Laser Cutter Notes

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Revision as of 16:30, 5 April 2011 by VDX (talk | contribs) (power source and output-power control)
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Laser Cutter

Release status: unknown

Beamy.jpg
Description
turnkey or DIY laser-cutter toolheads
License
Author
Contributors
Based-on
[[]]
Categories
CAD Models
none
External Link
none


RepRap Research/Writeups

Bright-VikBot or a good name.

Background

See Laser_Cutter/Background

Description

Discussion: http://forums.reprap.org/read.php?70,13836,14061#msg-14061


Cost Estimate

- 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).

Components

Laser Light Sources

~45 W sealed CO2 laser ...


1 watt pigtail diode laser with optical head (focus ~50 microns):

1Watt Diode-laser with focussing head


5 watt pigtail diode laser with 4xLM317-driver atached and lighting on a beam-indicator without optics:

5Watt-Diodelaser with 4xLM317-driver


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:

5Watt-Prototype1 5Watt-Prototype1


'real blue' 445nm-diode with 1Ampere current and roughly 1Watt output power. - left = focussed beam, middle = burning without filter, right = UV-filterplate:

445nm von Vorne kl.jpg 445nm - 1Watt ohne Filter.jpg 445nm - 1Watt mit Filter.jpg

1. Laser-source:

- CO2-lasertube ... sealed (RF) or 'naked' glass-tube

- diode-laser ... best with atached glass fibre (=pigtailed)

- ...

beam-feeding optics

2. beam-feeding optics:

- CO2: - mirrors

- diode-lasers: - glass fibre and/or lenses and mirrors

- ...

focussing optics

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:

Pilot-Laser

power source and output-power control

Main article: Bright Light Circuit

4. power-source:

- 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)

LM317 parallel

- a 5xLM317-driver with switching MOSFET:

5xLM317

- 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:

5xLM317

- ...


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:

XY-pulsegenerator

- calculating the needed power relative to moving speed of the laser focus

- ...

air jet

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?


Usage

CO2-laser cutting acrylic:

CO2-cutting encoder-disc


Diode-laser:

- cutting:

VDX-RepLas2.jpg Hase celtic.jpg

- brazing / hard soldering:

hard soldered gold-paste


Multi-Diode-Laserhead:

- 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 ...

Capacity/Specifications

Requirements

Power
Nitrogen tank or clean dry compressed air.

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)

Laser-goggles


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:

Laserrauchabsorber.jpg


When using inert (and other) gases in an enclosed room you have to test for leakage or monitor the oxygen-concentration in the room.

External links