BUYER RESOURCES / FORMING TOOLS

Channel cut size
& bend allowance

Start with an L, U, C, Z, lipped Z, V, W or N profile. Edit every leg and bend, identify the measurement reference, and estimate the flat blank before forming.

Presets are editable example shapes, not standardized channel sections. Confirm the drawing matches your part. K-factor and inside radius must match your material and actual forming process; validate a sample before production cutting.

Define your profile

Profile presetThickness unitMaterial thickness (in)Inside radius modeDefault inside radius (in)Default K-factorWeight density (lb/in³)Starting orientation (degrees)

In thousandths mode, 89.7 means 0.0897 in; 125 means 0.125 in. Gauge values use our nominal carbon or galvanized steel reference cards, not stainless or aluminum gauges. Inches offers 1/16 through 1/2 in, in 1/16-in steps. Use thousandths for measured thicknesses between those sizes. All other dimensions remain in inches.

0.42 is the Blue Star Metals shop starting K-factor for the default setup. Confirm it for your material, thickness, radius and tooling; use a measured test bend to calibrate when needed. Weight uses a 0.2836 lb/in³ carbon-steel density estimate; enter the appropriate density for your actual material. Enter decimals or fractions such as 1/8 or 1-3/4. The part length runs along the channel; it is separate from the cross-section legs.

Default reference for leg dimensions

Choose a reference beside every leg. Use default follows the selector above; individual overrides stay in place when the default changes. Enter each leg along its own direction between the dimension endpoints shown. These are not overall height/width or diagonal measurements. Virtual sharp means the theoretical corner where extended flat faces intersect. Tangent mode excludes all curved bend portions.

Press brake planning

Tensile strength (ksi)Bottom V-opening (in)Planning allowance (%)Total press rating (US tons)

90° air-bend estimates. For A36 steel, 36 ksi is the minimum yield-strength reference, not the tensile-strength input used here. The 60 ksi tensile value is a starting reference; enter the actual tensile strength for your material. Yield, tensile and shear strength are different. Weight density does not determine tensile strength. V-opening is the width of the bottom die, not ram depth. Blank V uses 8× thickness up to 1/2 in, otherwise 10×.

Part measurements

Part length along channel (in)

Length runs along the channel. The leg dimensions below define its cross-section.

Leg dimensions

Leg letters and ID/OD references match the drawing
Leg	Entered dimension (in)	Reference

Bends in order

Angles are rotation from flat: 0° is unbent; 90° makes a right-angle corner; 135° leaves a 45° opening. Left/right follows the path from leg A. Radius and K overrides are optional; blanks use the defaults above. Hems and compound curves are excluded.

Bend	Rotation °	Direction	Inside R override	K override

Check the cross-section

Cyan = Face ANavy = Face B

Arrows identify each entered leg. Circled numbers identify bends. Confirm all bend directions and dimension endpoints before using the cut size. No tool access or springback simulation is performed.

ESTIMATED DEVELOPED BLANK WIDTH

Bottom die & force estimate

Basis: Wysong air-bending calculator. For machine/tool load limits and die inventory, use the full press brake calculator.

Developed strip

Blue regions are bend allowances. Dashed stations mark their centers from the left edge of the flat blank. These are layout references, not press-brake backgauge or NC instructions.

Ideal developed size only. Cutting trim, kerf, notches, hems, weld gaps, end allowances, machine access and forming sequence are not included.

Check each straight portion

Leg	Entered	Reference	Setbacks removed	Straight (in)

Bend allowances and flat stations

Bend	Rotation	Inside face	R (in)	K	BA (in)	Local OD deduction (in)	Flat center (in)

Local outside bend deduction is 2 × outside setback − bend allowance. Mixed ID/OD entries are converted separately to straight lengths. Do not subtract every OD deduction from Face A/B dimensions across reverse bends; the calculator converts each face to tangent lengths first.

Calibrate K-factor from a measured single test bend

Use one test bend made with the same stock and tooling. Enter the original flat width, actual inside radius and bend rotation, and both outside leg dimensions measured to their virtual sharp. These measurements do not describe a multi-bend channel.

Calculation basis

For each bend, BA = bend rotation in radians × (inside radius + K × thickness). Inside setback = R × tan(rotation ÷ 2); outside setback = (R + thickness) × tan(rotation ÷ 2). Developed width = all straight tangent lengths + all bend allowances. Estimated part weight = developed width × part length × thickness × entered density; this is the gross rectangular blank weight before material removal.

Each selected material face uses the local inside or outside setback according to bend direction. The material drawing uses mid-thickness geometry, not a neutral-axis location. Bent sheet is modeled as constant-thickness planar cross-sections; the overlap check is a sampled geometric check, not a CAD manufacturability analysis.

References: SOLIDWORKS bend allowance and virtual-sharp definitions, Autodesk K-factor calibration guidance.

Weight reference: JADCO steel weight calculator uses the same approximate steel density of 0.2836 lb/in³.

From a flat blank to a formed part

Review press brake forming capabilities and send your drawing for job-specific confirmation. Calculator output is a planning estimate.

Press brake forming capabilities ↗ · Discuss your order ↗

Channel cut size& bend allowance