A drawing can look right at the wrong size
Zoom-to-fit makes a 10-inch rectangle look much like a 10-millimeter rectangle. The INSUNITS header helps identify the intended unit, but it can be absent or incorrect. Compare a known dimension in the receiving program before preparing any cut.
This tool preserves coordinates
The cleaned export does not rescale or rewrite the unit header. Its dimensions and total supported-curve length remain in drawing coordinates. A nonzero Z or elevation warning means the two-dimensional preview does not describe the whole file.
Check the final receiver
Import the downloaded file into the actual CAD or CAM application and measure a known edge. Confirm the material size and setup independently. Unit-aware arithmetic cannot infer the physical size the designer intended from an unlabeled file.
Use the built-in drawing as a reference
Try the example: a closed 100 × 60 rectangle and a circle of radius 12 share the CUT layer. Its INSUNITS value declares millimeters. The circle diameter should therefore measure 24 mm in the receiving application. These simple known dimensions make an import-scale error easier to detect than the silhouette of an unfamiliar drawing.
Upload an ASCII DXF or paste its complete text, including the closing EOF record. If both are supplied, the uploaded file is used. Run the inspection and read the reported unit declaration, geometry bounds and unsupported-entity findings together. An unknown unit is a request for verification, not permission to assume millimeters.
Keep tolerance in the same coordinate system
An endpoint tolerance of 0.01 represents 0.01 drawing units. That is 0.01 mm in a millimeter drawing but 0.254 mm in an inch drawing. The tolerance helps group endpoints for the diagnostic; it does not rescale the file, move vertices or close gaps. Choose it after confirming units, and save the report with the cleaned drawing so the next person understands the scale of the check.