Flow Measurement and Calibration Jig

I needed a more convenient way to measure the length of extruded filament, e.g., for calibrating the extruder, or estimating your actual flow rate according to Ellis' printing guide. So I made this small jig. It's a parametric model, so you could make a longer one, or of different sized holes if your Bowden couplers have a smaller thread. The holes for the Bowden couplers are a bit deeper, so you can thread them in until they are exactly 100 mm apart. The optional internal Bowden tube section constrains the filament to keep it straight.

Just mark the filament on the incoming end, extrude 100 mm of filament and measure the exact length extruded. 

The model includes a scale on the top, which I painted with a sharpie for contrast. A more elegant option would be to do a filament swap before for the top face.

Update V2

• Cleaned up the code a bit for the OpenSCAD Customizer
• Added the possibility for “special” scale lines, e.g., to have a longer 120 mm calibrator with a special 100 mm line.

Update V3

• Fixed the Filament channel size
• Added a channel for a Bowden tube, that can be fixed with small zip-ties. This constrains the filament and avoids the bends visible in the video.