Bridging is a term used when you are printing a flat horizontal part of the model in mid-air. Although the use of a support structure may be a solution, there are other more functional solutions.
This guide will try to explain which settings are recommended to achieve the best results for bridge-like objects.
First of all, consider the orientation of the model on the print bed. In some cases it is sufficient to rotate the model, so that there are fewer parts subject to cantilevering.
If you want to print a bridge for example, you will find that the overhangs are shorter if you rotate the model
To ensure that the plastic parts on the bottom layer of the bridge adhere well to the pillars, it is important not to print too fast. A high printing speed will lead to poor adhesion of the plastic to the pillar (the nozzle may drag it) and material may fall.
Using a lower printing speed the plastic will have more time to adhere properly to the pillars, and will have good adhesion. For PLA you could for example try to decrease the print speed to 20-30 mm/s, instead of using the default 50 mm/s.
In addition to the printing speed, temperature is also an essential factor in creating bridges without inaccuracies. In general, a lower temperature works better. The reason is that the material is less liquid and more difficult to string at a lower temperature. You should not fall into the trap of too low a temperature however: printing below the optimum temperatures normally leads to under-extrusion. A temperature between 180° and 200° should be fine for PLA, unlike the normal temperature, which ranges from 190° to 210°.
The importance of ventilation
In addition, the cooling of the material is another important factor. Ensuring that the printhead fans run at full speed is critical to hardening the plastic as quickly as possible.
If the bridge we want to print is not too far from the plane of the print bed, it could also contribute to a small decrease in the temperature of the plate. Due to the heat of the heated bed, the plastic may take longer to harden, creating annoying defects or smudges.
To summarize, to try to print bridges or similar objects without using support structures you can:
- change the orientation of the object itself
- exposing the least number of everhanging parts
- slow down the printing
- lower the extrusion and the heated plate temperature
Now that you have all the necessary information, it’s time to print something good!
BEST FILAMENTS FOR BRIDGING: