Flow Rate Calibration 2nd step always prints pieces from 0 to -9

Bambu Lab Software Bambu Studio
1

I am in Bambu Studio 2.5.0.66 on Linux. I am using a 3DJake silver PCTG filament with not so optimal results. Through the Bambu Studio Training Courses I learned about he filament calibration. Run first level. Checked the printed pieces and decided that part “5” is the best. Run fine calibration, but instead of printing 0 to +9, it printed 0 to -9.

Today I went there again. Selected “Fine Callibration based on flow rate”, changed the already entered “0.95” to “1.05” (since my best piece was “5” and not “-5”) and again it printed pieces from 0 to -9.

The json file that it has created under “/.config/BambuStudio/user/XXXX/filament/3DJake PCTG Flow Rate Calibrated.json look like this:

{
    "filament_extruder_variant": [
        "Direct Drive Standard",
        "Direct Drive High Flow"
    ],
    "filament_flow_ratio": [
        "0.9765",
        "nil"
    ],
    "filament_settings_id": [
        "3DJake PCTG Flow Rate Calibrated"
    ],
    "from": "User",
    "inherits": "Generic PCTG @BBL P2S",
    "name": "3DJake PCTG Flow Rate Calibrated",
    "version": "2.5.0.14"
}

Did anyone also run into this? Any tips?

2

I think it has been 0 to -9 since I can remember. Why should it be 0 to +9?

I don’t understand why it isn’t -5 to +5. That would make more sense to me than both of those options.

3

0 to +9 or 0 to -9 doesn’t matter; the test designer had to choose one direction before creating the second-pass test. If the optimal result is at +7, testing +5 to -5 would not find it.

The first pass only narrows the testing range. Then the second pass tests flow rates in smaller steps in a range between too high and too low.

I don’t choose the best result from the first pass. I choose the first result higher than the smoothest, the one that is clearly over-extruded. Then the second pass reduces flow in small steps to test between slightly too much flow and slightly too little.

I made a simple spreadsheet to help me see how my choice affects the rates to be tested. Changing the yellow cells updates the rates to be tested.

image
image472×457 8.4 KB

Rename to remove the “.3mf” extension.

Flow calibration calculator.xlsx.3mf (7.5 KB)

I don’t think using the third decimal place makes a significant difference in flow, but I don’t round it; I keep it because it indicates that it is a calibrated flow rate.

I usually delete some samples before printing the first pass. Starting with a Generic profile, I’ve never had a filament that produced a good result at ±20, or even ±15.

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4

Thanks a lot for sharing this. I’ll retry it. When using the flow from BambuStudio it sends directly to the printer, without letting me edit the samples.

5

Enable Develop mode in Preferences to enable the manual Calibration menu at the top of Studio.
Then, unneeded samples can be deleted.

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