Marco Mascolo
Founder & CEO
Jul 8, 2026
TL;DR
Auto-dimensioning tools put every number on the page. That is not a drawing, it is a data dump. Over-dimensioning buries the critical features, inflates manufacturing quotes, creates callouts an inspector cannot measure, and stacks tolerance until a feature drifts off the part.
The fix is to dimension to function: include only what is needed to make and inspect the part, dimension from datums rather than chaining, and let general tolerances cover the rest. This guide explains what is wrong with dimensioning everything, why over-dimensioning costs real money, what a non-measurable dimension is, and how to dimension a drawing to function the way an experienced detailer would.
By the numbers
Reliance on 2D modeling costs US manufacturers about $5.2 billion a year, per NIST (Advanced Manufacturing Series 100-26, 2020).
Read source
→
NIST · 2020
Inadequate data-format interoperability costs the sector $20.9 to $42.9 billion a year, per NIST (Advanced Manufacturing Series 100-26, 2020).
Read source
→
FMA · 2023
Internal scrap and rework rose from 1.0% to 1.4% of sales, per the FMA benchmarking survey via The Fabricator (2023).
Read source
→
In short: over-dimensioning is the habit of dimensioning every edge, radius, and hole instead of only the features that determine whether the part works. A drawing dimensioned to function includes the minimum set of dimensions needed to make and inspect the part, placed from a sensible datum scheme, with tolerances tight only where function demands. That is the difference between a print a machinist can build from without a question and a page they have to decode.
What’s Wrong With Dimensioning Everything?
A drawing which says everything says nothing. The first time an engineer tries an auto-dimensioning tool, the output looks impressive: every edge, radius, and hole dimensioned automatically. The second time, they notice the problem. The tool dimensioned all of it, and the one dimension that actually controls fit is now lost in a wall of numbers. This came up in call after call, unprompted, as the single most common complaint about automated drawings.
An engineer at a consumer-appliance manufacturer, reviewing a trial, said the output’s detailing is on the higher side, more than what is done internally, and asked us to focus on dimensioning the most critical features and not over-tolerancing. A construction-robotics team said there was simply too much data on the page for a shop to work from. A founder who builds CNC software framed it cleanly: a drawing emphasizes what matters, it doesn’t just explode dimensions.
That is the distinction. Exploding dimensions is easy, and any tool can do it. Emphasizing what matters is the actual skill of drafting.
Why Over-Dimensioning Costs Real Money
A cluttered drawing slows the shop, inflates the quote, and lets defects through inspection. It is tempting to think more dimensions are safer. The opposite is true.
It confuses the shop: a machinist reading 1,500 dimensions cannot tell which ones are critical, so the features that determine function get the same weight as a cosmetic edge. It inflates quotes: when everything looks tight and critical, manufacturers price for the worst case, and you pay for precision you never needed. It creates non-measurable dimensions: dimension every edge and some of those callouts cannot be inspected as drawn, so the drawing contradicts itself. It stacks tolerance: chained, redundant dimensions let tolerance accumulate feature to feature until a critical dimension drifts off the part.
The engineer at the appliance manufacturer summed up the stakes: if the drawing is good, everything else follows; if the drawing has loopholes, it will come out in the lifecycle. A non-measurable dimension is a callout an inspector cannot actually measure as drawn, which makes it a defect rather than clutter. As the appliance engineer put it bluntly: it is a crime if you have a dimension on the drawing that’s non-measurable. Dimensioning to function eliminates these by construction: every callout references a datum or feature the shop can physically measure from.
How Hanomi Dimensions to Function
To dimension to function means to include only the dimensions needed to make and inspect the part, place them from datums rather than chaining, and state each one once. Dimension the functional features first, build a reference structure the shop can measure from, apply tight tolerances only where function demands, use a sensible datum scheme of three datums, and make sure every dimension is measurable as drawn.
hanomi, an AI tool that generates production-ready 2D manufacturing drawings from 3D CAD models, dimensions to function rather than exploding every number onto the page. It reads assemblies to tell which features actually locate and mate the part, places dimensions from a sensible datum scheme, applies your tolerance block automatically, and learns your dimensioning conventions from your existing drawings. When a feature is genuinely ambiguous, it flags it for your review instead of guessing, and you approve every drawing before it ships. Want drawings dimensioned to function, to your company’s standard, straight from your 3D model? Generate your first drawing free at hanomi.ai.
Frequently Asked Questions?
Stay in the loop
Subscribe
In case you missed it
Read more
→