Do I need air assist and fume extraction for a laser on my router, and what are the fire safety rules?

What air assist does

Air assist blows a stream of air at the burn point. Opt Lasers says it helps clear smoke, reduce residue, protect the optics and improve edge quality. J Tech Photonics says its nozzle keeps smoke off the lens and gives cleaner engraving and more effective cutting.

Air assist settings published by J Tech Photonics

• Regulated pressure between 2 and 15 PSI. J Tech warns against using too much pressure.
• A small pump is enough for engraving. For cutting, J Tech recommends its larger pump. An aquarium style pump can stand in for a compressor.
• Do not use air assist on flammable materials such as foam and thermoplastics.
• Keep the feed at 10 inches per minute or faster to prevent flare-ups.
• Turn the air off as soon as the cut is finished, and always be present while it runs.

Fire and eye safety published by Sienci Labs

1. Never leave the laser unattended.
2. Keep a fire extinguisher or other fire suppression within reach.
3. Everyone in the room wears laser safety glasses rated for the laser. Sienci supplies OD 7+ glasses with its 7 W head.
4. Work in a well ventilated space, with fume extraction or an open door or window.
5. Switch the laser off when it is not in use.
6. Take the dust shoe off. Sienci warns that dust shoe bristles can melt or catch fire under the laser.

Materials that must never go under the laser

Sienci lists PVC, ABS, vinyl and fiberglass. J Tech explains why PVC and vinyl are banned: they release chlorine gas, which ruins the optics and corrodes the machine. See the entry on what a diode laser can and cannot cut for the full list.

Pro tips

• Onefinity's setup guide says to remove the router bit and collet before running the laser.
• A router bed is covered in fine wood dust and offcuts. Vacuum the area before lasering so stray chips are not sitting next to the burn.
• Record the air setting with your power and speed results. Opt Lasers lists air assist as one of the conditions that changes a test result.