Hole Diameter Shrinkage Test

This is a simple test I made to determine how much filament shrinks, which was required for a project I'm working on requiring tight tolerances.  

Background:

I've found for some time that holes have greater shrinkage the smaller they are, even with the same filament and settings, which has driven me nuts for a long time.  I finally decided to make this test and chart the results to make future projects easier.  

You'll see in my final chart for Overture PLA Rock, that at the smallest diameter the shrinkage is around -0.35mm.  This increases almost logarithmically to around -0.08mm for a 5mm and larger diameter.  This effect is greater for other types of filaments, like PETG, and can vary depending on brand and settings.

Directions: 

Simply slice the .stl, print, and measure the hole diameters with a precision caliper and fill in the "Actual" column (I unfortunately can't upload excel sheets on Printables - see included photo of my tables and recreate) . Create a scatter plot and use the highlighted values in purple and blue as shown on my tables.

Notes: 
 

1. Caliper ID jaws are slightly offset which will throw-off measurements at the smallest diameters.  This can be somewhat mitigated by measuring at various angles, relative to the center, and taking an average.  Be cognizant of where the caliper jaws are measuring since this is a precision test!  
    
2. Measure each hole 2-3 times at least, in various positions, and take the average.  Due to seam positions and FDM inconsistencies (extrusion, temperature, filament density, etc), hole shapes will vary slightly.