Cone / Transition Flat-Pattern Generator

Full-scale printable developments — full cone · frustum / transition · lobster-back elbow

Enter diameters and height (or slant), preview the developed sector or gore stack, then download a tiled actual-scale PDF with tape/overlap marks and a reference square on page 1. No seam allowance is included — add yours for lock seam, weld, rivet, or solder.

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How to use: Pick a mode (full cone, frustum/transition, or lobster-back), set units, enter dimensions, and review the preview plus readout. Open Show the math / derivation to see sector radii and included angle. Download the full-scale PDF, print at 100% / Actual Size, measure the reference square, then add seam allowance before you cut. See the guide and seam allowance explainer.

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Catalog gaps: No hand seamer / seamers, rivet gun, or sheet-metal brake products exist in the TestTalkHQ affiliate CSV at publish time — we do not substitute unrelated electrical or welding gear for those roles.

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Three Pattern Modes, One Print Workflow

Full cone develops a right circular cone into a sector. Frustum / transition develops a truncated cone (duct reducer / hopper transition) into an annular sector. Lobster-back elbow stacks mitered gores for a segmented pipe/duct elbow. All three export the same way: multi-page tiled PDF at 1:1 with overlap/tape guides.

Why Seam Allowance Is Left to You

Lock seams, butt welds, riveted laps, and soldered seams need different overlaps. The tool draws the finished developed surface only so you are not stuck with a wrong default. Typical ranges live in Seam Allowance — How Much to Add for Your Joining Method.

Same Family as Tube Notch Templates

If you need wrap-around pipe coping templates instead of cone developments, use the Tube Notch Template Generator — same print-at-100% / reference-square discipline. For brake work after blanking, see the Sheet Metal Bending Guide and Bend Radius Calculator.

Need Square / Rect to Round Instead?

For square, rectangular, or offset-to-round transitions (triangulation development with DXF + full-scale PDF), use the Square-to-Round Transition Flat-Pattern Generator — sibling to this cone / frustum / lobster-back tool. See also the which-to-use comparison.

Related Calculators & Guides

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Print at 100% and verify the reference square. Thin-material development assumption. More tools at WeldKit and TestTalkHQ.com.

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