Laser Cutter Notes
- 1 RepRap Research/Writeups
- 2 Background
- 3 Cost Estimate
- 4 Components
- 5 Usage
- 6 Capacity/Specifications
- 7 Requirements
- 8 Cutting speed
- 9 Health and Safety
- 10 Similar projects
- 11 External links
See the Laser Cutter Working Group@forum.reprap for discussion.
- comercial 'naked' diodelaser with [email protected] and 0.1mm atached glass fibre: ~230 Euros (in quantities above 5 pcs).
- turnkey-system with [email protected], a visible red pilot-laser and jack for the glass fibre: ~1000 Euros (in quantities above 5 pcs).
Laser Light Sources
- Different laserdiodes:
1 watt pigtail diode laser with optical head (focus ~50 microns):
- Complete modules:
5 watt pigtail diode laser with 4xLM317-driver atached and lighting on a beam-indicator without optics:
complete 5 watt pigtail diode laser-module with 4x or 5x LM317-driver, MOSFET, microcontroller, armored tube and an optic head - prototype on the left, V2 on the right:
'real blue' 445nm-diode with 1Ampere current and roughly 1Watt output power. - left = focussed beam, middle = burning without filter, right = UV-filterplate:
- CO2-lasertube ... sealed (RF) or 'naked' glass-tube
- diode-laser ... best with atached glass fibre (=pigtailed)
2. beam-feeding optics:
- CO2: - mirrors
- diode-lasers: - glass fibre and/or lenses and mirrors
3. focussing optics:
- CO2: - Germanium- or ZnSe-lens for CO2-laser ... concave mirror is possible too
- diode-lasers: - 'normal' optical lenses
3.1. Embedding a Pilotlaser as guide or beam-indicator:
power source and output-power control
- Main article: Bright Light Circuit
- CO2: - mostly monolithic PS, good when below 40 Volts for RF-CO2-lasers, 'naked' and DIY-CO2-tubes need above 1000 Volts
- diode-lasers: - constant-current-driver (e.g. more LM317 in parallel)
- a 5xLM317-driver with switching MOSFET:
- modified driver with 2xLM317 with 1Ampere each and 3xLM338 with 2, 2, and 2.6 Ampere for free combinations from 1 to 8.6 Amps:
5. output-power controller:
- CO2: - embedded in RF-CO2-lasers - mostly TTL-input capable of switching the laser output with some ten kHz
- diode-lasers: - current-modulation and/or PWM-switching for diode-lasers until some kHz
- diode-lasers: - AOM (AcoustoOpticalModulator) switching until some hundred kHz
6. controlling the output-power:
- generating geometrically defined pulses from the XY-clocks of the CNC-controller:
- calculating the needed power relative to moving speed of the laser focus
While not strictly necessary, many laser cutters have a blow a jet of air at the point being cut. Is it better to use (a) relatively cool room-temperature air, or (b) hot air?
CO2-laser cutting acrylic:
- brazing / hard soldering:
- similar to an inkjet-printer, where many nozzles ar aligned in an array to print many dot-lines synchrone, you can align multiple diode-lasers in an array to process parallel lines simultanuous.
With falling prices of laserdiodes it should be possible to build a head with 8 hating/burning spots in a line with a distance of 5mm (diameter of typical small collimator-lenses) between them (or less, when arranging in a zigzag-array) in a DIY-range below 1000 Euros.
With a software separating the processing data for the single lasers you can speedup the time per sheet along with the count of lasers ...
- Nitrogen tank or clean dry compressed air.
The primary factors affecting cutting speed v are laser beam power P, the material being cut and its thickness h. The dependence of v on P and h is approximately proportional, i.e. severance energy P/hv is approximately constant for a fixed material and cutting process. Severance energy can be thought of as the laser beam energy needed to make a cut of 1 mm2 area (i.e. 1 mm cut length × 1 mm thickness). Note that 1 Watt power is 1 Joule of energy per second, so a 36 W laser should cut 3 mm acrylic sheet (P/hv=1.2 J/mm2) at the speed of about v = P/h / (P/hv) = (36 W) / (3 mm) / (1.2 J/mm2)=10 mm/sec.
|Material|| Typical severance
| Min-max severance
Health and Safety
Laser-goggles are essential when working with lasers!
This laser-goggles have blocking ranges of 700-1100nm (for diode-lasers and NdYAG) and 10600nm (for CO2-lasers)
Fumes and vapours are extremely toxic and carcinogenic!
You can absorb the toxic vapours by exhausting the fuming area through a charcoalabsorber - e.g. the disc-shaped filters often used in deep fat fryers, or filtering units for soldering ...
Common laser-fume absorbers are really big parts but much more capable than absorbers for soldering vapours:
When using inert (and other) gases in an enclosed room you have to test for leakage or monitor the oxygen-concentration in the room.
There are some similar projects to create an Open Source laser cutter, some of them already shipping devices:
- LaserSaur (see Bill of Material, G-Code driver,Arduino Shield, and Application)
- LaosLaser (see http://wiki.laoslaser.org/)
- how to build a Router Laser CNC using some part from old printers