Tool to Help Scale Model Size

thingiverse

If you're accustomed to scaling models down to your desired dimensions, there's probably little here that escapes your awareness. The purpose of the printed tool or paper with a measured line is to scale a three-dimensional rendered image to a known size that can be measured using a caliper or compared to a real object for size comparison. It's crucial to adjust the display so it's in parallel projection mode, often named something else but avoid the perspective mode where grid lines are closer together at the back edge of the XY display plane. When making measurements from the display, ensure that the surface measured is parallel to the front edge of the screen. Measurements on an isometric view of any surface other than that parallel to the edge of the screen aren't feasible. For small angles, though, being slightly off-square won't make a significant difference since this method doesn't have high accuracy beyond the original CAD drawing. I typically use this tool to scale a model displayed in Repetier Host (or Cura, or Sketchup, or other) so it's displayed at its actual real-life size. When the display scale is accurate, you can make measurements on the display of the model to determine its printed size. In the case of a cup or vessel, you can section the model, measure its interior dimensions, and calculate its volume. The tool here measures 40 and 50 mm along the outer edges. The interior edges are 20 and 30 mm long. The outside long dimension is 60 mm, and the width of the parallel ends is 10 mm. The photos show a whole model and a sectioned model in Repetier Host's parallel projection mode, adjusted to match the 4 mm side. The resulting model is then life-size on the display screen, as long as you don't cause the display program to zoom to fit the screen.