Lasercutting

Go directly to the Creating section to set up your drawing if you already know the first steps.

Introduction

The laser cutter is used to cut and/or engrave different materials. Some preparation is needed before processing materials with the laser cutter. The laser cutter uses vector based drawings from programs like AutoCAD and Adobe Illustrator to make the operations.

This manual explains how to make from your design drawings useful working drawings for the laser cutter. Beforehand some choices have to be made before starting with the working drawings. This will be explained in the first part of the manual. The last part of this manual explains how to make the working drawings.

Possible Choices

First define the goal of the model before starting with the working drawings. In general you can show more details in your model if also the design has more details. The level of detail determines the scale of the model and with that the choice of the materials for the model.

Scale

A model can be made in different scales. The choice for a specific scale is mostly determined by the desired level of detail in the model. A model can be a simplified version of the reality, but also an enlarged detail of a building joint. Basically all scales are possible. For example, scale 2:1 (twice as large) or scale 1:10.000 (10.000 times smaller) and variations like scale 1:800.

• Models between scale 1:1000 till 1:500 are mostly (urban) models showing the main forms of the buildings.

Urban model scale 1:1000

Model scale 1:500

• Models between scale 1:200 till 1:100 are generally whole buildings showing façades relatively in a simple fashion. Mainly the skin and the main construction of the building is shown. The interior is mostly left out.

Model scale 1:200

Model scale 1:100

• Models from scale 1:50 and larger can be parts of buildings, details and enlargements of details.

File:Schaal1 50.jpg

Model scale 1:50

File:Schaal1 5.jpg

Model scale 1:5

Materials

Dependent on the choosen scale and level of detail a choice has to be made for the materials to be used in the model. First choose the materials to be cut or engraved by the laser cutter.

The laser cutters at the Faculty of Architecture are able to cut to different thicknesses per material (see table).

paper and cardboard	till 3 mm
MDF	till 6 mm
perspex (acrylic)	till 10 mm
vivak (PETG sheet)	till 2 mm
plywood 1)	till 2 mm

¹⁾ Due to the inconsistent nature of plywood it is possible that the laser cutter will not fully cut through the material.

Processing

The laser cutter can do three operations.

Cutting (vectors)

The laser beam cuts through the material.

Engraving (vectors)

The laser beam carves the material. The beam does not cut through the material.

Rastering

This is the same as engraving. Instead of carving lines, whole surfaces are carved.

Most fibrous materials like wood, paper and paper have brown or black 'burned' cutting edges made by the laser beam. The thinner the material, the less visible the 'burned' edges are. Almost all plastics have not 'burned' edges. In this case the laser beam melts through the material.

Engraving lines in wood, cardboard and paper are mostly black. An engraving line in acrylic (perspex) looks similar to a scratch. Engraving surfaces on wood are mostly black. Engraving surfaces on paper or cardboard become mostly brown.

Generally engraving lines remain black after (aerosol) painting (see picture model scale 1:100). Engraving lines and deep engraving surfaces in perspex can be filled up with oil pastel (see picture below).

Corners

Corners of the model can be put together in different ways. Bear in mind the thickness of the materials and the chosen corner for your model when making your working drawing.

As mentioned before, first find out the thickness of the chosen materials. Then make up the amount of layers of materials on top of each other and finally choose how to put them together in the corners.

The outside layer compared to a inside layer will stick out in a outside corner. This will be opposite for a inside (see picture).

 Hint! Stick one side of the material with double-sided adhesive foil before laser cutting.
       Cutting holes in adhesive foil afterwards is inconvenient.

The first three corners do not need any treatment afterwards. The last corner is made possible by sanding or milling the edges in a (45°) corner. That is because the laser cutter cannot cut within an angle, but only perpendicular to the surface.

Laser cutting with AutoCAD Drawings

We strongly advise to first finish your design before starting with the working drawings. Afterward changes in the design may cause errors in the working drawing like corners not fitting together.

We assume the drawings are made with AutoCAD in classic view. Commands to be used in this manual are described in three ways.

