Information about using a laser cutter.
- Instructables guide: How to Use a Laser Cutter
- How do I determine the optimal laser parameters for my material?
- there are several modes that process the output from the application you’re printing from before it goes to job control
- eg for rubber stamp making, photo engraving, etc
- for all modes, other than relief mode, engraving will be done as “on”/“off” pulses at the set power level
- many of the driver modes dictate how colours or shades of grey are converted (dithered) to very high resolution bitmaps (image with just “black & white” or “on & off”)
- if you want maximum control, or follow many online guides, you will adjust your image in an image app such as gimp, photoshop, coreldraw, or photodemon (which has many dithering options!) and dither it to black and white in that app. In this case, In this case DO NOT use the “photo enhance” mode. It will re-dither your already black and white image!
- Interesting modes:
- “layer” mode: appears to bin the image into several sub images, one per layer. Each subimage is a bin of a range of shades of grey. E.g. if there are 256 shades of grey, and 4 layers, it will generate 4 images, each with 64 shades of grey. Each of these sub-images will the be dithered into black & white and engraved. Each layer can have a Z offset, hence changing the focus.
- “relief” mode: instead of dithering the data into black and white, the laser power at each pixel will be set proportional to the shade of grey. The power scale appears to be the power setting selected and not full scale.
- the driver has both PPI (pixels per inch) and DPI settings.
- PPI is the actual number of pules per inch.
- DPI is what the output will be internally rendered to
- for best results, the PPI should be the same as or a multiple of the DPI
- description of the other driver settings
- ATX Hackerspace list of materials
- Calibration for materials
- Need to make something like this: https://www.thingiverse.com/thing:728579/#comments
- Remember: use the ‘relief’ mode that uses grayscale to directly control power, rather than using dithering
- This Trotec page has instructions and a usable template image
- A more detailed material calibration guide from Trotec
- Epilog’s tips and pointers
- Sawmill creek: Laser engraving denim aprons
- QBotics: Science with denim (engraving denim)
- Darker engraving- several techniques
- trying to “caramalize” the wood; think of a poker tool
- different woods will react… differently
- “Low and Slow”: reduce power and speed
- “Max PPI”: wood can only “display” so many PPI. Higher PPI wil lead to multiple laser bursts hitting the same “pixel” -> more burning
- “defocus”: go ~+0.5mm out of focus with regular engraving settings. Can be done manually or by tweaking the Z-offset in the materials database. Results maybe a little fuzzy. Can be really cleaned up by a low power cut pass around the engraved objects.
- above hints found from here, here, and here.
You may be putting damp things in the Laser.
BE EXTREMELY CAREFUL TO NOT GET THE LASER WET!
- engraving a photo, see photo section below
- making micro-fractures; may need to control heating so the surface doesn’t break down into shards, or just shatter
- minor “sharding” - scrub with brillo pad afterwards
- cheaper glass works better; crystal and better glass includes metals, and these block/stop the effect
- use a film of dish-soapy water and/or a damp, single layer piece of paper; people use paper towels and or newspaper
- can try transfer tape; doesn’t need water (Julian has seen less success with this, but may not have been the right kind of transfer tape.)
- may need to spritz during the engrave
- cover the area to be engraved with the wet material or transfer tape. Make sure there are NO bubbles
- High power, medium speed, lower PPI (pulses) and lower DPI in source image is best
- goal is less continuous heating, more “spot blasts”
- there are debates re Stucki or ordered half-toning. May want to use B&W in the driver and do the half tone in Photo Demon/Gimp/etc
- don’t engrave solid black- adjust to 70-80% (so it will be dithered, and not apply continuous power.)
- Refs: https://www.troteclaser.com/en-ca/knowledge/do-it-yourself-samples/glass-bottle-laser-engraved/, https://www.troteclaser.com/en-ca/knowledge/tips-for-laser-users/glass-engraving/, https://electronics360.globalspec.com/article/10505/eight-tips-for-laser-etching-glass, https://www.youtube.com/watch?v=Y5v9pBVopFU
- engraving a photo, see photo section below
- Use minimal power; don’t want to generate dust
- Power 45, speed 100, air-assist off (Mike was also using a Speed 300 80W)
- may need edge (power) compensation
- above from Mike Clark
- Forums on Sawmill creek- lots of great information, and a very helpful community. Not just lasers- CNC and engravers too!
- Sawmill creek: removing burnt edge from laser cut wood
- Tips and techniques for sharpening an image- including USM (Unsharp Mask)
- Unsharp Mask: How Do You Actually Use That Thing?
- for transparent materials, probably need to invert the image; do it sooner in the process
- tonal mapping (levels) gives more control than brightness/contrast; can use an “S-Curve” to bump up blacks, and drop whites.
- Unsharp Mask (USM) - maximum, radius 8-10 seems to be peoples typical settings
Box Templates and Generators
- Big list of box generators: http://www.instructables.com/id/The-Ultimate-Guide-to-Laser-cut-Box-Generators/
- Parametric Flexbox by bdahlem
Material Cutting Templates
- 5’x5’ baltic birch plywood sheets:
Open the image in a new tab to see the template full size.