This page is a continuation of the mechanism project; this time we will be creating and 3D printing a handle to attach to our pinion gear and incorporating changes that were suggested during a design review.
Creating Handle:
The design inspiration for the handle I will be creating was for it to attach similarly to a rivet, so I will be making a back piece that goes through our pinion gear and then a handle for the top piece that will be force-pressed onto the back piece.
To make the back piece, I made a sketch of half of a center-cut view so that I could revolve it around the center axis to make the part.
I made the handle in the same way but made it as a new external component so I could reference the back piece while making it.
3D Printing:
To 3D print the parts, first they both must be exported as .stl files. To do this, go to File > Export > Change type to .stl. Now import your stl files into your 3D printer software, I will be using 3DPrinterOS. Once your files are imported, align them on the printer bed and adjust your print settings. Here are mine: 0.15mm layer height, 1.5mm wall thickness, 40% infill density, 215°C print temperature, 60°C bed temperature, and auto-generated supports.
Improving Overall Design:
During a design review of the mechanism, it was pointed out that adding supports on the edges of the backing to hold the rack at its extended positions would prevent the rack from being pulled down by gravity which would sometimes cause the gears to seize up. This will be fixed by adding two rollers on the outsides of the backing. For the rollers, I have two screws that are 0.16″ in diameter so I made 1″ circles with a 0.16″ hole in the middle. I also want to find out what size hole I need to cut into the backing to be able to screw the screws in so I made holes ranging from 0.135″ to 0.150″.
After laser-cutting, the sliders seem like they will work well and the screw fits best in the 0.15″ hole. Now I am going to edit the backing CAD file to have holes for the sliders to screw into and laser-cut the holes into the backing. Upon adding the holes to the backing I realized my measurements were slightly off and the rollers were too high, so I cut out new rollers that are 0.75″ which worked.
Final Assembly:
Once the handle had printed I realized that the rivet design was not going to work but the handle turned out nice and was able to be superglued onto the pinion gear. After adding the handle and slider supports to the design this is how it turned out:
