Universal Laser Cutter

The laser cutter is a potentially dangerous machine. It is very easy to start fires and it can also produce dangerous fumes (e.g., chlorine) if used with improper materials. Everyone must receive training prior to use of the laser cutter. The cutter must also remain under constant supervision while in use.

Never cut PVC, or other chlorinated plastics (Lexan and PC board are also strongly discouraged).  PVC in particular will give off chlorine gas, which is not only highly corrosive to the machine, but also dangerous for any nearby people.

Never leave the machine unattended while it is running, regardless of how long you need it to operate.

If the lab phone rings – pick it up. It is likely to be John DiFrancesco (difran@media.mit.edu), seeing you through the online camera broadcast, and figuring you could use some help. You can always also e-mail him with any questions

If fire starts inside the machine go through the following steps. Open lid to stop laser from working, and turn the machine off. Put an acrylic sheet over the burning material to smother the fire. Push up on the blast gate to stop air flow (if you can reach it). Call 100 if all else fails, or you feel you are in danger.

Our 100 watt laser cutter can cut acrylic, wood, paper, foamcore, among other materials.  It can also etch vectors and raster images into these materials, as well as glass, stone, slate, etc. Our laser cutter cannot cut metal. There are two basic types of actions we can perform using the printer: one is a vector cut, meaning it cuts all the way through, and the other is a raster cut, which etches the surface, but does not go through all the way.

Software

CorelDraw or cad.py are the available programs installed on the computer that is connected to the laser cutter. Use the link for useful guidelines. Suggestions for some tested settings can be found in a wordpad file on the desktop.

Using the Laser Cutter

Turn on the machine and the air assist line

use the orange switch to turn on th emachine (lower right side). You will hear the main fan unit coming on. Make sure the air assist valve is on (to the left of the cutter).

Clean and focus the lens

The lens should be removed from the machine (with the three thumbscrews) and checked for material accumulation at the beginning of each cutting session.  Pull out the lens and mirror. Clean them with a cotton swab and the cleaning material found opposite of the computer. Accumulated gunk may get burned when the laser is used and will crack the lens. Lenses are >$200 a piece, so it's important to be careful about this.

The laser cutter must be focused before use.  This is done using the plastic focus tool, and the Z adjustments of the laser cutter. You want the shoulder of the lens-house to sit on the white focusing tool, which should be placed on top of the piece you are about to cut. Also, make sure you are using the 2” focusing tool for the 2” lens. On the machine, press the Z button (far right). Use the up and down buttons on the machine to raise or lower the platform. For a finer movement up/down hit the check mark (or select) once, then use the arrows again. Hit the Z button once again when you are done.

Set the origin

The laser cutter origin is at the top-left [CorelDraw] or bottom right [cad.py] and is configurable through the laser cutter menus. The origin is frequently moved during typical cutting sessions, to best utilize the remaining material from a piece of stock.  Be sure to check the origin before beginning your cut, as the system retains origin settings from previous runs -- even if the machine has been powered off in the interim. As a part of registration, it's good to do a draft unpowered cut.

Draft (unpowered) cut

With the cover open, hit the green start button on the machine, and watch the head trace the drawing with a red beam. It will first trace all rasters, then the vector lines. You can always stop it in mid-action by hitting the ‘pause’ button.

Make sure the cutter will execute the current job you sent by clicking on the "fast-forward" or "next file" button. When everything seems good to go close the cover and hit start again. Keep your attention on the machine, in case anything goes wrong. While it is working, you can always hit ’pause’ – it will stop, and will start from the same point upon hitting ‘resume’.

Once the job is done, wait at least half a minute before opening the cover for the fumes to at least partially clear from the chamber.

Clean up and turn the machine off.

Misc. tips and tricks

It is strongly encouraged to do early cutting runs in corrugated cardboard or masonite.  It's cheap, easy to mark with a pen and hack with a knife and environmentally sound.

Light materials (e.g., cardboard, thin plastic, paper, and vellum) generally need to be taped down to the laser cutter bed with masking tape. Otherwise, vibration and the air displacement of the moving cutter head will move materials during cutting.

It's worth noting that the laser cutter beam has a finite width, which changes both as a function of the material, and as a product of its depth within the material.  The cut width will be wider at the upper surface than at deeper locations within the material.  This can significantly influence the fitting of laser-cut parts, especially for press-fit joins.

Small quantities of translucent 1/4 and 1/8 inch acrylic stock should be available in the hallway, but individual users are basically responsible for purchasing their own stock if different what is in the shelf.

Materials:

Cherry wood is available at Pearl in the modeling section. 1/8" acrylic is available at J. Freeman, Inc (800-841-9442). Get 4 by8 foot sheets and have them cut to size. McMasterCarr also has a selection of acrylics.