correlate PID error and filament flow to detect filament breaks.

[solmetricchris]

The PID controlled temperature has an output which should strongly correlate with the amount of heating necessary to keep the correct melting point. And the amount of heat necessary should correlate with the flow rate of the material.

It should be possible to detect filament breakage by noticing that the heat required is LOWER than the requested filament speed (which is wrong since the while the filament feeder is running, no filament is moving ) would normally indicate.

Detection of this error condition could bring a print job to a pause and prevent an ugly mess on the table and possible damage to the print head.

[daid]

In theory yes, however, in practice, there are a lot of variances and other external factors that influence this. As it's not just material flow that influence the PID, it's also retractions, external temperature, actual heater strength, drafts, head movements, fan speed, etc...