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Design Guidelines
First Cut Prototype uses multi-axis CNC machining to produce functional parts from solid blocks of real plastic.
Unlike additive processes that can create geometries of almost unimaginable (and, unfortunately, un-manufacturable) complexity, subtractive rapid prototyping is limited to shapes that can be cut out of a block of solid material using CNC milling machines.
Part Size
At this point in time the First Cut Prototype process uses three-axis CNC mills capable of producing parts within a 10 in. by 7 in. by 3 in. deep envelope. The maximum depth that can milled from either side of the part is 2 in.
Parts smaller than 0.25 in. by 0.25 in. by 0.25 in. are (really) hard to hold on to while machining.
Part Complexity
Fourth and fifth axis capabilities are in development at this time, so for the time being you should expect your FirstQuote® interactive quote to highlight any undercuts. It is not necessary (and not advised) to make any changes to your CAD model to reflect these changes unless specifically requested in your quote.
Sharp inside corners on a part will be radiused as a natural result of the CNC milling process. Your quote will highlight areas where these radii will occur.
Very small features, particularly if they are deep, may not be machinable. Recessed text should have a minimum stroke width of 0.020 in. The spacing between characters on raised text should be 0.020 in. or greater. Your quote will identify any issues with small features.
Wall Thickness
Unlike injection molding, CNC machining can produce very thick walls without sink or warp and there is no requirement that wall thicknesses be uniform.
Walls thinner than 0.020 in. typically do not survive the machining process.
Tolerances
Tolerances of +/- 0.005 in. are expected and generally achieved. There is no provision within the First Cut process to tweak any dimensions.
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