Flexible Critter Maker

thingiverse

I like to print the flexible critters found on Thingiverse and wanted to create some of my own. To make it easier for me, and hopefully others, to create them, I created an OpenSCAD file (FlexiMaker.scad) containing a module that creates a flexible joint. (More accurately, it removes material from the critter model leaving the flexible joint.) If you just want to print my models then just use the STL files. Be careful when scaling the STL files because that also scales the joints. If you downscale the STL file, the resulting print may not be flexible due to the joints fusing. If you upscale the STL then the print might be too loose. So, the best way to scale the models is to open them in OpenSCAD and change the MODEL_SCALE_FACTOR value near the top of the file. You can also change the THICKNESS and JOINT_GAP. Larger JOINT_GAP values make the print looser while smaller ones make it less flexible. To create a new flexible critter, first start by searching the internet for royalty free clip art. Select an image in which the critter is solid black. If you can't find a solid black image, use a photo editor such as the GIMP to make the critter solid black. Then use Inkscape to convert the image into a DXF file. Search for "inkscape bitmap to dxf for openscad" for a tutorial such as this one: https://pressers.name/2013/09/13/extruding-silhouettes-3d-printing-inkscape-and-openscad/. There are a lot of tutorials out there but most don't include an important step to get the DXF file to work with OpenSCAD. Specifically you need to do Extensions -> Modify Path -> Flatten Beziers before exporting the file as DXF. Then, start OpenSCAD and open one of my files as a starting point. If the critter model can be cut in regular intervals, use FlexiBarracuda.scad. If there are pieces like legs or fins that you don't want to cut then use FlexiGator.scad. Save the file with a new name and change the name of the DXF file on the import line. Copy my FlexiMaker.scad file into the same directory as you OpenSCAD file. Start with MODEL_SCALE_FACTOR = 1 and adjust the MODEL_ORIGIN coordinate so that the left side of the critter touches the Y axis and the vertical center is on the X axis. Next, add a % character to the beginning of the line where the FlexJointRemoves module is called. This will show the material to be removed for the joints. (For some reason OpenSCAD takes a long time or sometimes locks up when you press F5 for a preview if you don't add the %.) For files based on FlexiBarracuda.scad modify the parameters for the loop encasing the FlexJointRemoves call to control where the joints are placed along the X axis. Also, modify the MODEL_Y_DIMENSION value so that the joints are cut all the way through the critter. For files based on FlexiGator modify the JOINT_SPECS array values near the top of the file. Each of the JOINT_SPECS elements is another small array. The first two values are the X and Y coordinates and the third is the Y dimension. FlexiManta.scad is the most complex example. Its JOINT_SPECS elements include a rotation parameter (between the X and Y coordinates and the joint height) to rotate the joint around the Z axis. (This is done at the wing tips, for example.) Once the joints look good, remove the % and hit F6 and save the STL file.