Session 7: Laser Cutting & Engraving
Session 7
Laser Cutting & Engraving
The Router Can't Write a Button Label
Your cabinet's buttons need labels: P1, START, letters a few millimeters tall. The Genmitsu's smallest bit is 3.175 mm across, about as wide as the letters themselves.
Every inside corner it cuts is round, too. Fine lettering and sharp corners need a tool much thinner than any bit.
A Beam Instead of a Bit
The Epilog Fusion Pro 48 focuses a laser beam to a tiny spot and burns the material away where it lands. Nothing touches the work, so nothing has to be clamped against a cutting force.
Its bed is 48 × 36 inches, bigger than the Genmitsu's, but it cuts only thin sheet. Thick panels still go to the routers.
Two Ways to Use the Beam
Two Ways to Use the Beam
Raster engraves. The beam sweeps back and forth like a printer and burns in every filled shape. It marks the surface; it never cuts through.
Vector cuts. The beam follows a line once, slowly enough to go all the way through the sheet.
You Choose Cut or Engrave
The shop's laser runs from Epilog Pulse, in a web browser. Every shape in your file gets a process, and you pick it from a menu: Engrave, Cut, or Off.
One rule you can't get around: Pulse cuts only shapes drawn as outlines. Set a solid, filled shape to Cut and Pulse refuses: "All shapes in a cut process must have strokes." A plate drawn as a filled block can be engraved, but never cut free.
Speed and Power Trade Off
Two settings matter most. Power is how hard the beam burns. Speed is how fast it moves. Slower and stronger means deeper.
Too little and a cut stops partway, so the part stays stuck in the sheet. Too much and the edges char, or the wood catches fire. Today you find the line between them.
A cut has a third setting, Frequency: how often the laser pulses. Leave it where the shop's settings chart puts it.
The Real Hazard Is Fire
A vector cut puts a lot of heat into one line. Epilog's own guidance is blunt: never run the laser unattended. Materials you've cut a hundred times can still flare up.
Air assist on whenever you cut. The tray cleared of scraps, because loose bits are kindling. You know where the extinguisher is before the job starts.
Some Materials Wreck the Machine
PVC and vinyl give off hydrogen chloride when they burn. Epilog warns it can do irreversible damage to the laser, and it's toxic to breathe.
Plastics don't come labeled. Kydex looks like any other sheet and contains PVC. Only materials on the shop's approved list go in, and an unknown sheet doesn't go in at all.
The Door Is Part of the Safety
With its door closed, the Fusion Pro is rated a Class 2 laser product: the beam stays inside the machine.
That rating depends on the door. Never block it, prop it, or reach in while a job is running.
A Second Sign-Off, Same Standard
Like the routers in Session 4, the laser is certified per machine. Nobody runs it alone until they've watched the demo, run a job under supervision, and gotten every spot-the-problem item right.
Today
- Watch the demo and write the laser's startup card
- Spot the problem in six laser setups
- Your group's cut test: one speed, one result, added to the class table
- Your supervised run, for the sign-off
Next Time
Session 8: Toolpaths, Offsets, Step-Over & Step-Down
Back to the routers, where the bit's width is the problem you have to plan around.
'F' → Fullscreen
Build
Nobody runs the laser alone today. Every job happens with your instructor at the machine.
Step 1: The Demo and the Startup Card
Your instructor runs one job from start to finish. On your sheet, write the laser's startup sequence in order, in your own words, from turning it on to taking the finished part out. You'll use this card every time you use the laser.
Step 2: Spot the Problem
While other groups are at the laser, find the problem in each setup. Say what could happen, then the fix.
- A student starts a cutting job, then goes to the printer to pick up a handout. "It's only two minutes."
- A group brings a clear plastic sheet from home to cut a phone stand. Nobody knows what plastic it is.
- Air assist is switched off because it's noisy. The job is cutting plywood.
- Small offcuts from the last three jobs are still lying in the tray under the cutting grid.
- A cut didn't go all the way through, so a student opens the door while the job is still running to check.
- A button plate is drawn as a solid, filled rectangle, and the group sets it to Cut so it comes out of the sheet.
Step 3: The Cut Test
Your instructor gives your group one speed. The file is the same for every group: a small square drawn as a cutting line. The power and the material are the same too. Only the speed changes.
- Your instructor opens the file in Pulse. The square appears under Processes as a Cut, and its Speed is set to your group's number. Power and Frequency stay the same for everyone.
- Before you run it, predict: will your square cut all the way through, partway, or barely mark the sheet?
- Run it with your instructor, watching the whole time.
- Push gently on the square. Record whether it fell out, held by a few fibers, or didn't come through at all. Look at the cut edge: clean, brown, or black?
- Add your result to the class table on the board.
When every group has run, find the fastest speed that still cut all the way through. That's the setting to use for this material, and the reason a shop keeps a settings chart.
Clicking a process's name opens a menu where every shape can be switched between Engrave, Cut, and Off. Text and filled shapes arrive as Engrave; outlines arrive as Cut.
Step 4: Your Supervised Run
Each of you does one step of your group's job with your instructor watching: loading and placing the sheet, focusing, sending the file, starting it, or taking the part out once the job is finished.
Checkpoint
Before you leave, confirm:
- Your startup card is complete and in order
- All six spot-the-problem setups have a hazard and a fix
- Your group's cut test result is on the class table
- You did your step of a supervised run
Reflection
Answer these on your own. Reflections are individual, even when the rest of the session was team work.
- Both the router and the laser could cut out a small button-label plate with 5 mm lettering. Which would you choose, and what about the job decides it?
- The router and the laser both have a "never leave it running" rule. What goes wrong on each machine if nobody is watching, and why is it a different kind of danger?
Submit
Submit your startup card, your spot-the-problem answers, your cut test prediction and result with the class's threshold speed, and your reflection.