Continuous rotary to intermittent rotary via a Reuleaux triangle

thingiverse

This is basically a re-design for 3D printing of the mechanism posted on GrabCad here: https://grabcad.com/library/reuleaux-triangle-intermittent-mechanism-1 Based on a (modified) Reuleaux triangle (see: https://en.wikipedia.org/wiki/Reuleaux_triangle#Rotation_within_a_square) the mechanism converts continues rotary motion to intermittent rotary motion. The Reuleaux triangle providing movement to and from the gear-to-be-rotated and the rotation of that gear. Very neat, I reckon. Designed in Moment of Inspiration (Moi), simulated in SimLab Composer Mechanical and printed in Diamond Age PLA on an Ultimaker original. Note that included in the stl files is an optional part Reuleaux rotor spacer. You may not need to use this if you can print everything flat enough. I found that I could fully tighten all 'keeper' screws, but not the screws retaining the handle lever. In the photos and video I've spaced the handle lever out with stainless steels washers, but they are fiddly to fit so I subsequently designed the aforementioned spacer. Note also that the posted stl files differ slightly from the model that I printed. I've changed the hub keeper set up from 3 screws to one screw, and added 3 more holes in the base to accommodate a wider range of rubber bands. Hardware required: 1 longish rubber band 3mm x 10mm long button head cap screws. At least 11 with a maximum of 16. A video of the model 'in action' is here: https://youtu.be/_lvGsT3ATXw A simulation is here: https://youtu.be/HkxusRPVYAA A 3D pdf file in which you can rotate the model to any attitude and then run it is included in the files. Print Settings Printer Brand: Ultimaker Printer: Ultimaker Original Rafts: No Supports: No Resolution: generally 0.2mm see Misc. Notes Infill: 30% Notes: Material: I used Diamond Age PLA. If you need the Reuleaux rotor spacer, which is only 0.5mm thick as designed, 0.1mm resolution is appropriate otherwise 0.2mm is, I think, fine. Generally for models of mechanisms, such as this, I use 1.2mm wall section everywhere. For the larger parts I strongly recommend a good sized brim to minimise warping. NOTE. I have NOT oriented the parts for printing. Some will have a suitable orientation, but most do NOT. Post-Printing Firstly the normal cleaning up. I use a tapered reamer to clear excess from all holes. For holes in which parts rotate I bring the holes to size with the appropriately sized hand reamer. Note that the hole in the handle lever that accepts the handle stem should NOT be reamed out. The handle stem should be a tap fit into the handle lever. All parts should rotate freely. Finally, the rubber band. You should aim to have the rubber band hardly stretched at all when the pawl is engaged in the gear. Use as long a rubber band as possible and screw a 3mm x 10mm (or a bit longer) screw into the appropriate hole.