1. Via the menu bar: Draw > Line
2. Via the toolbar:
3. Via the command-line. Possible abbreviated commands are separated with a comma: LINE, L. Always press enter or spacebar after a command or option.

Adjusting Design Drawings

It is a good custom to work with a copy of your design drawing(s). The design drawings will be used as a template for the working drawings.

Relevant design drawings for your working drawings are ground-plans and façades. With difficult building shapes other drawings can be useful to create the working drawings.

Scaling

First scale the drawings to the scale of the model. In the laser cutter one unit equals to one millimetre. Bear in mind which scale factor to use when scaling drawings. For example, when in a design drawing one unit is equal to one centimetre.

Make sure all layers are on, unfrozen and unlocked to prevent layers being not scaled.

First the whole drawing must be made visible before scaling to the scale of the model.

1. First zoom to make the whole drawing visible
   • View > Zoom > Extents
   • 
   • ZOOM, Z then type E to display the drawing extents.
2. In this example the model becomes scale 1:200
   • Modify > Scale
   • 
   • SCALE, SC
     • Select objects: Type all to select all objects and finish the selection by pressing [enter] or [spacebar] again.
     • Specify base point: Click somewhere in the drawing.
     • Specify scale factor or [Copy/Reference]: Type 1/200 or 0.005 for scale 1:200.
3. Zoom to make the whole drawing visible again.

Tracing Drawings

Create new meaningful layers for the laser cutter. Give layers the same name in other working drawings. This numbers down the amount of layers in the final working drawing. We advise you to create extra layers for construction lines and such. You may also group layers for example with the same prefix in the name of the layer.

We have made two sections for each type laser cutter. Two large laser cutters with a working area of (l x w) 800 x 450 mm are available and two small laser cutters with a working area of 600 x 300 mm.

Colour settings for the laser cutter

When the floor-plans and the façades of the design drawings are drawn right, then you should start tracing with the façades without problems. When drawing bear in mind how your corners of the façades will be put together and by how many layers of material the façades will exist.

In the edited working drawing below you can see that the façades on the sides will be put on the sides of this façades. In this case the thickness of the materials (1 mm cardboard and 1 mm perspex) has been into account, which will be put to the sides. The corners of the sides have an offset of 1 mm per layer (cardboard and perspex)

The cleaned up drawings below are the working drawings for the laser cutter

The outline of the building can be drawn with the help of the floor-plans. This will be the basis for the floors and possible flat roofs of the model. The outline is then offset to the inner side on those places where a façade will be. The amount of the offset depends on the total thickness of the façade. There might not be a need for an offset of the outline at open parts of the façade like balconies.

Some rough-and-ready rules concerning distances between lines:

• Make sure the minimal distance between two cutting lines is 0.8 mm. This prevents material between the two lines being burnt or melted away while cutting.
• Make sure the minimal distance between a cutting line and an engraving line is 0.4 mm. An engraving line might not be visible when it is too close to a neighbouring cutting line.
• For a regular line pattern we advise a minimal distance of 0.4 mm. The pattern might look busy if the distance is smaller.

After scaling the line patterns might not meet the rules above. Adapt the lines to the rules above. After all, a model is a simplification of reality and is not an exact miniature of reality.

Draw hatches, patterns etc. as separate lines, circles, arcs etc. and not as a 'block' or a 'hatch'.

Only engraving surfaces are possible as a 'solid hatch'.

1. Check if the right layer (engraving surfaces) is current.
   • Draw > Hatch...
   • 
   • HATCH, H
2. Use the same settings as below.
   
3. Pick a point inside the boundary or the boundary itself.
4. Click OK in the dialog box to confirm.

 Beware! A line in layer engraving lines is not by definition a very thin engraving surface.
         The laser cutter executes these lines sometimes as an engraving line or even as a
         cutting line. Erase those lines if such an execution is not desirable.

After tracing per material everything can be copied to the final working drawings for the laser cutter.

