Laser Cutter

We have a Buildog.net 2.x Laser on site at Knox Makers. It is capable of cutting, engraving, and marking a number of different materials quickly and accurately when driven from CAD software such as Inkscape.

Buildlog 2.x Laser

See Also: Laser Hardware

The Buildlog.net 2.x Laser is an open source laser cutter/engraver. The usable work envelope is approximately 260mm x 500mm x 100mm. The machine uses a 40W CO₂ infrared laser to engrave/cut. Detailed information on it's operation is provided below, but the general theory of operation is as follows. Inside the laser cutter there is a very powerful CO₂ infrared laser that is bounced off of a few mirrors and is finally directed towards the material being cut or etched by a moving mirror and lens that focuses the coherent beam. These mirrors and lenses are gold coated to provide the best possible transmission of infrared energy.

There are two main variables that the laser uses to cut and etch: speed and power. When cutting, the laser power is increased and the speed is decreased so that the cutting beam spends a longer time hitting the material in order to cut though. While etching the speed is increased and/or the power reduced, this way the laser only removes a little material from the surface, leaving just the etching.

Usage

You must take the Laser Operation Class in order to have permission to use the laser cutter. The laser cutter is a very powerful, but also easy to break machine that requires some training to be able to use effectively and safely. Once you have taken the class, you will be added to the Knox Makers Laser Cutter Checkout List.

At this time, we do not plan to schedule the usage of the laser cutter. If usage is heavier than anticipated, we reserve the right to institute a scheduling system to be fair to other users.

If you see any troubles with the laser cutter, please submit a trouble ticket.

Materials

There are a wide range of materials that the Laser Cutter can cut, etch or mark - but some simply don't work (eg metals) and some are extremely hazardous to either humans or the machine itself. It is therefore imperative that you check the list of Laser Cutter Materials before attempting to cut materials that you have not worked with before.

Laser Cutter Settings

There has been some preliminary testing with common materials to generate a set of recommended values for speed and laser power: Laser Cutter Settings. These values have been included as defaults into our laser cutter Inkscape plug-in. The values should be acceptable for the listed materials, and can serve as a starting point for testing for other materials. The laser settings are internally limited to prevent damaging the laser, so feel free to experiment.

Beyond changing speed and laser power, do not attempt to change the configuration of the laser cutter. These settings are calibrated regularly by our Laser Cutting Czar and are not intended for users to change. Doing this messes up other people's work and it's NOT COOL. As with everything in the space, when you're done, leave things better than they were when you started. Changing settings could mean the laser is not right when the next person comes to use the machine.

Theory: How it Works

Inside the laser cutter there is a very powerful CO₂ infrared laser that is bounced off of a few mirrors onto a moving head and is finally directed towards the material being cut or etched by a moving mirror and lens that focuses the coherent beam. These mirrors and lenses are gold coated to provide the best possible transmission of infrared energy.

The infrared (IR) light that the laser cutter produces would blind you instantly if you were to look directly at it - and it's so bright that even you were only looking at the light reflected off the material that's being cut, it could still blind you. The IR light is also totally invisible. Fortunately, IR light doesn't pass easily through the window of the cutter that is made of a Polycarbonate plastic (which strongly absorbs light in those wavelengths). For this reason, if the lid (and the front panel) of the laser are not properly shut, then the IR laser will turn off automatically. The intense white light that you sometimes see when the cutter is operating is actually visible light that's being emitted by the material that the laser is burning off (it's literally 'white hot'!).

For carbon-based (organic) materials (like wood, paper, cloth and leather), you see the material being burned away and there may be black residue left behind. For plastics like Acrylic, the material is chemically decomposed by the laser and you don't see that white hot trail as it cuts. However, when the laser hits the metal grid beneath the material, there will still be bright flashes of light from that.

Making drawings for the Laser Cutter

See Also: Using Inkscape with the Laser Cutter

The recommended software path is to design your drawing in Inkscape, use the KMLaser bundle to export your drawing into gcode, then import the gcode to LinuxCNC which drives our laser cutter.

However, these are only conventions. The only requirements is that your design ends in gcode that is understood by our configuration of LinuxCNC. Laser Cutter Settings is a good reference with explanations of the values you will need to set in your gcode.

Raster Engraving

See separate Wiki article: Raster Engraving

External Links

Some helpful laser related links.

DIY Laser Cutters/Engravers

• Buildog DIY Laser <--- Knox Makers' Current Laser Cutter
• Lasersaur DIY laser cutter

CAM Software for Knox Makers Laser Cutter

• LinuxCNC - LinuxCNC
• LinuxCNC Config Setup - Stepper Config
• LinuxCNC INI Config - INI Config
• Currently Used Config

Laser Cutter/Engraver Safety Info

• Why you should not leave the laser unattended

General Laser Cutting/Engraving Info

• USL Materials Library

Cutting/Engraving Material Suppliers

• Jeffries Wood Works
• Inventables
• Regal Plastics
• Piedmont Plastics

Things to do with the Laser Cutter/Engraver

• Typeface for stencils
• Laser Origami
• Laser etched Chocolate
• Laser cut round stools
• Designing Laser-Cut Enclosures

Software Tools

• Nice Tabbed box maker
• Another Tabbed box maker
• Tuck box generator
• Tuck box python script

Misc

• Tissues for cleaning optics
• How to make snug joints in acrylic

Thanks

A very special thanks to ATX Hackerspace, whose hard work was the source and inspiration for a lot of the material included in our local wiki.