What DSTV / NC1 is doing in your inbox
DSTV (NC) files are a long-standing exchange format for steel profile parts — beams, columns,
plates in some workflows — carrying enough geometry for saws, drills, and coping machines to
manufacture without re-modeling. Tekla and other detailing packages export .nc1 /
.nc files that list profile type, length, hole patterns, notches, cuts, and marks.
When something is wrong in the NC1, the machine will happily cut the wrong thing at production speed. A five-minute visual check before nesting beats a scrapped W21 and a schedule delay.
Why a 3D viewer helps
Raw NC1 is text. Experienced detailers can read blocks, but hole gauges, slot orientation, and notch direction are easy to mis-scan. A client-side 3D viewer parses the file locally and shows the solid with holes and cuts in place. You are not uploading proprietary shop files to a random server — the browser does the work on your machine.
Use the viewer as a pre-flight, not as the system of record. The model and the approved drawing still win disputes. The viewer wins “did this export look insane before we burned it?”
What to check on every file
- Profile and length — Does the shape designation match the drawing? Is overall length the finish length you expect (watch for saw kerf conventions)?
- Part mark — Assembly marks and piecemarks should match the nest list.
- Holes — Quantity, diameter, gauge lines, edge distances. Look for mirrored patterns on the wrong flange.
- Slots and overlays — Orientation and whether slots are intended as short slots or long adjustment slots.
- Notches and copes — Depth and which end. A cope on the wrong end is a classic export or mapping bug.
- Saw cuts / miters — Angle and direction for beveled ends.
Client-side vs “upload our files” portals
Fabricators are rightly paranoid about sending NC1 libraries to third-party clouds. A local viewer keeps IP on the workstation. That does not remove your obligation to follow IT policy; it does remove an unnecessary upload step for a quick geometry sanity check.
Where NC1 checks fit in the production pipeline
- After export, before nest — Detailer or checker spots inverted holes.
- At production control — Verify the file attached to the work order matches the revision on the drawing stamp.
- After a software or mapping change — Re-check a sample of each profile family when post-processors change.
Limits
A viewer will not validate mill certs, grade substitutions, or whether the connection designer meant 13/16″ holes for 3/4″ bolts. It will not replace clash detection in the BIM model. It will show you if the export looks like the part you think you are about to cut.
Make pre-flight viewing a habit on unfamiliar profiles, first-article parts, and any file that came back from a revision storm. Steel is expensive. Seconds of looking are not.