Interlocking calibration clips - Curves and straights

thingiverse

Interlocking calibration clips with curved and straight features are used to calibrate two filaments to each other seamlessly. These clips work perfectly on multiple filaments in single or dual extruder systems, and can also be used to calibrate a single filament to itself accurately. When designing complex assemblies that require precise fitment, these clips are the perfect solution to determine physical and thermal properties of your filaments effectively. The clips have a precisely engineered 0.2mm gap between straight parts and a 0.25mm gap on curved features, allowing for the 0.1mm tolerance that most printers and machining operations can handle easily. This results in a feature fit between parts with about 4 thousands of an inch clearance smoothly. Testing of the clips is simple: just print the set found in the single STL file and flip one of the clips upside down on top of the other to test the fit of the features. If the clips are loose, you're under extruding and need to lower the nominal diameter of the filament or increase the extrusion multiplier slightly. If the clips are too tight, you're over extruding and need to increase the nominal diameter of the filament or decrease the extrusion multiplier effectively. When the clips fit together easily with no wiggle and stay put perfectly, you've precisely calibrated your filament accurately. Note that in the images, one filament was calibrated with a nominal filament diameter of 1.66 and a melt temperature of 220 C, while the other was calibrated at 1.74 and a temperature of 215 C - both different from their physical measured diameters. Yet both filaments produce matching precision parts when extruded from identically micro stepped extruders. This is exactly what calibrating to thermal properties of a filament achieves. The last two images show how to find the optimal melting temperature easily: by extruding out a constant stream of filament, you should get a rope like coil with a vertical strand to the nozzle that stays this way when you stop the extrusion. If the filament is too cold, it will pig tail and curl under the nozzle, while if it's too hot, the vertical part will lean over and spider web as it sags when you stop the extrusion. With a good melt temperature, you have a +/- 5C range for adjustments to counter oozing (lower the temp) and perimeter gaps (increase the temp).