A designer builds a polygonal 3D model, taking into account the basic requirements of anatomy and composition, as well as the feasibility of assembly from sheet metal. When creating such models, it is important that the polygons are planar: all vertices of a single polygon must lie in one plane. It is also important to minimize the number of internal angles sharper than 90°. The finished model is then passed to a process engineer. The engineer defines the parts, taking into account sheet thickness and bend allowances. He then combines the polygons into parts in a way that reduces the number of internal and flat weld seams, also taking into account the bending limits of a CNC press brake, convenient part fit-up, and subsequent weld grinding. He then produces a set of files for cutting, bending, and assembly.
Differences between drawings for metal and paper models
- Polygon shapes. We prepare drawings for metal and paper in different software. For metal, we design based on the required sheet thickness — most often 1.5 mm. Paper is less than 1 mm thick and, unlike metal, can twist slightly. Therefore, for metal models we straighten the polygons so that 4–6 vertices of a single polygon lie in one plane. Faces with small bend angles are removed by merging adjacent polygons.
- Shape of parts. For metal, we combine several adjacent polygons into small parts and try to form linear sequences so that no more than three bends meet at one point, taking into account the convenience of working on a press brake. With paper, the opposite applies: the fewer glue joints, the better. Parts are therefore larger, consist of many polygons, and fold into box-like shapes. They also include glue tabs (shown in gray fill).
- Assembly method. Internal seams are difficult to grind, so most welds are placed on the outside of the joint. In paper models, by contrast, glue joints are more convenient on internal folds rather than on outer (convex) edges.
- Metal behavior during bending. We account for sheet thickness, material stretching at bend lines, and the resulting offsets and deformations.
- Bend angles. Drawings for paper models do not include bend angles, as this information is not required for assembly.
- Sheet size. For metal, parts are nested on the most common sheet size: 1250 × 2500 mm. The standard paper size is 210 × 297 mm (A4).
The set of drawings includes:
- DXF files for cut and engraving;
- PDF file showing the bend angles;
- PDF file showing the placement of parts on the model.
DXF files for cutting
The drawing is placed on the outer (front) side of the model — this allows the sculpture to be fabricated from different types of sheet metal. If polished (mirror-finish) stainless steel is used for assembling the sculpture, the sheet must be placed on the needle table during laser cutting with the polished side facing up, and the engraving must be on that side.
We provide several DXF file options to choose from:
- DXF files labeled “…-Nesting-…” contain cutting lines only (no engraving). The part contours include stress-relief cuts at bend corners and bend-line notches indicating bend lines without the need for engraving. Part numbers can be marked with a marker after cutting.
- DXF files labeled “…-NestingLabel-…” contain the same cutting lines, including stress-relief cuts and bend-line notches, as well as engraving elements such as bend lines and part numbers. Bend lines in the DOWN direction are marked in red; bend lines in the UP direction are marked in yellow. Engraving DOWN bend lines may cause the metal to begin tearing along the bend line. Engraving UP bend lines, by contrast, may make bending easier.
- DXF files labeled “…-BendingTabs-…”. In this file, some parts include temporary clamping tabs. Small protrusions are built into the cutting contour of the parts. They are located where a bend line converges with the edge at an angle to prevent the metal from being pulled out of shape in areas with a narrow clamping zone. These tabs must be cut off with an angle grinder before assembly.
Note: These files are not prepared for all models. We can provide them on request — please contact us if needed. - “DXF-Separate”. A folder with files where parts are not nested on a sheet; each part is saved as a separate DXF file.
We recommend cutting the parts on a CNC laser cutting machine. The drawings are also suitable for plasma cutting. Parts can also be cut manually using an angle grinder. To do this, print the DXF nesting layout on thin roll paper at a print shop. The density of this paper is close to standard office paper. Roll paper may be of different widths. Most of our drawings are arranged on sheets measuring 1250 × 2500 mm. Accordingly, the roll width for printing such a drawing should be 1250 mm. The printed cutting layout serves as a stencil for cutting the metal parts. The printed parts must be cut out along the contour, glued onto the metal sheet, and then cut out using an angle grinder.
PDF file showing the bend angles
This file shows bend directions and bend angles in degrees. In our drawings, the bend angle is measured from the table surface to the plane of the part, not between polygons.
- UP — bend upward
- DOWN — bend downward
Parts can be bent using a press brake (manual or CNC) or by hand using an angle gauge, a vise, and clamps. To make manual bending easier, the UP bend lines can be lightly scored with an angle grinder. Notching the DOWN bend lines may cause the metal to begin tearing along the bend line.
PDF file showing the placement of parts on the model
This document is not a step-by-step assembly manual. It shows the overall placement of parts on the model with consideration of their visible sides. The assembly sequence can be chosen at your discretion, depending on the size of the model and access to weld seams. Large sculptures are usually easier to assemble from the main volumes toward smaller details. Smaller models can be started from central or smaller elements, gradually building up the form.
Sculpture fabrication steps
- Follow safety regulations and use personal protective equipment.
- Cut the parts from the sheet metal and mark the bend lines and part numbers.
- Bend the parts.
- Tack the model together. Check the fit and alignment of all parts.
- For easier grinding in hard-to-reach areas, the model can be divided into parts. After tacking the entire model together, determine which seams will be convenient to separate along and do not weld them. Weld only the main seams. Cut the tacks, divide the model into parts, weld and grind the hard-to-reach seams. After that, reassemble the model completely.
- Final finishing is up to your preference and artistic intent. Some makers prefer rough welds and a corroded surface, while others choose a perfectly polished finish. Photos on our social media can help you decide — we publish works by different makers so you can see their approaches to finishing. Please use the hashtag #pp_metal when posting your work.