We have owned a Glowforge since their introduction and it has been a fun tool to work with. Here a few of my notes on cutting various materials, some acronyms and details which I found useful on this learning journey.
Terminology
- GF: Shorthand for “GlowForge”. There are two types of GF: basic and pro. They differ in the size of material that can be processed and the power of the laser.
- PG: Shorthand for “Proofgrade”™. PG material is provided by GF and is already calibrated for cut/score/engrave. The table below is for manual (not PG) material on a GF Basic.
- Laser: The ‘Pro’ version has a 45W CO2 laser. The basic (my version) has a 40W CO2 laser. The laser power impacts the ‘Power’ setting. (50% of 45W is not the same as 50% at 40W.)
- Speed: Value from 1 to 1000. 30% speed is 300. (The forums sometimes call this “zooms” as it zooms around.) NOTE: GF changed the scale during their beta period. If you see instructions prior to Aug 2017 that use very slow speeds (e.g., 15 for speed), then it’s likely the old scale. Using those slow speeds on the new GF will likely cause a fire.
- Power: Value from 1 to 100. 20% power is 20. With a 40W laser, 20% power is about 8W. (The forums sometimes call this “pews” as in “pew pew pew!” You might have someone say “I used 800 zooms and 50 pews.” The terms ‘zooms’ and ‘pews’ came about because GlowForge doesn’t provide units.) Keep in mind, power is not necessarily linear! And the intesity will drop with age (just like any light bulb).
- LPI: Lines per inch. Mostly for graphics/engraving. Defaults to 225. Use higher value to prevent rastering. At around 300LPI, the engraving dots overlap. 225 is good for draft, but will raster. 340 has no noticable rastering on most materials. At super high 1355LPI, you might see numberical error in the rastered graph that looks like a pixel shift. I’d avoid anything over 600LPI.
- Flashback: When the laser cuts through, it may create sparks off the crumbtray’s metal. These sparks can create burns, or flashback, on the back of the material. Lowering the amount of power (or increasing speed) reduces flashback.
- Kerf: The laser burns away material. The kerf is the gap created by the laser. More power creates a wider kerf. Some materials melt or burn back (e.g., foam or paper), creating a wide kerf.
- On really hard material, just assume the kerf is 0.002″ (0.05mm).
- In general, kerf on PG hardwood is about 0.002″, and 0.002-0.022″ in general.
- PG Medium Maple has a kerf around 0.008″.
- PG Draftboard has a kerf around 0.002″ (use 0.05mm – 0.06mm; 0.05 is barely loose; 0.055mm is good).
- PG Acrylic has a kerf around 0.002″ (0.05mm).
- Zebrawood, Purpleheart, and other really hard woods have a kerf around 0.002″ (0.05mm).
- For inlays: Take half the kerf from the outside material (small hole) and half the kerf from the inside material (fill hole). Increase the inside/fill material’s size by this amount. If the outside material is flexible (e.g., wood) and you want a really tight fit, increase the size of the inside/fill material by another 0.001″. For inflexible (acrylic, hardwoods), you might add 0.0005″ for a really snug fit.
- Inlay: Acrylic in Medium Maple: Increase acrylic by 0.020. Using 0.015 can be finger-pressed in but also pops out easily. Using 0.017 can still be popped out. However, if 0.020 doesn’t fit in the first time, then first put in 0.017 and then pop it out. That will stretch the hole just a little so the 0.020 fits tightly and will never come out.
- Inlay: Acrylic in Medium Draftboard: (TBD) Increase acrylic by 0.025. The kerf from draftboard is larger than a hardwood like medium maple.
- Cut: Cuts through material. Uses a solid laser to vaporize material. Slower speeds create more control (rounder edges), but fast speeds are fine for straight lines.
- Score: Vector lines that don’t cut. For example, if 30% power cuts the material, then 15% will score it. AFAICT, this just cuts the power to 50% or 25%. If scoring burns at corners or where circles start/stop, then use a slower speed and lower power. Typically scoring under speed 150 (with appropriate power) won’t over-burn at corners.
