Z-axis instability is one of the most common problems in DLP/MSLA (LCD) 3D printing. The reason of z-axis instability is usually due to the assembly of z-axis slider, or wear or looseness caused by repeated up and down mechanical movement. When the z-axis instability occurs, the forming platform will not fall to the same position accurately during each return of the up and down motion, which will cause undesirable printing lines and even layer offset between layers.
First, consider more advanced mechanical components. A common solution to z-axis instability is to replace the original slider with two axis linear guideway system. The biaxial guide makes the forming platform more stable, does not need to be adjusted repeatedly over time, helps to maintain stability in motion, and ensures that the forming platform does not offset during the printing process, ensures that they maintain linear motion and minimizes the effect of loading force during the printing process.
Secondly, check the parts for wear. All parts have life and some parts will wear over time. Therefore, make sure that the screwsball screws and bearings are regularly maintained, lubricated and in good condition. If there is wear, parts need to be replaced. If you hear any rolling or rubbing sound, be sure to recheck the leveling process of the components and forming platform.
Again, check for loose parts. Check the nut on the z-axis lead screw. If there is excessive clearance (looseness), it may also lead to unstable z-axis ripple during printing. Usually the nut has a second loaded spring nut, which can cause problems if it is not properly installed (or worn).
In addition, z-axis instability may also occur due to screw bending or off center. At this point, the screw must be replaced.