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project:cchs:laser_cutter:usage_details

Laser Cutter Usage - Detailed

There are two other laser cutter pages you might want:

If you want to know how to do fancy tricky things with the laser cutter, read on:

Design Tools

Any tool that can create DXF files can be used to create content for laser cutting.

Inkscape

Detailed video presentation by Zac: http://www.youtube.com/watch?v=FZUQ-BFJji4

  1. Once you have your design ready to go, choose File→Save As or File→Save A Copy
  2. in the File Type dropdown choose “Desktop Cutting Plotter (AutoCAD R14 ) *.dxf”
  3. In the next dialog box the default settings are OK, but make sure “mm” is selected for units.

If the DXF is missing some parts when opened in CamBam, do a Path → Object to Path on those objects in Inkscape before saving. Some Inkscape shapes (like Polylines) don’t seem to come over at all.

Blender

See blender.

Design Rules

Bed Maximum Dimensions: 440x280mm

Maximum material thickness: 6mm (thicker possible with careful planning, work flipping, etc)

Inverted Y Axis: The laser cutter cuts inverted on the Y axis, For cutting this is not a problem (unless you are using a material with different surface textures on each side), however for engraving you will want to mirror any text or features in your design on the Y axis.

Notes

The laser does not usually cut perfectly at a right angle. As the material you cut gets thicker, this will affect the quality of your job. Keep this in mind when determining the material thickness you need.

If you are using an existing piece of material with previous cuts in it, in many cases it’s easier to modify the location of your work during processing with CamBam than to override the home location of the laser cutter. This is due to the fact that the laser cutter includes an offset for it’s homing position, as compared to the home position of the material.

Material Choice

Materials Available At CCHS

CCHS now has a range of Acrylic stock for purchase by members. Its located in the upper left pidgeon hole, closest to the laser cutter.

Typical sheet size is 360 x 235mm (so it'll fit in either blue or black laser cutter). However some sheets may be a bit longer or wider. Pricing is the same (per sheet), regardless of size.

When purchasing please deposit the appropriate cash in the “drinks kitty” located near the fridge and vending machines.

1.5mm Clear, $5

2.0mm Opal (whitish), $6
2.0mm Black Opaque, $6

3.0mm Clear, $10
3.0mm White Opaque, $10

3.0mm Black Opaque, $10
3.0mm Dark Grey Translucent, $10
3.0mm Red Translucent 102, $10
3.0mm Amber Translucent, $10
3.0mm Blue Translucent, $10
3.0mm Funky Purple 775, $10
3.0mm Red Opaque, $10
3.0mm Blue Opaque, $10
3.0mm Silver Mirror, $10 (cut with mirror facing down!!)

We're looking at purchasing some laser bamboo and perspex led (side lighting) product. We'll add to the range as we go.

Materials from other Plastics Suppliers

ttps://plyco.com.au/collections/all/products/quadro-poplar?variant=36895700176

https://plyco.com.au/collections/all/products/eucalypt-laserply?variant=39956906000

(Plyco has heaps of other plywood options, different thicknesses etc.
The above are two common examples used with laser fabrication.)

http://www.lidotell.com.au/sheet-and-tube
Preston.

https://perspexcuttosize.com.au/contact-us
Collingwood.

I used Plasticraft in Huntingdale a few years ago, with happy results.
Their website appears to be down?
https://www.yellowpages.com.au/vic/huntingdale/plasticraft-pty-ltd-13318486-listing.html

http://www.plasticcenter.com.au/
Cheltenham. I've used them in the past.

http://www.regencyplastics.com.au/contact-us/
Kilsyth.

http://www.acrylicsonline.com.au/
Based in Brisbane, you can mail-order stuff.

http://www.plasticsforindustry.com.au/contact
Keysborough.

http://plasmac.com.au/contact/
Huntingdale

Identifying Materials

If you are unsure about a material, ask first (either in the space or on the mailing list.)

Always be mindful of any protective films on plastics and materials that might be made of a hazardous material and should be removed.

MSDS

All materials should have an MSDS (Materials Safety Data Sheet) that can be referenced. The MSDS should list all the necessary details and precautions that need to be taken when processing or using the material in any way, whether that is laser cutting or milling, handling procedures, and any notes on toxicity and combustion byproducts.

A supplier of the material should be able to provide the MSDS (usually on their website, or on the manufacturers website). If it’s a generic material, then the MSDS should be the same as that of other brands of the same material. It should be noted that many materials are “blended” and that in many cases the amounts in the blend vary widely with manufacturer and/or application (ABS is a perfect example), so care should be taken to find the right MSDS for the material you are using. Also, many manufacturers create versions of materials that contain extra additives to give it slightly better/different properties (eg: higher melting temperature, better UV resistance) that can affect how you need to process the material, or if you should be processing it at all.

As a basic rule of thumb for plastics, if it burns black, then it it is unlikely to be cuttable in the laser. At the very least, soot will get on the lens causing all sorts of issues. It is also likely to be toxic.

