Bend mathematics in Excel, checked against bend_calc.py
Bend allowance, bend deduction, setbacks, multi-bend flat length and K-factor calibration as one Excel workbook with live formulas, checked value by value against the tested bend_calc.py.
The free sheet metal calculators run in your browser. This is the same mathematics as one Excel workbook for the press and the planning desk: no internet, no Python, and every cell is a formula you can read.
What is inside
| Sheet | What it does |
|---|---|
| README | Angle convention, every formula, what is and is not claimed |
| Bend | One bend: bend allowance, outside and inside setback, bend deduction, Y-factor, and flat length by three methods that must agree |
| Multi-bend | Up to 8 bends. Flat length from outside legs (bends that all turn the same way) and from tangent flats (any bends, including Z-bends and joggles) |
| K from coupon | Back-calculate the K-factor from one bent test piece, and see how far a caliper error moves it |
| BD table | Bend deduction grid by sheet thickness and inside radius for the angle and K you type |
| BA table | The same grid for bend allowance |
The mathematics
is the bend angle: how far the flange is turned from flat, so a right-angle corner is . These are the formulas of the free, tested bend_calc.py; the workbook gives the same results.
How it was checked
The workbook was recalculated and 196 results were compared with bend_calc.py (single bend, a two-bend U-channel, the K-from-coupon sheet and every cell of both grids). All agree to better than mm. Bad inputs (an angle of 180°, a K above 0.5) show a message and #N/A instead of a number.
What it does not do
- It does not ship K-factors. Published tables disagree, and K depends on your material, tooling and press. K is an input on every sheet; the coupon sheet measures it on your own parts.
- It is not validated against your machine or your CAD flat pattern. It is arithmetic. Bend a test piece and measure before you cut production blanks.
- No SolidWorks bend table (.btl) is included. This download is the Excel workbook only.
- It was verified in LibreOffice Calc. It uses only standard formulas and data validation (no macros), so Excel should open it, but it has not been tested in Microsoft Excel.
Licence
Single: one engineer. Team: up to 5 seats in one organisation. Do not redistribute the file. See the licence schedules and the engineering disclaimer (D-ENG).
Buy
Use Buy Now above. Checkout opens on this page, and your download is on your order page as soon as the payment clears.
- Type
- Template
- Format
- Excel workbook
- Download size
- 15 KB .xlsx
- Price
- $7.99
- License
- Single (1 engineer) / Team (5 seats)
What the template includes
Single bend
BA, OSSB, ISSB, BD, Y-factor and flat length by three methods that must agree, with an input check.
Multi-bend flat length
Up to 8 bends: flat length from outside legs (same-direction bends) and from tangent flats (any bends).
K from a test piece
Back-calculate K from one bent coupon and see how much a caliper error moves it.
BD and BA grids
Bend deduction and bend allowance by thickness and radius for the angle and K you choose.
Get the template
About 15 KB .xlsx. Requires Excel or LibreOffice Calc. Plain formulas and data validation, no macros. Recalculated and verified in LibreOffice Calc; not tested in Microsoft Excel..
Sheet-Metal-Shop-Floor-Workbook.xlsx
Questions, answered
Does it include K-factor values?
No. K is an input. Published K tables disagree, so the workbook gives you the coupon sheet to measure K on your own press and tooling.
Is a SolidWorks bend table (.btl) included?
No. This download is the Excel workbook only.
Is it validated for my machine?
It is arithmetic. It has not been validated against your press brake or CAD flat pattern. Bend a test piece first.
Share this engineering resource
Recommend this template to colleagues.