Shims are elements that mechanically correct the Z offset when printing in Mirror or Duplication mode.
In these modes both toolheads work simultaneously, so it is key to make sure both nozzle tips are exactly at the same height. Due to manufacturing and assembly tolerances, the Z offset between tips can be up to 0.5mm. BCN3D printers automatically correct the offsets when printing in Mirror/Duplication Modes.
However, this correction distorts the first layer of the model by repeating it as many time as needed. To avoid such distortion there are different options:
- Enable raft in BCN3D Cura: The offset will be corrected in the first layers of the raft, so the model won’t be affected by any Z offset.
- Install shims to mechanically correct the Z offset: Printing a raft takes time and spends material. For those users planning to use Mirror or Duplication modes frequently, it is highly recommended to install the shims when it is suggested during the Printer Calibration process.
In this video you find the steps to be taken to install the shims.