# Designing for Accurate Hole Printing with a 3D Printer
We introduce the design methods necessary for ensuring accurate dimensions and positions when printing hole shapes with a 3D printer.
Designing in the shape of a drop or diamond instead of a full circle when producing prints with hole shapes, for more accurate dimensions, it is recommended to print them flat.
However, if other factors require you to print it upright, we recommend the following method
1. Water Drop Shape
- As shown in the picture below, if you print it standing up in a perfect circle, the overhang angle decreases as you go up in the height direction, causing sagging.
- Printout designed in the shape of a perfect circle Printout designed in the shape of a perfect circle
- To prevent this phenomenon, it is recommended to design in a water drop shape instead of a circular shape.
- The higher the Z-axis, the higher the overhang angle, preventing sagging.
- Printout designed in the shape of a water drop Printout designed in the shape of a water drop
2. Rhombus Shape
- If the boss shape is to be combined with other 3D prints, it is recommended to design it in a diamond shape.
- The diamond shape has an overhang angle of 45 degrees, so it can be printed on an inclined plane without sagging.
- Therefore, accurate assembly is possible as long as appropriate tolerances are given.
- Printout designed in the shape of a diamond Printout designed in the shape of a diamond
3. Considerations when Designing Tapping Holes
- When printing a tapping hole where a screw can be connected, if the thread is printed as is, supports may be created on the overhang of the thread, and if the diameter of the thread is too small, it may not be printed properly.
- The recommended method is to print a hole designed in the shape of a drop or diamond and then use a tool to tap it.
- What you need to be careful about at this time is the settings in the slicer.
- As you know, the inside of an FFF format 3D printer is filled according to the internal filling type.
- If tools are used on models printed with low density, the risk of damage increases.
- However, if you increase the density recklessly, more materials and time will be required, which will lower productivity.
- This problem can be solved by adjusting the wall thickness during slicer setup.
- Increasing the number of wall lines in the slicer’s custom settings increases the density around the hole, making threading more stable with the tool.
- For example, in the case of Cura, you can adjust Quality > Outer > Wall Thickness > Number of Wall Lines.
# When the number of wall lines is set to 2 (default)
# When the number of wall lines is set to 8
