This is my penny press, which I designed and built for my Mechanical Design class at Olin College. I wanted to build something that was beyond the realm of my previous projects, and I wanted to use what I learned previously in Mechanics of Solids and Structures. I decided that this meant a machine with high forces involved, and a penny press had the added bonus that I was deforming metal. The machine now resides in the Milas Hall 1st floor foyer or the library near the door.
When a penny is inserted into the penny slot (A), it falls down to a rubber blocker (B) which depending on the position of the penny gate (C), either blocks the penny or lets it pass. Once the blocker lets the penny by, it falls down to the gate (C) which is turning synchronized with the dies (D). When the dies are in the correct position, the penny falls from the gate and into the dies. The dies have the design engraved into them, and pull the penny into them as they turn, crushing the penny and imprinting it with the design. Finally, then penny falls out of the dies, down a chute, and into the collection tray. Shown below is one side of each of the 4 two-sided designs.
To turn the dies a tremendous amount of torque is needed, since it takes nearly 5 tons of force to crush a penny. Starting from a 1 hp electric motor, the power is transmitted through a 18 part, 1190:1 reduction drive train. This consists of 10 sprockets, 5 chains, and 8 gears. It is supported by thick steel and aluminum plates to withstand the forces involved. All of the custom parts were made in the Olin machine shop, using the CNC mill, waterjet cutter, and the lathe. All together the machine weighs about 90 pounds, and can crush about 12 pennies a minute. The best way to get an idea of what this machine really is is to use it, so check it out next time you are at Olin and get a free souvenir.
Penny Press featured on Hack-A-Day
All CAD are SolidWorks files. See Links for SolidWorks viewing software. The two profile files are needed only to modify the frame extrusion profile. 02-00 is the top level assembly. A .zip file of all the CAD is available to save you clicking. It does not include the profile files.CAD.zip
80/20 1010 profile
Simplified 1010 profile
This is a full set of technical drawings. Some parts have to scale .dxf's that correspond to them, allowing you to upload them to a CNC machine to cut these parts. A .zip file of the whole package is available to save you clicking.Drawing Package.zip