- Engrave: Etching. Rather than using a solid laser, it appears to pulse “pixels”. For soft material, engraving can cut! To cut, try higher LPI (more overlap) and/or slower speed (more overlap). You don’t always need to up the power to make it cut; just make it go slower and overlap more. Keep in mind, engraving is always slower than cut/score.
- Dither vs Variable power. When engraving grayscale images, you can either dither or use variable power. Some materials can show a gradient intensity (e.g., foam, paper, wood) — use variable power. Others only show the presense of the lasered area; this is usually materials that don’t cut (metal, glass, plastics, etc.) — use dithering.
- Painter’s Tape: Blue painter’s tape is can be applied to cover material. If the material burns (e.g., wood, paper, cardboard), then smoke can discolor the surface. A layer of Painter’s Tape stops the smoke from discoloring the surface. However: When it gets heated, the quick-release glue can become like cement on paper. If the laser burns the tape (resulting in wide black areas around the cut), then it may not remove from paper. Use low power when using blue tape. Blue tape also has a thickness (0.005″); it requires a minimum of 1000/3 to engrave through the tape.
- Acrylic: There are two types of acrylic: extruded and cast.
Materials
Power levels assume a 40W CO2 laser.
| Material | Thickness (inches) | Cut (speed/power) | Score (speed/power) | Engrave (speed/power/lpi) |
| PG | ||||
| PG Medium Cherry Hardwood | 0.125″ | 189/Full | 195/12Double sided will have holes that go all the way through where corners meet. | 450/28/450 |
| PG Medium Red Acrylic | 0.125″ | 150/Full | 125/11 | 1000/Full/270 |
| Acrylic | ||||
| Two-Tone AcrylicInventiblesTake plastic off! | 0.125″ | 150/100 | 125/10 | HD: 800/50/675 SD: 300/16/450 (same as PG Red HD) Lower than 675 loses resolution and pixelates. |
| Foam | ||||
| Material | Thickness (inches) | Cut (speed/power) | Score (speed/power) | Engrave (speed/power/lpi) |
| Rubber Stamp | ||||
| EVA Foamboard (generic, thin)Michaels, Hobby Lobby “Fun Foam”Use magnets to hold it down! Very light material will move when the fan blows. | 2mm, 0.076″ | 1000/50 or 500/50May need 1-2 passes.Slower for smoother edges.Melts about 0.025″ of material; kerf of about 0.025″.Even from the same vendor, each batch and color may have slightly different properties. Don’t remove from laser unless you know it is cut (permits redoing the cut if it needs another pass). | 500/5Power 5-10 burns through at start/stop.Power 1-5 is faint.On colored foam, may leave dark spots at start/stop. | 1000/10/340 to 1000/20/340, variable power.Use 340 LPI to avoid raster lines.Some material colors result in discoloration; power 1-10 varies the coloring, but 10-20 does not. Power 10-20 just makes it deeper. For grayscale images, use variable power with a max power of 10.For large discolored surfaces, there may be a textured “foam” pattern. |
| EVA Foamboard (Red) | 2mm, 0.076″ | See generic. | See generic. | See generic.Discolors to a high-contrast dark red.Variable power from 1-10. |
| EVA Foamboard (Yellow) | 2mm, 0.076″ | See generic. | See generic.Burns black at start/stop of score paths. | See generic.Discolors to a slightly darker yellow; low contrast.Variable power from 1-20. |
| EVA Foamboard (Green) | 2mm, 0.076″ | See generic. | See generic. | See generic.Discolors to a high-contrast dark green.Variable power from 1-10. |
