This gets REALLY deep, but a lot of this is documented in the help files.
WHAT THE BDT VALUE REALLY MEANS (OR HOW TO FIND A MEANINGFUL VALUE TO PUT INTO THE BDT) THIS IS WHY SOMETIMES IT DOESN’T “APPEAR TO BE WORKING”. IT IS A VALUE USED AS PART OF A MORE COMPLEX FORMULA THAT I’LL EXPLAIN NEXT. NOTE: CATIA DOES NOT SIMPLY ADD OR SUBTRACT THIS VALUE FROM THE LENGTH OF THE FLAT PATTERN. For any angle greater than 90deg and less than 105deg, the deduction is interpolated using a ratio between the values. If our angle is 105, the deduction is -1.27. So in the image above, if our angle is 90deg the deduction is -3. For any angle greater than listed, the last deduction value is used. You can define as many angle ranges and deduction values that you need, as long as they are listed in order from smallest to largest, because this is how CATIA determines the ranges and interpolates the deduction between the explicitly defined angle values (Zero is implied). If you have more than one value defined in the table, according to the open angle the bend deduction will be read in the Deduction column or interpolated between values. If there is only one value defined in the table, that exact value is applied to ALL ANGLES regardless.Īlso note that if you use an angle in your design that isn’t explicitly defined in the BDT, you will get a warning message in CATIA stating the obvious: In this table, the deduction value is applied to all bend angles from 0deg-90deg. The bend deduction value applied is based on where the actual bend angle falls within the user-defined range. Then, in each of the BendTable Excel files you need to define the bend deduction value (a positive value makes the flat pattern “shorter”, a negative value makes the flat pattern “longer”). Each BendTable is to be a separately defined Excel file and you need to point to it from the master Sheetmetal Standards Excel file. If you wish to use Bend Deduction values, you need to define a BendTable column, directly after the DefaultBendRadius column.
The Bend Deduction Tables are a series of Excel files defining allowable values and value ranges for things like Thickness, Default Bend Radius, the types of Stamps allowed, and the BendTable which manages deduction values.
(Click on images to enlarge, and then hit Back in your browser) Note the difference in the length of the flat pattern. Two parts, with the same final 3D part dimensions.
How the Bend Deduction Tables (BDT) work.This blog article will address two items: