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# Why the scheduled cut length differs from the sum total of the input parameters.

PROKON’s detailing programs are based on the guidelines, set out within the various detailing codes. All calculations and assumptions made, are therefore, code dependent. This article is based on the South African detailing code, SANS282-2004, and will include an example of a shape code 55.

In majority of cases, the value of the last input parameter of your shape code, will form part of the redundant dimension within your bending schedule. The scheduled cut length will differ from the sum of the input parameters, for various shape codes, as the cut length is calculated from a specific equation, discussed throughout this article.

A shape code’s main dimensions are defined as orthogonal – meaning, the dimensions are given as horizontal, or vertical, as seen below:

However, when starting to bend a straight bar, the bend radii will come into play and affect the calculation of the cut lengths. The calculation of a shape code 55’s cut length is set out within Table 1 of the code (SANS282-2004, Section 4), as seen below:

As seen within Figure 2 above, the equation used to calculate a shape code 55’s cut length is as follow:

If you draw this shape code 55 out, with specific dimensions, your total perimeter length (from A-E), will be 1450mm.

The loss in length between the calculated perimeter and the scheduled cut length, is due to the bend radii, and diameters of the bars, as described within the equation seen within Figure 3 above. If a straight bar is bent to a certain specification, the calculation set out within the detailing code is used to calculate the required cutting length.

If you calculate the cutting length manually and use the guidelines within Figure 3 from the detailing code (SANS282-2004, Section4), for the correct values of radii and diameters, you can calculate your shape code’s cutting length, as seen below:

The manual calculation of the cutting length can be compared to the calculated and generated cutting length within the bending schedule of Padds, as well as Probar 2D.