The "Decimal Point Tax": How Smarter Tolerancing and Onshape MBD Can Slash Your CNC Costs by 35%
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In the world of hardware startups, there is a silent killer lurking within your CAD files. It isn’t a flaw in the physics of your design, nor is it a lack of market fit. It is much more subtle: It is the "Decimal Point Tax." Recently, I stepped in to assist a small engineering startup that was on the verge of a financial crisis. Their initial CNC quotes for a relatively simple batch of aluminium parts had come back nearly double their projected budget. Their first instinct was that the machine shops were price-gouging. My instinct? The drawing was the problem. The High Cost of Fear-Based Design When I opened their manufacturing package, the issue was immediately apparent. Because their CAD software was set to a "standard" precision default, every non-critical feature on the part carried a tolerance of $\pm 0.05 \text{ mm}$ . To a designer sitting behind a screen, $\pm 0.05 \text{ mm}$ feels like a "safe" number. To a CNC machinist, that number is a mandat...