rods are either not positioned properly, loose or are slightly bent, as the z-axis raises for each layer a slight wobble may occur if there is any looseness or miss alignment with the z-axis.
This will result in a wobble effect that is visible in your print.
How can I combat z wobble?
Many community made solutions are available through model sharing sites such as Thingiverse or MyMiniFactory for free, trying out a few of these can usually solve this problem quite effectively.
After printing two of these basic z wobble clips I started to see a vast improvement in my prints, these prints help keep the z-axis inline and eliminate any slight bends within the threaded rod that may contribute to z wobble.
As you can see there is a significant reduction in the rippling effect on this print in comparison to the first image at the top of this article, but still some work to do.
If you continue to see effects of z wobble then this may be a sign of poor motor controller micro-stepping, this is an issue found in the firmware of your 3D printer.
This can be resolved by reinstalling your firmware for you printer, I would recommend talking with someone who understands how stepper motors work with your model of 3D printer or even possibly contacting your 3D printer manufacturer before adjusting any firmware settings.
Tell us how you deal with z wobble, comment below!