Laser Cutters

For the Full Spectrum Muse^, with a 45 Watt CO2 laser and 20x12" workarea:

"Power" Controls the frequency of laser pulses. "Current" controls the strength of each pulse, but is only active during vector cutting since the laser is modulated by the pixel darkness during raster operations.

Before cutting:

1. Switch on the power strip which also supplies power to the cooling pump and the air assist.
2. Ensure the water pump is running by squeezing the tube going from the bucket to the back of the laser. You should hear the sound of the pump change.
3. Check that everything is clear inside the unit
4. Power up the unit with the rocker switch in the back right.
5. Once the unit boots, press the button on the screen. It should slowly home.
6. Add your material, registering it in the upper left area on top of the cutting screen. Make sure it lays perfectly flat.
7. Loosen the lens mount on the cutting head and carefully slide it all the way up, then tighten, being very careful not to touch the mirror or lens.
8. Jog the cutting head over the material to the general area where you will work. Place the focus puck under the cutting head, on the material. Loosen the lens mount and allow the head to rest on the puck. Carefully tighten the mount, ensuring that it's not pressing the material down. Remove the puck.

After cutting, the fan will stay on. If you want to turn it if, it's under the gear icon on the front panel.

Open the lid, and do NOT move the material! Just hold it in place and try to remove a cutout or the outside edge. If it isn't fully cut, close the lid and run the job again, then decrease speed, increase power or passes the next time you that material.

Note 1: Woods and cardboard can catch fire. Always watch and have a fire extinguisher handy. Plywoods can vary because of the changes in the glue used to combine the layers. Individual testing is necessary. The gasses coming off the wood is often still combustible and will causes small explosions or "pops" which can blow up parts into the path of the cutting head.

Note 2: Setting the current to 10 will lightly mark the surface which will then allow you to verify the size and position without making super obvious marks on the part.

Note 3: On thicker materials, focus is critical to ensure a straight edge during the cut. Even with perfect focus, the edge will be slightly angled.

The web based RetinaEngrave 2.0 software has issues (which may or may not affect the Windows program version^ but it can not be used with the Muse):

• An object with a width set to 10" in the software, actually cuts at 9.92" wide.
• In the drawing section "Design View", units can not be edited by entering numbers. The number shown initially is inches, but if you change that number by dragging it up and down, the units change to hundredths of an inch. e.g. a box that is 10 (10") high will suddenly become 10 (0.1") high when you drag the units, and must be increased to 1000 (10.00") to regain the proper size. The only real way to use this feature is to make each thing a separate item and set the size in the main screen.
• DXF files may not be imported. More than that, there is NO list of what formats ARE supported! So far PDF and SVG appear to work.
  .re3 is the native file format in which projects are saved, and can be shared and re-opened.
  .ai (Adobe Illustrator) doesn't appear to work
  .bmp, .gif, .jpg, .jpeg, .png, .tif, .tiff, are bitmap formats, so only useful for etching
  .pdf, .svg, .svgz are vector formats.
• No file can be added except by drag and drop. E.g. there is no File / Open. The "Open File" icon opens an existing project saved internally. There is a File / Open in the "Design View" but it only accepts SVG, and it distorts the items. Update: in re3, you can only File / Import and not drag and drop.
• Save projects locally: They will randomly disappear from the internal storage.
• The Camera thing does not work at all under any circumstances that I can find.
• The "trace outline" icon on the front panel never works. You must do it from the web interface. If your connection isn't fast (e.g. old PC or wifi) then the tracking of the laser position will lock up your browser.

Most of these issues have been fixed in version 3 of the software.

Engraving requires some space to either side of the picture for the head to reach the correct speed before turning on the laser. Otherwise, the burn would be greater at the edges. This means that you can NOT engrave all the way to the edge of the workable area. Decreasing the speed (and power to compensate) of the settings for engraving can help to decrease this, but it is still significant.

Silk Screens: By setting a light fill color, and an even lighter stroke color on thin lines around each fill, you can produce an SVG or other graphic which will "Half-Tone Dither" to burn tiny holes in a thin plastic or other durable material. This can then be used as a silk screen or stencil. Fills with a saturation of 25 or less and strokes (line color) of 20 or less seem to work well at 250x250 DPI, with Blur Filter Raius at 7, Edge Enhance Threshold at 30 and Intensity Correction at 0. PET plastic lids from candy containers work ok, but are a bit thick for the paint. Manila folders produce a very nice screen, but are not very durable.

Solder Paste Stencils: Lower speeds allow sharper, more accurate fine details. Using laser transparency film at a speed of 10 and a power and current of 25 produces a Printed Circuit Board stencil that is usable down to about 0805 or perhaps 0603. Rows of very fine pins will not reproduce, but can be cut out in blocks and the pins will automatically align during reflow if the solder mask is good.

Maintenance:

• Use optical grade lens wipes to clean both sides of the beam combiner, all mirror surfaces, the focus lens, and the tube aperture. Optic surfaces may need to cleaned more often if cutting materials produce excessive residue (possibly daily).
• Clean fallen debris from the catch tray of the machine. Less excess material will reduce fire risk, and provide for better exhausting.Alcohol wipes remove pitch residue from wood cutting.
• Check the cooling water and replace if it starts getting slimy, or starts growing algae, or mold.

See also:

• https://youtu.be/W9n7gOlvy9w?t=671 Mustard will allow a CO2 laser to etch stainless steel.+
• https://www.engraving-supplies.com/plastics/laser-materials/foil-sticker.html Foil and stickers which can be laser engraved. There is a top color and an inner color which is exposed by the laser.
• http://colaser.org/ The laser cutter at San Diego CoLab.
• http://jeromeleary.com/ Make boxes, frames, gears, and slice objects for cutting.+
• https://deepnest.io/ Finds the optimal arrangements of parts in the smallest space.+

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