Known good materials

Materials that are NOT okay to use

  • PVC or any vinyls/pleather/etc (by products: chlorine gas)
  • ABS (by products: hydrogen cyanide, other nasty stuff)
  • Polypropylene (by products: ketones and formaldehyde)
  • MDF, Plywood & Particle Boards (by products: formaldehyde)
  • Cellulose acetate (needs more investigation into byproducts)

Maybe (needs more research)

Some techniques for possible materials identification can be found here.

Other spaces' list of materials for laser cutting (check their facts, though!)

Operation

See also First time Laser Cutter Howto. Never operate the laser cutter without someone experienced on hand who knows what you are doing.

Power On and Safety

FIXME : These steps were last edited December 2013, can someone familiar with the laser cutter please confirm they are current then remove this marker?

Power On

  1. Locate the main power switch on the lower right hand side of the laser to power the laser cutter.Toggle the power switch to the ON position.
  2. Confirm you are aware of the location of fire extinguisher and fire blanket (Above laser to left, on wall)
  3. Confirm laser Interlock Switch (Black toggle switch) is in the OFF position
  4. Check water cooling system
  5. Water tank (Esky, Check water level)
  6. Water pump (Submersible , inside esky)
  7. Water pipes (Check opaque section for air bubbles)
  8. Water temperature (displayed on LCD, Laser is protected and will not cut if water temperature exceeds 35 degrees C)
  9. Check extraction fan on wall is operating, This ducts gases to the external ventilation vent.

Before Cutting

  • Have you read the MSDS (Materials Safety Data Sheet)? Do you know that what you are cutting is safe?
  • Check mirror guide and gantry are free and clear of any obstructions ? (Such as the Z height adjusting chuck.)
  • Check laser bed for any foreign material.
  • On your first run, confirm the gases are being drawn to the left of the laser housing and drawn into the external venting system.
  • Check air flows towards the left hand side of the laser cutter into the ventilation system.
  • Observe that there is air moving near the laser cutter head inside the unit, this indicates the air assist is keeping the mirrors free of dust.
  • It is usually a good idea to do a “dry run” first, by running your G-code on the machine with the Interlock Switch turned OFF (laser turned off). As the outside is usually cut first, this can help if you are not sure the material you have is the right size for the job.

* DO NOT LEAVE THE MACHINE UNATTENDED. Issues can escalate very quickly, so you need to be on-hand at all times to supervise what is going on.

Power off

  • Locate the main power switch on the lower right hand side of the laser to power the laser cutter.Toggle the power switch to the OFF position.
  • Ensure the Interlock Switch (Black toggle switch) is set to OFF.
  • All scraps are put in the bin, or trimmed for use by others.

G-Code

Custom G-Code operation is in use. Of most relevance is that:

G0: Jog move at fixed rapid pace (something like 10,000 mm/min)

G0 X0 Y0: Go to origin (X:0, Y:0)

M3 or M4: Turn Laser on Full

M5: Turn Laser off

M(3,4) S(0-255): Turn laser on with intensity of S (255=full on, 0=off). Eg. M3 S128 = Turn laser on at half power.

M5, M107 - Turn laser off. This should be in your header and footer of every design. It should be very near the start and end of your G-code file. Check it is there. Now check it again.

M114: Output current position

G28: Go to home position (X: -12, Y: -14)

Marlin firmware GCodes (non-standard and different from Sprinter) Linuxcnc also has a good page on gcode at http://linuxcnc.org/docs/html/gcode.html

! M3/4/106 S0 DOES NOT EQUATE TO M5/M107. Use M5/M107 always ! G92 - reset the laser’s 0 point. Move the Laser to your new X,Y position and enter the command “G92 X0 Y0” to set that as the current “home”.

These can be utilized automatically in CamBam by use of post-processing script found here: GRBL_laser.cbpp.

Only use this with engraves as there was a known issue with other path generation styles (pockets, etc.).

Useful CamBam settings

(Some basic settings are listed at in the Howto also.)

Pocket

Common settings: To obtain a frosting effect on the surface of acrylic, Cut Feedrates of 2400 (or higher) and Spindle Speed of 50 is recommended.

4 Parameters are required to be populated for a valid machine operation. Target Depth: As CamBam is expecting a milling operation, not a laser, a valid depth must be populated in this field, it should always be equal to single Depth Increment and be a negative number. The default is -0.4 Cut Feedrate: This parameter maps to the movement speed of the laser. 300 to 12,000 are typical speeds used. Spindle Speed: This parameter maps to Laser Intensity/Power 50 through to 255 are valid. Tool Diameter: This parameter maps to the width of the laser beam. Testing has shown this to be approximately 0.4mm.

Engrave (or Cut)

Common Settings: To Cut Material, Slow speed (300) and Full Power (255) is recommended.

2 Parameters are required to be populated for a valid machine operation. Cut Feedrate: This parameter maps to the movement speed of the laser. 300 to 12,000 are typical speeds used. Spindle Speed: This parameter maps to Laser Intensity/Power 50 through to 255 are valid.

project/cchs/laser_cutter/usage_details.txt · Last modified: 2017/10/06 13:14 by 58.107.167.134