| EVA Foamboard (Blue) | 2mm, 0.076″ | See generic. | See generic. | See generic.Discolors to a high-contrast dark blue.Variable power from 1-10. |
| EVA Foamboard (White) | 2mm, 0.076″ | See generic. | See generic. | See generic.Zero discoloration; remains white embossed pattern.May look cool if you fill the embossed area with water colors. |
| EVA Foamboard (generic, thick) | 6.35mm, 0.25″ | 200/60 | 500/25 | |
| EVA FoamboardAmazon Tiles / TNT Cosplay / Harbor Freight ROLLS.Reference | 4-6mm | 275/100, 2 passes | 1000/60/125, 1 pass | |
| EVA FoamboardFoamiesReference | 2-3mm | 275/80, 1 pass | 1000/60/125, 1 pass | |
| Neoprene foamHazardous gas! Chlorine | 0.85mm / 0.033″ | 500/65Kerf is about 0.25mm / 0.01″ | Unknown | Unknown |
| Paper and Cardboard | ||||
| Material | Thickness (inches) | Cut (speed/power) | Score (speed/power) | Engrave (speed/power/lpi) |
| Chipboard, darkArtist hardboard | Height 0.15″ | 240/full 2 passesTry 180/full | 500/full | 500/50, 340dpi |
| Cardboard corregated | Height 0.16″ | 200/60 | 500/5 – 500/10 | 1000/10 – 1000/20 340dpi |
| Cardboard box lid | Height 1/2″ max | Do not use ‘cut’ mode because it burns; use engrave mode to cut.Engrave 300/65/225 for thick linesEngrave 300/40/340 for thinner linesUse blue tape to make sharper lines. | Do not score; use engrave. | 1000/50/340, Use blue tape to make sharper lines.800/20/270 (no tape needed!) |
| Cardboard, cereal box(Use to test veneer) | Height 0.025″ | 300/50 | 500/5 – 500/10 | 1000/10 – 1000/20 340dpi |
| Printer Paper, 24lbMagnets to keep from blowing. | 0.005″ | Cut 200/5 (may require a tug to separate)Engrave at 800/20/270 and it barely will burn through.Engrave 800/15/270 for fine lace cuts.Engrave 800/15/340 LPI for more cutting. | 500/2 | 800/10/270 works really well. The burn looks golden on white paper. (Power between 12 and 14 may burn through parts since paper isn’t perfectly even at that fine resolution.) |
| Paper, Cardstock | 0.005″ | Try 200/15 – 200/20Paper may burn/discolor.Try Engrave at 300/650/340 since it will likely burn through. | Do not score; use engrave. | 1000/6/340 to 1000/20/340 |
| Rice paper envelopes | 0.01″ | Try 500/3, 2 passesPut cardboard between the layers to only cut the front. | Do not score. | TBD: Do not engrave. Or use 1000/1/225 and see what happens. |
| Leather | ||||
| Material | Thickness (inches) | Cut (speed/power) | Score (speed/power) | Engrave (speed/power/lpi) |
| Leather (veg tan)Tandy Leather | 0.1″-0.15″ | 170/100 (a little too strong, chars+smoke)Clean charring with light water and sand edges(Maybe try 170/50 or 170/80)If possible, engrave first, cover in blue tape, then cut. | 250/2Dark line, no smoke/char | 1000/15-30/195 (very readable; no smoke/char)Visually, 15 is a little lighter than 25.1000/20/270 (high-res; no smoke/char)Photos: variable power, 1000/20/195variable 1000/25/170 also works, but you can see pixels |
| Wood Particles | ||||
| Material | Thickness (inches) | Cut (speed/power) | Score (speed/power) | Engrave (speed/power/lpi) |
| Bamboo, chopsticks | 0.185″ | TBD | TBD | 225/25/340Bamboo burns really dark! |
| Baltich Birch, Craft/Popsicle Stick | 0.085″ | TBD | TBD | 600/80/340Burns really dark! |
| Plywood | TBD | 250/40 | 500-600/40-50/340 | |
