Recently, we received an RFQ for 600pcs custom DuPont POM-H parts. While the 3D model looked straightforward, a quick DFM (Design for Manufacturability) review of the 2D drawing caught my attention. Per the drawing’s title block, general tolerances were set as:

🔹 X.XX = ±0.05 mm

The drawing specified an M5 thread depth of 10.00 mm and a pilot hole depth of 12.40 mm. Because of the two decimal places, this automatically defaulted to a tight ±0.05 mm tolerance on blind hole and thread depth!

I immediately checked with our shop floor technicians. Could we achieve ±0.05 mm on thread depth? Yes. Would it drive up machining, tooling wear, and inspection costs unnecessarily? Absolutely. In most non-critical assemblies, thread depth tolerancing is much more forgiving (e.g., ±0.2 mm). It was very likely a simple CAD drafting default habit—writing "10.00" instead of "10". Instead of just quoting a high price to cover the strict inspection, I sent a technical query (DFM feedback) to the client’s engineering team, suggesting a relaxation to ±0.2 mm.

Two days later, the client confirmed: "Yes, ±0.2 mm is completely fine." The Takeaway: A good manufacturing partner doesn't just quote what’s on paper. We look out for over-engineering and help engineers & buyers optimize production costs.

How often do default title block tolerances impact your component costs? Let’s connect and discuss precision machining DFM!

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Sometimes, cost reduction starts in the design stage—not the price negotiation.