Making Working Drawings

Creating

First check if you have set the following layers right (see figure).

• Turn plotting off for the border layer;
• Select blue and not index color 170;
• Select white and not index color 255;
• Finally select red and not index color 10.

Colour settings for the laser cutters

Material Sizes

Make the border layer current and draw a rectangular border with the same size as the material to be cut.

The maximum working area for the small laser cutter is 600 x 300 mm with a margin of 5 mm on all sides. This is also a common size for materials when ordering.

Another common size when ordering materials for the laser cutter is 765 x 450 mm. These materials can only be used for the large laser cutter. The maximum size of the working drawing for the large laser cutter is 800 x 450 mm with a margin of 5 mm on all sides. Larger materials will not fit in the machine.

Own material can have all sizes and shapes as long as it is not larger than the working area of the laser cutter.

Beware! Materials containing chloride will not be cut in the laser cutter.
        In case of doubt the material will be refused.

Copy everything to the working drawings and arrange everything within the rectangular border. The drawing can be cleaned up after copying and arranging. When drawing and arranging it might happen that some lines will be double (on top of and parallel to each other). At first sight these kind of lines are not easy to discover.

Cleaning up

Depending on your AutoCAD version there are different ways to erase double lines or lines which are too close to each other. AutoCAD installed with Express Tools has a function 'Delete duplicate objects'. Autodesk Map 3D has a function called 'Drawing Cleanup'.

AutoCAD with Express Tools

1. • Express > Modify > Delete dublicate objects
   • OVERKILL
2. Select the objects you want to clean up.
3. After selecting a dialog box like below appears. A higher value for Numeric fuzz means that lines which are near close to each other are also handled as double lines. Value 0.1 means that parallel lines within 0.1 units are considered as double lines.
   
4. Leave other options as they are and click OK to clean up the drawing.

Autodesk Map 3D

1. Open het dialog box of Drawing Cleanup
   • Map > Tools > Drawing Cleanup...
   • 
   • MAPCLEAN
2. A dialog box like below appears. It is possible to clean up the drawing by layer. If you clean up the drawing all at once, Drawing Cleanup might 'decide' to erase a cutting line instead of an engraving line. To avoid this click on the button drawn a circle around and proceed by clicking Next.
   
3. Do the same as in the dialog box below. Mind the order of 'Break Crossing Objects' and 'Delete Duplicates'.
   
4. Click Finish to clean up the drawing.
5. The following messages can appear in the command-line:
   • If double lines are present
     3 object(s) found

Please wait ...
Deleting previous markers...
Cleanup statistics:
Modified object(s)  :0
Deleted object(s)  :1
Created object(s)  :0
   • If double lines are not present
     2 object(s) found

Please wait ...
Deleting previous markers...
0 errors were detected by Drawing Cleanup.

Handing in

This was the last action making the working drawing for the laser cutter. It is time to save the drawing and hand it in with the order form at the CAM-lab. Order forms are available at the CAM-lab.

Laser cutting with Adobe Illustrator files

In general AutoCAD will be sufficient to make different parts for your model with the laser cutter. Creating logos, nameplates and so on are more easily created with Adobe Illustrator.

Creating

After opening Illustrator create a new document via File > New... or CTRL-N.

1. Set your units into millimeters.
2. Fill in 24 in for the width and height for use with the small laser cutter and fill in 32 in for use with the large laser cutter. The numbers will automatically change from inches to millimetres. Do NOT fill in the material sizes!
3. Set the Color Mode to RGB.
4. Finally set the Raster Effects to Screen (72ppi) and finish with OK.

You can only use the upper part of your artboard. To prevent parts of your drawing getting outside the 'printable' area of the laser cutter place a horizontal guide as a reminder.

Placement guides:

• 304,8 mm (12 inch) from above or below for the small laser cutter.
• 457,2 mm (18 inch) from above or 355,6 mm (14 inch) from below for the large laser cutter.

If your material is smaller than the working area of the laser cutter, begin drawing from the upper left corner.