| CorkHobby Lobby, Michaels | 0.2″ (0.1995″)Thicker is fine for engraving. | 200/50, 4 or 5 passesCork is really hard to cut.Slower than 150 causes fire.Faster than 250 doesn’t cut deep.Too much initial power causes fire, charring, and smoke stains. Keep it at power 50 or less.Even 200/50 4-passes barely cuts all the way. (Still need to cut/pull apart.)Cutting over an etched area causes fire and smoke staining. Cut first, then etch!The problem: Cork is a great insulator. First pass burns the cork and carmelizes the top of what is left. 2nd pass takes more power to get past hard carmelized area. 3rd pass needs even more power.Unless absolutely necessary, don’t cut cork. | 300/50 | 1000/10/225, dithered.Works really well: just burns where the laser hits, no smoke stain. No visible rastering. (No masking tape needed.) |
| Hardwoods (Zebrawood, Purpleheart, Yellowheart) | 0.12″ (3mm)Thicker is fine for engraving. | 180/fullNo thicker than 0.12″/3mm; the laser cannot penetrate any further. Even repeated passes won’t go further than 4mm. Too many passes will char. Kerf is 0.002″.If you need to cut thicker wood, use a saw. | 500/1 leaves a very fine line.500/50 is a deep line | 800/50/450 removes 1/32″ — can be used repeatedly up to 1/8″. There will be charring.800/20/450 is great for drawing.For variable depth, use 800/25/450. |
| Wood (Solid) | ||||
| Material | Thickness (inches) | Cut (speed/power) | Score (speed/power) | Engrave (speed/power/lpi) |
| Pine | Any | TBD | TBD | 450/80/125450/50/225Grain ridges stand out.Power 50-90 (50 is too light, 100 is overkill) |
| Other | ||||
| Material | Thickness (inches) | Cut (speed/power) | Score (speed/power) | Engrave (speed/power/lpi) |
| Pencil | 0.29″, round | TBD | TBD | Most pencils have 2 layers of paint.1000/8 450dpi goes through first layer.1000/25 goes through all paint to the wood.Beware of the curvature! You only have about 0.1″ height change before the laser fails to focus. On a round pencil, that makes the usable canvas about 0.14″ high x length of pencil. Aligning long text on the pencil is difficult! |
| Stone, Lapidary | TBD | Does not cut. | Does not score. | Try 800/89 225dpi |
| DenimRef | Medium weight, height 0.015″ | TBD | Does not score. | Try 15/1000 – 125/1000 |
| Denim | Light weight | TBD | Does not score. | Try 8/1000 |
| Plastic pill bottlesPlastic “2” ♴ HDPE (e.g., white pill bottles)Plastic “5” ♷ PP (e.g., transparent amber bottles) | 0.05″ or thicker | Does not cut.Just melts and may burn.Fire hazard and messy. | Does not score. | Try 1000/10, dithered.Reportedly no smell.Smooth surfaces should become rough. Transparent should become opaque. |
| Plastic credit cards; hotel key cards | DO NOT USE!PVC plastic emits corrosive and poisonous gas. | |||
| Glass | TBD | Does not cut. | Does not score. | Try 1000/10, dithered.Try 100/850/340, ditheredCoat with a thin layer of dishsoap or masking tape to prevent surface fracturing. The idea is to help dissapate heat. |
| MetalRef | Any | Does not cut. | Does not score. | Coat with yellow mustard or a paper towl moistened with vinegar (wet, not dripping). Try 250/full, 340 LPIAcid + Laser = Engraving. Leaves a “dark marking” where the laser hits. |
| Stainless steel etching | Any | Does not cut. | Does not score. | Try 1000/20, dithered.Use 3 coats of dry moly lube. |
| AcrylicHome Depot | 0.093″ | 200/fullKerf 0.006″ (0.16mm) | TBD | TBD, dithered. |
| LaserTile.com | 0.315″ or 0.3″ | Does not cut. | 500/50 | 500/50 at 225LPI – 445LPI, dithered.Vendor claims 800/100If too dark, use less power or faster speed.If too light, use more power or slower speed. |
| SiliconHard drive platters | DO NOT USE!Reflects CO2 laser. This will damage the laser cutter. May injure you if you are standing near the laser cutter. | |||