Samiad Designs

keep it simple

matterQ Real Time Estimates

1st December 2013

This week I added real time remaining estimates to matterQ. A problem I've had for a while is having no real idea of how long a print is going to take to complete. Slicers like Cura give an estimated print time but this is often wildly inaccurate when actually printing.

Part of the problem is the way firmwares like Marlin will interpret gcode loosely suggestively rather than literally so the slicer has little idea about how long a set of instructions will actually take to execute. With my Ultimaker 1 running Marlin I often get time estimates from Cura that are less than half the time it actually takes to print.

In matterQ I have taken a very different approach to time estimates. When the job starts the current time is recorded. As matterQ already tracks filament extruded at each line of gcode we can look at how long it has really taken to print all of the filament so far at any point in the print. We don't try to calculate print time from the gcode, we just measure real print time and extrapolate.

This does get distorted early on in the print when printing is typically much slower so the ETA will start out too high but then come down and stabilise quite quickly.

This change is currently just in the matterQ git head and not in any released image. Existing matterQ installations can be updated to the git HEAD by following the instructions on the wiki.