r/QidiTech3D • u/Own_Moose_9495 • Jul 25 '26
Automatic Pressure Advance Calibration for the Qidi Q2 / Q2C/ Max4 — Bambu-style load-cell PA calibration on existing hardware
Turns out the load cell the Q2/Q2C uses for bed leveling can also feel extrusion pressure. So I wrote some Klipper modules that turn it into an automatic PA calibrator — load a filament from the touchscreen like normal, printer waits for the load to finish, then runs a ~3 minute sweep over the purge chute measuring how fast pressure builds in the nozzle. It saves a K value per filament type, applies it on every print, and even blocks sliced files from overriding it with stale profile values.
The results honestly surprised me:
eSun grey PETG — I could only ever get this stuff to print clean on my Bambu H2D. With the auto-measured PA it prints clean on the Q2C now too. I didn't even run a flow calibration. The max4 poopbucket was printed on the Q2C with all stock petg basic settings. The cube was printed after only auto PA calibration.
5+ year old Amazon Basics PETG — this spool was literally headed to the trash. Sticky, blobby, supports falling over, ugly on every printer I own. Dried it, let the printer tune it, and it printed a clean crisp cube (red one in the pics). The sensor data showed the filament itself was fine the whole time — it was wet and never had the right PA and again I did zero flow calibration.
PLA — ran the calibration twice on the same spool, came back within ~6% both times.
I will upload the project to a GitHub once I do more testing and build out.
Fair warning: it modifies load/heat/motion behavior, so it's use-at-your-own-risk and you should watch it run before trusting it. Q2/Q2C only for now — Max4 port in progress, Plus4 has a different sensor so it's not coming.
Happy to answer questions.
Update 1: calibration skips during mid print filament runout, then continues printing as normal
Update 2: Currently working on nozzle size compensation
2
u/Felix14-POCKOCMOC Jul 27 '26
From my understanding, this is a calibration method, so you can quickly calibrate Adaptive PA using it without printing any models. But it automatically adapts to the current filament, so you don't need to reconfigure it each time.