Cannot get Auto-cooling to work as detailed.

[sloped-soarer]

Hi.
Preflight seems okay so far. However I have a problem with Auto cooling.
Auto cooling, Uniform cooling. If I set the minimum and maximum fan speeds and the "Enable fan if layer print time is below" and "Slow down if layer print time is below" the summary of what should happen in the Enable section is correct.
However when I preview layer time and fan speed this does correlate to what should happen.

Anyone else notice something weird here along with the linear interpolation of fan speed.

[oozebot]

Please provide a 3mf project with all your settings saved within it for review. You can post it here by renaming it to *.txt

Thanks

[sloped-soarer]

preflight_cone_3mf.txt

[oozebot]

Thank you for reporting this. Auto cooling is doing it's job correctly: Your nose cone is a single wall at 80 mm/s, and the time it actually takes to print a layer, measured the way the cooling code measures it (distance divided by feedrate), is about 4.4 seconds at the base. That sits just above your 4 second "slow down" threshold, so the fan lands within a percent of your 20% maximum, and from about mid-height the layers get stretched to 4 seconds as the cone narrows. All of that matches the description in the Cooling page.

What did not match was the layer time the preview was showing you: around 15 seconds for those same layers, and 3h 14m for the whole print. That number comes from the time estimator, which had a bug. The formula that decides how fast the extruder can go around a corner was using the wrong angle, so every one of the small facets that make up a curved wall was being treated like a much sharper corner than it is. On a curved thin-wall part like yours that inflated the estimate by roughly 3x, and it made the preview's layer times disagree with the cooling, which was using the real time. So you were reading "15 s, fan should be 10%" while the cooling was correctly reading "4.4 s, fan at 20%".

This is fixed for the upcoming v1.4 release. Your project now estimates 1h 53m instead of 3h 14m, and the layer times in the preview drop to around 8 seconds, which should be much closer to reality. The fan and speed output of your G-code was already correct and did not change.