- Background (muslin)
- Light (faded chambray)
- Dark (indigo)
Block No. 45 · pinwheel
Double Pinwheel Quilt Block
Also known as Old Windmill (three-triangle version), Whirlwind, Modern Envelope, Twin Sisters, Water Wheel
Part of: Pinwheel Quilt BlocksHalf Square Triangle Quilt BlocksQuilt Blocks For Beginners
Double Pinwheel places two sets of turning blades in the same block. The three-triangle quadrants also appear in mirrored form under Whirlwind and in older Windmill naming traditions.
Version note: Whirlwind is included as the mirrored three-triangle variant, not a separate near-duplicate page.
- Level
- Confident Beginner
- Grid
- 4 × 4
- Pieces
- 12
Chart
Cutting for a 12" block
4 × 4 grid. All cuts fall on 1/8" ruler marks. Unfinished block: 12 1/2".
| Fabric | Shape | Cut | Size | Then | Pieces used |
|---|---|---|---|---|---|
| Background | Quarter-square triangle | 1 | 7 1/4" square | Cut twice diagonally (4 triangles each) | 4 |
| Light | Quarter-square triangle | 1 | 7 1/4" square | Cut twice diagonally (4 triangles each) | 4 |
| Dark | Half-square triangle | 2 | 6 7/8" square | Cut once diagonally (2 triangles each) | 4 |
Method
Piecing steps
Step 1: Subcut the large HST parents once diagonally and the QST parents twice diagonally.
Step 2: Sew one background QST to one light QST along a short edge. Join the resulting pieced triangle to a dark HST along the long diagonal.
Step 3: Make four quadrants and trim each to 6 1/2". Rotate each one a quarter turn from its neighbor.
Step 4: Join the top and bottom pairs of quadrants, then match the center points and sew the final seam.
Step 5: Join the sections with a 1/4-inch seam allowance, matching the marked intersections. Press and check the unfinished block measures 12 1/2" square.