Practical tools for measured work
Pipe & Tube Notch Template Generator
Generate a full-size fishmouth or saddle template for the theoretical intersection between two tubes.
Calculate the layout, check the diagram, then print the result for the shop or jobsite.
the tube being sat against
the tube being notched/cut
90° = perpendicular T-joint
How it works
The branch tube's surface is parameterized by rotation angle around its own circumference. For each angle, the tool solves for the exact point where that surface meets the main tube's cylindrical surface (assuming the two tube axes intersect), producing the classic fishmouth/saddle cut curve. Print the template at 100% scale, cut it out, and wrap it around the branch tube - the printed circumference exactly matches the tube's outside circumference.
Worked example: a 90-degree branch produces a symmetric saddle. Reducing the intersection angle lengthens the profile around the branch circumference, so mark the template seam and tube orientation before cutting.
Limitations
This assumes the two tube centerlines intersect (no offset/miss-distance) and that both tubes are simple round cylinders. Wall thickness, weld gap and coping for square/rectangular tube are not accounted for.
FAQ
Which diameter should be "main" vs "branch"?
What if the template is wider than one page?
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