Allowances and seam lines in VLOTHO CAD patterns
How to distinguish the cut edge, baseline, and stitching line, check the seam allowance and seam offset in patterns for bags, cardholders, and other models.
Before changing the allowance, determine which line the model dimensions are based on. In VLOTHO CAD, this is indicated next to the parameters and on the design page. The rules differ between models.
Cut edge, baseline, and stitching line
| Designation | Meaning | What to check |
|---|---|---|
| CUT — cut edge | The outer contour of the piece and the specified cutouts. | The blank is made from it. |
| BASE — baseline | The model’s reference geometry. | It does not always coincide with the stitching line or cut edge. |
| STITCH — stitching | Seam lines specified by the design. | Fit with the assembly and open edges. |
| HOLES — holes | Hole markings in manual-stitch mode. | Pitch, diameter, and alignment of the pieces. |
Bag: dimensions along the baseline
In a flap bag the parameters describe the basic construction, while the allowance affects the cut-edge contour. Therefore, the width from the table cannot be compared with the outer width of the paper blank without checking. After changing the allowance, export the patterns again and check the joins.
Cardholder: cut-edge dimension and seam offset
For a cardholder dimensions are specified along the cut edge, while the seam is offset inward. An additional allowance along all edges is not automatically required. Check the internal space for the card, the number of layers, and access to the pockets. The top edges of the pockets are left open.
Other small products may also use a seam offset from the cut edge. Follow the label for the specific model. The binding strips for a bag with a short handle are already specified along the cut edge: a second allowance will change their width.
Hand and machine stitching
Manual stitching mode adds holes where provided for by the model. Changing the stitch spacing affects the markings. Compare mating pieces after all changes. The presence of a line or hole in the file does not by itself determine the machine settings and tooling.
How to choose the seam allowance
There is no single value for every type of leather and process. Consider the joint, edge finishing, material stack thickness, and equipment. Start with the specified parameters, check the paper assembly, then make a test joint using the selected material. The designer does not calculate all technological allowances for folding and skiving.