Laying it out by hand
Every tool on this site does arithmetic a fabricator can also do with a rule, a compass and a calculator. These guides show how: the method behind the tools, step by step, a worked example whose numbers you can check, and the sources it comes from.
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How to lay out an eccentric reducer by hand
Both shop methods for an offset reducer — from the apex, and by triangulation between the ends — step by step, with a worked 300 to 150 example.
The tool: Eccentric (Offset) Reducer Flat Pattern
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How to lay out a square-to-round by hand
Triangulation step by step: the four flat sides, a fan across each corner, true lengths from right triangles — on a worked 600 × 400 to 300 example.
The tool: Square / Rectangle to Round Transition
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How to lay out a cone or frustum by hand
Slant height, the two pattern radii, the sector angle — and one chord across the sector that fixes it exactly, on a worked 600 to 300 example.
The tool: Cone / Frustum Configurator
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How to lay out a pipe saddle template by hand
The branch end of a tee by parallel-line development: stretch-out, twelve ordinates from one formula, a smooth curve — on a 4-inch onto 6-inch example.
The tool: Pipe Cut Template Builder
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How to lay out a lobster-back elbow by hand
Segmented elbow layout: the half-segment rule for the cut angle, throat and heel lengths, template ordinates and cutting from one pipe.
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How to work out the flat length of a bent part
Straight legs plus bend allowance, or outside dimensions minus bend deduction — the same blank two ways, and the bend-angle trap that catches most people.
The tool: Single Bend Flat Pattern Configurator
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How to lay out a bolt circle by hand
Equal hole spacing on a PCD two ways — dividers set to the chord, or coordinates from the centre — with a worked eight-hole flange.
The tool: Flange / Bolt Circle DXF Generator
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How to lay out a rectangular hopper by hand
Four flat trapezoids: each panel’s true height, where its top edge goes, and a diagonal check — centred and offset, on a worked 600 × 500 to 200 × 150 hopper.
The tool: Hopper & Transition Builder
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How much force does a bend take? Press brake tonnage by hand
The force for a 90° air bend from the tensile strength, thickness, die opening and length: a worked 3 mm example, the limit on the tools, and how far two makers’ charts differ.
The tool: Press Brake Tonnage Calculator
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How short can a flange be? Minimum flange length for air bending
Choose the V-die from the thickness and the radius, then allow about 0.7 × V to the outside of the bend — with a table by thickness and a worked U-channel.
The tool: Sheet Metal Profile Builder
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How to find your K-factor from a test bend
Cut a strip, bend it, measure the flanges, then work back through bend deduction and bend allowance to K — with a worked 2 mm strip and the two traps in the name.
The tool: K-Factor Calculator (from a Test Bend)
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How to work out the weight of steel plate by hand
Volume times density, with the density traced to its source — a worked 2400 × 1200 × 6 mm plate, a disc, a tube, and the per-square-foot figure in inches.
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How long a blank does a rolled cylinder need?
The circumference on the mean diameter — from an inside or an outside size, less any seam gap — with a worked 1000 mm shell in 10 mm plate and the mistake that costs 31 mm.
The tool: Rolled Cylinder Blank Calculator
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How to work out a pipe offset by hand
Travel and run from the offset and the fitting angle, the rolling offset, and the cut length after take-outs — checked against an Army manual and a 1920s handbook.
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What a sheet metal gauge number means
A gauge number is not one thickness — how the 1893 law defined it by weight, why steel, galvanized and aluminium gauges differ, and a side-by-side table from the cited sources.
The tool: Sheet Metal Gauge Chart and Converter
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How to lay out a sheet metal box or tray by hand
The blank size each way, the bend lines, corner notches that clear both bends and the folding order — with a worked 300 × 200 × 50 tray in 2 mm.
The tool: Box and Tray Blank Calculator
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How to lay out a sphere or dome in zones by hand
Divide the quarter circle, produce each chord to the axis, lay out every zone as a cone frustum and cut the crown disc — with a worked 1000 mm hemisphere.
The tool: Sphere and Dome in Zones