Lens Filter Step-Down Ring Adapter (Parametric)

grabcad

This is a parametric lens filter step-down ring. You can enter whatever inner or outer diameter you want, as well as the height and clearances. Requires FreeCAD .19 or higher and the Thread Profile workbench addon (get it from the built-in addon manager). In the tree, select "dd," and you should be able to enter the parameters. It takes a bit of time to recalculate the threads.Update v5: Now uses a better default clearance for both outer and inner threads. In particular, the outer threads needed a lot more. It's not tested universally for all diameters, but it should fit better. A lot will depend on how good your printer is with dimensional accuracy, and how you've tuned the filament. You can of course adjust the clearances to meet the needs of your printing material and printer. I recommend using at least .2 layer height and a .4 nozzle.