pneumatic extruder clamp, carriage adapter, and solenoid bracket

thingiverse

Pneumatic extrusion printing is incredibly straightforward on nearly any open source 3D printer. All you need to do is create this pneumatic extruder and set up post-processing scripts that turn on an output - this output opens a valve and applies pressurized air to dispense material. Pressure The toughest part may be finding a consistent source of high-pressure air. If you have an air compressor/tank or house air at a lab/shop, it will work best. I'm also working on adapting a 2L soda bottle; these can hold up to 100 psi! (50psi safely) even still, use at your own risk. You should not need more than 30 psi, and we'll use a 30psi max regulator to the pressure we need (only ~10-15psi). Again, the flow is: pressure source/regulator, solenoid to control flow, dispensing syringe. Electronics You do not use the existing extruder motor, but you do need an extra output like a controllable fan that can handle ~500mA (some fans are only 20-50mA). Alternatively, you can use the extruder heater output, but you will not be able to heat and control a nozzle tip and may have to make firmware modifications to make it work. You'll have to ensure a safety feature is disabled that kills the printer if the heater is on but an increase in temperature is not detected. This can be hazardous for (hot) plastic printing though, so use at your own risk! Some printers don't have this enabled by default, so for example, the Monoprice Mini does not have an extra fan or open-source firmware, but can use the extruder with this setup. Toolpath To automate the use of these outputs, you'll have to install python and point your slicer to scripts that add lines of code (only a semicolon between scripts with the full path). One script turns the solenoid ON AFTER an unretraction (make sure retraction is >0 in your slic3r) and unretraction should only happen when you want to start dispensing. Another script turns the solenoid OFF BEFORE a retraction to stop dispensing (if it stops AFTER the retraction, it will leave a blob at the end). Then, connect one alligator clip to the bed and one to the needle, and use those two wires in place of a typical mechanical endstop switch. Bed Leveling I highly recommend using auto-bed leveling with a conductive nozzle and metal bed to eliminate variability measuring line width. I may post this as a separate thing with details about how to enable it in the firmware. The physical setup is easy - fix a 3/16" thick 8x8" aluminum sheet from mcmaster-carr to the bed with binder clips.