Define and match seams

What you are trying to accomplish

Name the exact outline spans that sew together, tell PatternForge how they are related, and review whether their recorded lengths and notch positions agree with that intent.

This is an Advanced checking workflow. It documents relationships between already-created pieces; it does not draft, reshape, or sew the seams for you.

Why it matters

Related pieces are easy to confuse when a project contains several similar edges. A named edge such as “Front side seam” is more useful than an anonymous curve.

Seams that sew together often need compatible seamline lengths, but not every pair should be identical. Sleeve-cap ease, gathers, pleats, or stretch may create a deliberate difference. PatternForge needs that intent recorded so it does not treat purposeful ease as an error—or an accidental mismatch as acceptable.

The check compares digital edge relationships. It is not a full seam-walking or truing operation and cannot judge construction order, turn of cloth, folded darts, or fabric behavior.

Step by step

1. Confirm both piece outlines are closed, clean, and set to the correct line meaning. Compare sewing lines when the sewing relationship matters, not arbitrary outer cut edges.
2. Open Advanced → Seams & matching.
3. Choose Mark an edge.
4. Click one anchor at the start of the seam, then a second anchor on the same outline at the end. For a closed outline, PatternForge chooses one of the two possible routes between those points.
5. Select the new edge in the list. Give it a specific name and, when helpful, a role such as side seam, shoulder, armhole, neckline, waist, hem, sleeve cap, or fold.
6. If PatternForge highlighted the long way around a closed piece, choose Flip span (use other arc).
7. Repeat for the edge on the related piece.
8. Choose Match two edges, then click the two named edges.
9. Select the new relationship and name it clearly.
10. Choose the relationship type:
    • match length when the seamlines should agree within the allowed tolerance.
    • ease when one edge is intentionally longer by a known amount.
11. Set the intended ease and tolerance from your approved patternmaking or production standard. Do not invent a convenient value just to turn the status green.
12. Review the A and B lengths, status message, and any notch-correlation warning.
13. Open Pattern Check and repair every unintended mismatch before print or sale.

What success looks like

• Each relationship uses clearly named, correct spans rather than whole-piece guesses.
• The chosen span follows the intended seam on both closed outlines.
• Match-length and ease relationships reflect construction intent.
• Any tolerance is deliberate and documented.
• Corresponding notches occur in a compatible order and location.
• Pattern Check has no unexplained seam warning.
• A separate truing or sample process confirms the relationship is actually sewable.

Common problems and recovery

The marked edge goes the long way around the piece

Select it and choose Flip span (use other arc). Recheck its displayed length and highlighted route.

You cannot mark an edge

Make sure you click two existing anchors on the same path. Use Adjust Shape to add meaningful boundary points if the seam endpoints are not represented yet.

The relationship says the edges do not match

First ask whether the difference is intentional. If not, inspect the source line, calibration, dart or pleat handling, and traced geometry. Fix the cause rather than increasing tolerance until the warning disappears.

An eased seam is reported as a mismatch

Change the relationship to ease and enter the approved intended difference. Confirm which edge is meant to be longer in your construction notes; the numeric relationship alone does not teach the sewing method.

The edges match overall but notch warnings remain

Compare each section between corresponding notches from a shared start point. Move an incorrect notch or repair the edge definition. Overall length agreement cannot replace sectional balance.

A relationship becomes broken

One of its named edges was deleted or changed beyond recognition. Delete the broken relationship or recreate and relink the intended edges.

Cut edges match but the garment seam does not

Recreate the check on the sewing-line relationship. Different allowance treatments, corners, or extensions can make raw cut edges unsuitable for comparison.

PatternForge says “All good,” but the seam still may not sew correctly

The app checked the recorded digital rules only. Close darts and pleats as sewn, true intersections, consider ease and fabric, and sew an appropriate test sample for a new or altered pattern.

Quick safety check

For every relationship, read this sentence aloud:

“The [named edge] on [piece A] sews to the [named edge] on [piece B], with [no intended difference / this approved ease].”

Then confirm the highlight, lengths, notch order, and construction notes all agree with that sentence.

Related tools and next step

Add and verify notches and balance marks, review seam allowance, and use Shape check for the underlying geometry. PatternForge relationship checks support—but do not replace—manual truing, seam walking, and a sewn sample.