Sheet Metal Setback Calculator
Calculates outside setback from the bend tangent intersection. The calculation answers one defined question; nearby operating losses and constraints remain separate.
Enter the fabrication dimensions
Setback
Setback: conclusions supported by the calculation
This is geometric setback for the included bend angle; drawings using complementary angles must be converted before entry.
Springback, grain direction, tooling condition, thickness tolerance, forming history, and material variation can shift a sheet-metal result. The worked condition ties this guidance to inside bend radius rather than to an unlabeled assumption.
The question answered by setback
If the next geometry changes, continue with sheet metal bend deduction, sheet metal k factor and sheet metal bend allowance.
The question answered by setback: focus on bend angle
The equation uses inside bend radius, material thickness, bend angle to report setback in in. This is geometric setback for the included bend angle; drawings using complementary angles must be converted before entry.
A 90-degree bend with 0.08-inch radius and 0.06-inch sheet has 0.14-inch setback.
Setback: investigating an outlying answer
Estimate the order of magnitude before calculating. Then change one input while holding the others fixed and predict whether setback should rise or fall.
Rearrange SB = (R + T) tan(A/2) to recover one entered value. Agreement with the source record checks the algebra in a different direction.
Setback: focus on bend angle: investigating an outlying answer
Sheet thickness, bend geometry, tooling, material properties, and blank dimensions should describe the same fabrication state. This page preserves inside bend radius and bend angle with the answer for that reason.
A reproducible sheet metal setback record includes the raw measurements and their units. That record makes it possible to separate a data correction from a change in the equation.
Inside bend radius: effect of a revision
Confirm material thickness, temper, grain direction, tooling style, and bend sequence before transferring setback to a flat pattern or press-brake setup.
Preserve the entered inside bend radius and bend angle in the flat-pattern drawing. If either changes, rerun the relationship and identify the revised material, grain direction, tooling, and bend setup rather than editing a rounded result.
Inside Bend Radius, bend angle, and the reported output
Confirm material thickness, temper, grain direction, tooling style, and bend sequence before transferring setback to a flat pattern or press-brake setup.
Preserve the entered inside bend radius and bend angle in the flat-pattern drawing. If either changes, rerun the relationship and identify the revised material, grain direction, tooling, and bend setup rather than editing a rounded result.
Checking the substitution before interpreting setback
Set up the sheet metal setback relation on paper or in the job record before evaluating it. Keep inside bend radius, material thickness, bend angle attached to the same part, machine, material, and observation window.
Cancel or combine the entered units before accepting setback. The surviving dimension should agree with in, and any conversion factor should remain visible in the work.
Setback: practical meaning in context
Store setback with its input values, units, date, product or operation, and the equation version. Do not let extra displayed digits imply measurement accuracy the source data did not have.
Store a guard-digit version of setback for follow-on work and a rounded version for communication. Label them so one is not mistaken for the other.
Interpreting setback in practice
What can cause a surprising setback answer?
First check the unit basis and whether inside bend radius and bend angle belong to the same condition. Then verify any zero divisor, percentage conversion, or empirical constant.
Where should the value for inside bend radius come from?
Use the source identified by the flat-pattern drawing and keep it on the same basis as bend angle. A catalog limit and an observed average should not be mixed without explanation.
Can inside bend radius and bend angle come from different runs?
Only when they describe a combination that can occur together. Preserve the same material, grain direction, tooling, and bend setup throughout the calculation. For this calculation, that check applies directly to setback.
Which entry has the strongest effect on setback?
Inspect the exponents, products, and divisors in SB = (R + T) tan(A/2). Then change inside bend radius by a controlled amount while leaving the other fields fixed.