If you’ve ever printed a multi-color or multi-material model, you’ve probably noticed a small tower appear next to your print. That’s the prime tower. It might seem like a waste of space and filament, but it is essential in preparing the nozzle pressure before the hotend resumes printing.
Without the prime tower, your model may have gaps, blobs, or weak spots if the nozzle begins printing without enough pressure.
Here’s everything you need to know.
What Is a Prime Tower?
A prime tower is a small structure printed beside your model during multi-color or multi-material prints. Its primary purpose is to “prime” the nozzle by allowing it to build pressure in the nozzle before starting a layer. It’s essential between filament swaps because the nozzle pressure dissipates with every color change.
Without priming the nozzle, the hot end may not have adequate pressure for printing. Without adequate nozzle pressure, you may get gaps, blobs, or weak walls.
As a secondary function, it acts like a purging station. The tower gives the nozzle more time to purge old filaments and prevent color bleeding.
Say you’re printing with red and white filament. When switching from red to white, a little red might still be in the nozzle. That leftover red can mix into your white layer, creating a pink streak or little white specks. The prime tower handles that cleanup for you, so transitions stay clean.
Can You Print Without a Prime Tower?
You can still get good results without a prime tower and save filament waste during your multi-color prints. Although I’ve successfully printed multi-color prints without a prime tower, sometimes I’ll find issues with gaps, weak walls, and blobs on the surface of the prints.
If you don’t set the flushing volume correctly, you’ll also find issues with dirty transitions caused by the previous color bleeding during filament transitions. Color bleeding leads to streaks, patchy layers, or dots of color, especially with high-contrast colors like black and white.
Skipping the tower creates even more risk with multi-extruder setups, as the nozzle needs more pressure to prime when it goes from not in use to printing.
Slicer Settings in Popular Slicers
I almost always use the default slicer settings. But if you’re looking to fine-tune your nozzle pressure, here’s a quick look at the prime tower settings in three popular slicers: Bambu Studio, PrusaSlicer, and Ultimaker Cura.
Bambu Studio
Bambu Studio gives you detailed control over your Prime Tower. You can find these options in the Process > Other > Prime Tower section:
- Enable: Toggles the prime tower on or off.
- Width: Set how wide the tower is along the X-axis.
- Prime Volume: Controls how much filament your printer purges into the tower at each color change. Increase this if you see color contamination or underextrusion at layer starts. Increase this value if you see residual colors or under-extrusion.
- Brim: Add a brim for better adhesion. Brims are especially beneficial for taller towers.
PrusaSlicer
PrusaSlicer calls it a Wipe Tower and keeps it simple with just two options and auto calculations for the rest. You’ll find these settings in Print settings > Multiple Extruders > Wipe tower:
- Enable: Turn it on when printing with multiple filaments.
- Width: Adjust the tower’s width along the X-axis. A larger width helps with bed adhesion, purges more filament, and ensures adequate nozzle pressure.
UltiMaker Cura
Cura offers more granular control under the Custom mode:
- Enable: Activates the prime tower.
- Prime Tower Size: Sets the overall size of the tower in the X/Y direction.
- Prime Tower Minimum Volume: Defines the minimum volume of filament to deposit in the prime tower.
- Prime Tower X/Y Position: Allows you to choose the location of the prime tower from the origin point of the build plate.
- Wipe Inactive Nozzle on Prime Tower: After printing, wipe the inactive nozzle on the prime tower to reduce the chance of oozing.
- Prime Tower Brim: Adds a brim for extra build plate adhesion on the bed.
Final Thoughts
Although the prime tower might seem like a waste of filament, it plays a big part in the print quality of multi-color and multi-material printing. Although it adds a bit of print time and uses more filament, prime towers greatly enhance print quality and reduce color bleeding.
Think of it as an insurance policy for your print. It keeps your layers clean, your transitions sharp, and your print quality high.
If you’re printing with multiple colors or materials, leave it on. You’ll save yourself a lot of frustration.
