Goal: To build a hobby grade CNC laser cutter that will cut materials up to ¼ inch thick with a work area of 48” x 24”. The machine must be safe, reliable and accurate to 1/40". It will be build using commonly available off the shelf parts and materials. Budget is $2000.

After researching the existing machines, I’ve narrowed my design options down to two possibilities.

Design Option #1: A moving XY table with stationary vertically mounted laser and optics
Advantages:
  • No Mirrors Required
  • Minimal alignment required
  • No power loss on reflections
  • Less ways to fail

Disadvantages:
  • Wastes space
  • Footprint is more than twice the work area
  • Long rails are likely to hurt accuracy and add expense
Novel Idea:
Use something like a large salad bowl mounded upside down over the laser head and attached to a vacuum source to exhaust fumes and filter IR. This would save the expensive building a large cover as required by design option #2.

Design Option #2: Flying Optics design with a horizontally mounted laser parallel with x axis. Work is stationary. Beam is reflected onto work surface by mirrors moving on a lightweight gantry.
Example: Emissions Technology
Advantages:
  • Moving parts are fast and light
  • Compact footprint
  • Shorter more precise rails could be used
Disadvantages:
  • Requires at least 2 mirrors
  • Requires 4 mirrors for the most compact footprint
  • Requires precise alignment
  • Has serious failure modes resulting in smoke and fire
  • Wastes some power on each mirror

Option #1 is technically easier to implement and is far less clever that Option #2.
Option #2 is more practical, but will require more R&D to be made safe and reliable.

Right now I’m leaning towards option #2 and am looking at ways to implement it with only 2 or 3 mirrors. This seems like the way to go. It will be a slight improvement on the emissions technology approach.

If anyone else has build one of these or is planning on building one, I'd like to hear your thoughts.