Changing Pressure Support Guide

The pressure you supply to an extruder is one of the most important parameters in pneumatic extrusion bioprinting. As such, you’ll probably want to change your pressure settings a great deal as you optimize your prints and switch between projects. Below, we discuss different pressure change circumstances and how to achieve them.

I want to change the pressure before I start printing.

You can do this from the Extruder Section of the software. For an in-depth look at this section check out the Extruder Section of our article Allevi Bioprint Online. When sending a new set pressure, make sure to wait for the pressure to update in the ‘Current’ pressure window before proceeding with a print.

I want to program different, simultaneous pressures for coaxial printing.

Check out our Coaxial Printing Protocol for instructions on activating simultaneous pressures.

I want to test different pressure levels in a single print.

  • First, pause the print using the pause button in the status bar of the software.
  • Next, navigate to the Extruder section of the software. Some settings will be unavailable but the pressure settings can be altered during the pause.
  • Set your new pressure value in the set window and send the command.
  • Wait for the ‘Current’ window to show the new, correct pressure value.
  • Resume the print.

I want to control pressure during a print without pausing.

Controlling pressure without pausing requires you to edit your gcode file to include the pressure control commands.

  1. Open your gcode file in your preferred text editor.
  2. Wherever you want to change the pressure, add the following code snippet:
M107 T{active extruder} ; this stops extrusion
C1 S{target pressure} ; this sets pressure to target
G4 S{seconds} ; this waits for the set time*
M106 T{active extruder} ; this resumes extrusion
  1. Save your gcode file and print!

*Note: If the difference between target pressure and current pressure is large, you will want to include the G4 dwell command. Otherwise, you may be able to ignore it.

Reference: Allevi Gcode Documentation

While generally similar to the gcode used to control simultaneous extrusion in coaxial printing, the key difference is that your T commands and P commands should reference the extruder you are actively printing with rather than the auxiliary extruder used in coaxial printing. Also, note that unlike coaxial printing, you can use this technique with the Allevi 1.

Do I need to change pressure levels from the air compressor?

Nope! The pneumatic system in the printer can easily regulate the pressure going to the extruders according to the settings you program from the software. Therefore, you can set up the air compressor to supply the minimum 120 PSI and let it go. In fact, we encourage you not to change the supplied pressure from the air compressor.

If you have any further questions, contact the Allevi Support Team.

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