How to CNC machine a Rapid Prototype
Thin-walled housing for a docking station
Maycom Audio Systems in the Netherlands is an innovative manufacturer of digital audio equipment. The company has an international reputation for it's custom-made radio automation systems for broadcasting stations. This project concerns a new product: the Maycom HandHeld recorder: a portable recorder meant for on-site audio recordings of a professional quality. The product exists of two separate parts: the handheld itself and it's docking station, including the re-charger, an (additional) loudspeaker and the external interfaces. This Gallery page concerns a prototype of the docking station that has been created using DeskProto.
The Maycom HandHeld Recorder in it's docking station.
In addition to all functional requirements, an important requirement for this product was a "stylish design" to make the product highly appealing to potential users. For this aim an external design bureau was contracted: Spark Design. One of the design tools used by this bureau is Rapid Prototyping, and in various stages of the design process prototypes have been created. First (rough) concept models, later more detailed, and also functioning models.
While concept models and presentation models can be solid (styling block models), a functional prototype needs thin-walled parts of the housing, in which all inner parts can be assembled. Creating a styling block model using DeskProto is easy, as in many cases the total geometry can be machined from one side (no undercuts as the project will be injection-moulded later). A thin-walled model however, needs to be machined from two sides. DeskProto makes this easy as well by using the Two Sided Milling Wizard.
The second side of the model is being roughed now. You can clearly see that the inside of what appears to be a solid block, has been made hollow while machining the first side. Both sides are perfectly aligned, thanks to the ruler shown in front and the DeskProto Two-Sided Milling Wizard.
The Two-Sided Milling Wizard defines a stock (block of material) to be used that is larger than the model, to leave a frame of material around the model for clamping the block down. On the left and on the right there is room for the clamps. To keep the model connected to this frame four "Support Blocks" or Bridges are created by the Wizard. A ruler on the machine's working table, and a reference plane, machined on the back of the model when the first side is finished, make sure that after turning the block upside-down the second side can be machined without changing the tool zero point. This is all explained step-by-step by the Wizard.
Extra detailing operation with a small tool (diameter 0.8 mm - which is about 0.03"), to create the speaker-slits which are important both for functional testing and for the product's appearance.
The Wizard generates a Roughing operation and a Finishing operation for each side of the model. After that it is easy to add extra operations as required, using different cutters. Operations for instance with a Ball-nose cutter for a smooth surface and an end-mill for sharp inner corners, and extra detailing operations with smaller tools for selected areas.
The resulting thin-walled model of the docking station's front cover.
The model is shown as it came from the milling machine: including the frame around the model and the four support blocks. These have to be removed manually, followed by some sanding to remove their marks.