Mark a piece to cut on the fold

What you are trying to accomplish

Tell PatternForge that a traced half piece must be placed on folded fabric so cutting creates one complete, symmetrical piece without a seam along that edge.

PatternForge also has a Fold Line tool. It places an internal fold or crease marking inside a piece. It does not, by itself, turn a whole or half outline into a true cut-on-fold piece. Use the structured 1 on the fold workflow for cutting behavior.

Why it matters

A cut-on-fold instruction changes the shape that comes off the cutting table. If a half piece is treated as a whole piece, the result is too small. If a full piece is placed on a fold, the result is double the intended width.

A real PatternForge cut-on-fold piece stores a symmetrical half, displays its mirrored result, prints Cut 1 on fold, and leaves the fold edge without seam allowance. Typed words alone cannot provide those safeguards.

Step by step

1. Confirm the source piece is truly intended for the fold. Look for a fold arrow, center-front or center-back fold instruction, or reliable drafting information.
2. Confirm what you traced. The common paper pattern is a half piece ending at the fold edge. Do not assume this just because the shape looks symmetrical.
3. Select the piece and open Get it ready.
4. Under How many to cut?, choose 1 on the fold.
5. Answer the half-or-whole question:
   • Choose The half when the traced outline represents one side of the final piece. PatternForge adds a fold axis and mirrored preview.
   • Choose The whole piece when the outline is already complete. PatternForge uses plain Cut 1 because placing that whole shape on a fold would cut it double size.
6. Inspect the fold axis that PatternForge chose. If it selected the wrong straight edge, use the Fold controls and Snap to edge, or adjust the axis before continuing.
7. In the Shape panel, keep the symmetry mode on Cut on fold. Mirrored is a different advanced mode with a movable reflection axis and does not mean the edge must be placed on folded fabric.
8. Confirm the note says the fold edge gets no seam allowance.
9. Use Break apart only if you intentionally want to turn the derived full shape into ordinary editable geometry. This removes the live half-to-mirror relationship.
10. Preview the exported piece and read its cut instruction. It should clearly state Cut 1 on fold and show an unambiguous fold edge.

If you only need to draw a fold or crease line inside a piece, choose Fold Line, place its two endpoints, and edit its angle as needed. Treat that as a marking, not cut-on-fold behavior. Use Construction Line for a separate stitch or placement line.

What success looks like

• You know whether the original outline represents a half or a whole piece.
• A half piece has real Cut on fold symmetry and a fold axis on the intended edge.
• The mirrored preview meets the stored half cleanly without a gap or overlap.
• No seam allowance is added along the fold edge.
• The export says Cut 1 on fold and prints a usable fold indication.
• A whole piece remains Cut 1 rather than being falsely marked for the fold.

Common problems and recovery

PatternForge chose the wrong edge

Use Snap to edge after selecting the intended straight edge, or adjust the fold axis. Inspect the full mirrored preview before accepting it.

The mirrored half has a gap or overlap

Return to Cut on fold mode and snap the axis to the stored half’s actual fold edge. Use Shape check to inspect fold and symmetry concerns.

You chose “The whole piece” by mistake

Undo and repeat 1 on the fold, choosing The half. Verify the fold axis and exported instruction afterward.

You chose “The half” for a complete full piece

Undo or remove symmetry. Mark the complete piece Cut 1 unless the real construction says otherwise.

You added a Fold Line marking but Pattern Check still asks for grain or fold readiness

An ordinary fold-line marking does not create cut-on-fold symmetry. Use 1 on the fold or Make symmetrical, then verify the resulting axis.

Seam allowance appears on the fold

Confirm the piece is in Cut on fold symmetry rather than merely carrying a fold-line drawing. Remove and reapply seam allowance after repairing the fold setup if necessary.

The source has an asymmetric design

Do not force symmetry. Trace the full piece and label left/right or face-up orientation as the construction requires.

Quick safety check

Imagine placing the exported paper on folded fabric:

• Is the paper piece a half rather than an already complete whole?
• Is the correct straight edge touching the fold?
• Will cutting and unfolding produce exactly one intended full shape?
• Is the fold edge free of seam allowance?
• Does the printed instruction agree with the geometry?

Related tools and next step

Review the piece’s grainline, seam allowance, and name and cut label. Use Shape check before Pattern Check whenever the mirrored preview looks uncertain.