Volumetric flow rate and shrinkage compensation tests

Kill two birds with one stone for your new filament: maximize its print speed and ascertain its shrink rate. Do it all with less an hour of print time and no math required on your part.

What is this for?

These tests let you determine the maximum volumetric flow rate (and therefore the maximum print speed) that a filament can be printed at without failure, as well as how to calibrate the dimensions of your filament to get dimensionally accurate parts.

The tests leverage the slicer calculations itself to discover what the limits for your filament are.  The file uses settings varying by height to try and induce print failure.

You'll need Vernier calipers (or a decently accurate ruler) to make this test worth your while.  You'll likely need PrusaSlicer, although other compatible slicers might work (if the settings in the 3MF file translate properly to its own settings).

Tests done for one printer (or one nozzle slice) might not translate for other printers (or nozzle slices).  So be prepared to repeat the tests depending on your printer and its configuration.

How to use this

Set everything up:

1. Open up the 3MF file in PrusaSlicer.
2. Select your printer with the appropriate nozzle size.
   1. If prompted, transfer all the settings minus the printer and filament settings to the selected profile.
   2. Double-check the following settings in the Print Settings pane:
      1. Speed for perimeters, small perimeters and external perimeters is set to 250 mm/s or more.
      2. If your printer is extremely capable, double or triple those values.
   3. Double-check that none of the selected filament settings deviate from the baseline.
3. Select the filament profile you want to calibrate (or create a new one based on an existing profile).
   1. If prompted, discard all custom filament settings.
4. Within the Filaments pane:
   1. Set your filament's Shrinkage XY compensation settings to 0% (this setting is in the advanced section).
   2. Set the Max volumetric speed to something absurd like 50 mm³/s (on the same section).

Preview the build plate, then switch the Legend (enable it if hidden) to actual volumetric flow rate.  You should see something like this (note the absurd max volumetric flow rate):

Dispatch the print.  Let it print until it either fails or you begin to see defects in the serpentine model on the middle of the build plate.

Detach both models, and let the L shape model cool down for an hour or so.

Download and unzip the spreadsheet provided with this model.  Open it up in LibreOffice or Excel.

Measure the length of both sides of the L, and average them.  Input that average in the spreadsheet (tab xy compensation).  The value you get under the Xy compensation column is what you shall set in your filament's Shrinkage XY compensation.

Now measure (using your calipers) the height of the serpentine from the bottom until the first print defect began to show up.  That height corresponds to one of the slabs in the model which has a specific speed limit.

Now that you know which height the serpentine failed at, do the following:

• Switch to the preview of the build plate once again and make sure it is sliced.
• Enable one-layer mode (orange padlock below the vertical height selector) on the preview pane).  The padlock should turn from orange white when clicked, and the preview will show only a single extrusion line.
• Using the vertical height scrollbar, select the layer height you measured at which the model began to fail printing. The tooltip pointing to the knob in the height selector will display the height in millimeters and the layer number in parentheses.
• Using the horizontal tool path scrollbar, move the tool onscreen to the end of the longest, fastest  segment of the serpentine (that segment should be colored the reddest at your selected layer height).  You can move the tool step by step using the mouse wheel.
• Pop up the Properties pane floating right above the horizontal tool path scrollbar.

You should see something like this right before popping up the properties pane:

Once you pop the properties pane, it should display something like this:

Note the shape of the curve of the actual speed profile (it's an inverted U, rather than a slope).  This is an indicator that you got the fastest-accelerating segment of the whole model, at the highest speed.  If you don't see an inverted U, scroll around step by step (using your mousewheel or touchpad scroll gesture) until you identify the absolute highest speed movement.  Once you find it, write down the Volumetric flow rate shown on that pane.

Enter that volumetric flow rate as the maximum volumetric flow rate for your filament (under the Filaments tab).  Now would also be a good time to adjust other settings like the price per spool, or the weight of the spool.

Save your filament's settings as a profile (either a new one or overwriting the existing one you created).

Congratulations, your filament is now calibrated both for dimensional accuracy and for maximum speed without defects!

Added dimensional test and actual speed tests using setting overrides slab by slab.