Laser Cutting

From RISDpedia

The laser cutter is a machine that takes vector based information (your design drawn in autocad or illustrator) and uses a laser set at a specific speed and strength to cut or score a sheet material. There are many limitations and variables in this process, and you must know these before you design what you are making, prepare a file to be cut and choose a material. Trial and error are often helpful, as is consulting with people who have experience using the machine (ie. monitors). The laser cutting machine in the BEB has its own limitations as well, due to the bed size, the input programs it uses and materials that can be cut (for safety reasons). Cutting materials produces a significant amount of off gassing and some materials are banned due to their toxicity. The BEB laser cutter is a small machine of limited strength; it cannot cut metal and the max thickness it can generally cut is 1/8".

Time is a hugely important factor in choosing what and how to design an object that will be laser cut. Thick material will take much more time to cut. Certain materials take longer to cut due to the combination of power and speed a material can withstand. For example, wood may be cut slowly because it burns easily; acrylic may be cut slowly as well, so that it does not melt, especially if the cuts are close together. Intricate designs will take much longer to cut. Many sheets of material will take more time to set up and change between cuts. When planning to make something using laser cut material keep in mind that it may take many hours to cut, and that there are time restrictions on an individual's use of the machine in the BEB. Although laser cutting is a relatively quick, precise and helpful tool, it requires significant planning of your design based on the time it takes to cut the given material and design. Cutting one simple sheet of chipboard may take 15 minutes whereas constructing an architectural site model made of layers may take many many hours, and therefore days.

Contents 1 The following materials may be cut by the BEB laser cutter: 2 The following materials may not be cut by the BEB laser cutter: 3 The following are what you must know when preparing a file to be cut in the BEB: 4 Examples of work that uses laser cutting:

[edit] The following materials may be cut by the BEB laser cutter:

Plexiglass / Acrylic (up to 1/8” thick); Chipboard; Basswood; Foam core (although it will warp and melt); Paper; Plywood (up to 1/8” thick); MDF; Cardboard; Museum board; Butta board; Fiber board; Aircraft plywood; Baltic Birch Plywood (from Metcalf)

[edit] The following materials may not be cut by the BEB laser cutter:

PETG plastic; Vinyl; Lexan; PVC; Foam; Metal (cannot be cut at the BEB, but can be cut)

[edit] The following are what you must know when preparing a file to be cut in the BEB:

1. The BEB laser cutter has a 24" by 36" bed, and this is the maximum size sheet that can be cut. If your material is larger, it will need to be cut down.

2. Although the maximum size is 24 by 36, you must account for at least a 1/2 inch space for leeway; one inch to be safe. So your design may not be bigger than 23" by 35". This is due to the imprecise way in which the machine and the computer program that gives the input negotiate the starting point (0,0) of the cut about to be executed. This imprecise way gives the machine operator more control over where the bottom left corner of the design really is. Imagine that your drawing to be cut is read by the machine as lines on a grid, with x and y coordinates, where (0,0) is the bottom left hand corner. The machine will always respect where these lines are in relation to other lines that you have drawn, but automatically shifts the whole thing as close to (0,0) as possible, presumably to avoid wasting material.

3. You can control where (0,0) is, and where your drawing is on the sheet material by making a small L shaped marker in the bottom left hand corner. This established where the beginning x and y coordinates are and will become part of what will be cut and the space between this marker and your drawing will always be maintained. If you do not want this to be part of your end result, you may draw a box, smaller than 23 by 35 that will act in the same way, but simply cut out a new smaller dimension of material on which your drawing will laser cut.

4. Your drawing must be to scale. In AutoCAD, a 5" line that you draw will be cut out as a 5" line. If you want to make a scaled model, for example at 1":1', you must scale down your drawing in AutoCAD, so that your 15' object in the drawing, scaled down to 15" in AutoCAD will be cut at 15". Use the SCALE command to do this. In Illustrator, draw an object to scale on the page to be printed out. Make this page 24" by 36".

5. To assist yourself in setting up a sheet to be cut, and to assist the monitor, draw a 24" by 36" box to scale in AutoCAD. Orient the box in the "portrait" orientation: 36" rise in the y-axis and 24" in the x-axis. The bottom left hand corner must be at (0,0) in AutoCAD. This box will not be cut in your material, but the monitor needs it to set up the file. Place your L shaped marker at the bottom left hand corner inside this box.

Advanced: use the RECTANGLE command to draw your box in AutoCAD. Start at 0,0 and type REC. Hit Enter, and then type "@24,36" and hit enter again. This will draw a box 24 by 36 inch in size.

6. For each sheet you want to cut, draw a new 24" by 36" box. 7. If you want these sheets to be layered in a way that uses the outside edge of the material in its design, make sure that the L shaped markers are in the exact place in every drawing inside a 24" by 36" box.

8. If you want two types of cuts to be made on the same sheet of material, i.e. a cut and a score, you must prepare these as two separate drawings in separate 24" by 36" boxes. They MUST have the same L shaped marker in the same place. These will be sent to the machine at two different times due to the two different settings (power and speed) required to cut or score. (Use layers in autocad to facilitate this).

9. Make sure there are no overlapping lines, by which I mean lines drawn twice that you cannot detect by eye. The laser will cut these twice and this will result in a darker, thinker line, inconsistent with the others. Use the command DELDUP to identify and delete these, or simply do it by deleting by trial and error.

10. Consider if you want the machine to cut the line on what you have drawn, inside that line or outside of it. This is relevant if you are fitting one cut object inside another, because one must be cut a little inside and the other a little outside. Trial and error my figure out this problem.

11. Save each 24" by 36" box with a drawing inside separately. It must be the only drawing in the file.

12. Save as a .dxf . In AutoCAD use the command DXFOUT to do this. In Illustrator, Export as a .dxf.

Advanced: A good technique to do this is to set up each sheet in a single drawing file, and then export them manually to individual files. Use the WBLOCK command. Type W in the command line. Using the dialog that appears, chose the objects to make into a new file, chose an origin point, and chose a name for your new file. Be sure to save as 2004 DWG or DXF.

13. Bring extra material, in case you make a mistake.

14. Make sure you explain to the monitor exactly what you want to do before you cut anything. She will help you with the setup if you are new to this.

Many of these rules are the same at other laser cutting facilities, such as the creation of many files and the marker for overlapping layers of material or cut and score files, but the bed size (24" by 36") may not be, and the constraints of the program that sends files to be cut (called Laserworks) may not be.

[edit] Examples of work that uses laser cutting:

The architectural firm Office dA. Look under projects, installations. Most of these are laser cut. www.officeda.com [1]