[sudo-discuss] 3d printer solder paste dispensing at sudoroom using rpt2paste

[Jake]

last night at sudoroom i did some things to get solder paste flowing from the
TAZ 3 3d printer.

i brought in a compact air compressor and adjusted its power switch to click
off around 100 PSI (since it was failing to reach its design pressure in a
reasonable amount of time and we only need like 40-50PSI for solder paste)

i'm not sure if it's still working because it cut out apparently due to heat
the last time i was running it, but possibly just because of duty cycle.  It
needs a fitting installed into the outlet to plumb it to the solenoid.
Fittings are in the box behind the printer and there's teflon tape in the
"tape" box on the shelves in sudoroom.

i installed a three-port solenoid on the 3d printer which plugs in instead of
the extruder resistor / temperature sensor.  It contains a 47KΩ resistor to
simulate a thermistor (to avoid a fault code) and it wires the nozzle heater
wires to the three-port solenoid (which is rated at 24VDC matching the
printer's power supply)

I piped the 3-port solenoid to a syringe and mounted a syringe holder on the
print head assembly in a reasonable place.  A syringe of solder paste is in the
sudoroom fridge and can be used.  Needles of various sizes are in the cardboard
box behind the 3d printer.

the air compressor's outlet needs to be plumbed to the flexible black hose
going to the 3-port solenoid.  The solenoid needs to be mounted to the print
head (a twist-tie should work).

unfortunately the 3D printer's firmware seems to be cycling power to the nozzle
resistor when a temperature is selected, probably because of PID parameters, so
we will have to look for a set of commands (or modified firmware) to activate
the solenoid properly during the dispensing process.  This printer doesn't seem
to have wires for a print head fan, which is how we connected the solenoid in
past implementations of this setup.  There will need to be a script or
modification to rpt2pnp to issue the right commands for this setup.

as a reminder the software for creating g-code to dispense solder paste from
the .rpt file output of a KiCAD circuitboard project is here:

https://github.com/hzeller/rpt2paste

note that it's superseded by

https://github.com/hzeller/rpt2pnp

which may be newer.  the latter was confirmed to (apparently) correctly process
the .rpt file from the project we'll likely dispense solder paste onto first:

https://github.com/fitzdoingprojects/big_battery

i'll be gone for two weeks but if anyone wants to make progress on this project
please write back and i'll help as much as i can.

-jake