A through-cut is one pass that has to succeed everywhere at once.
Engraving forgives a bad patch — the surface is a little lighter there and the piece is still usable. A cut does not. It either severs the board along every millimetre of the path or it does not, and the one spot where it did not is the spot that tears when you lift the sheet. Almost everything below is about making the whole path behave the same way.
Through-cutting solid wood, plywood, MDF and veneer — parts, shapes, lettering and sign components.
Thickness and species, focus, air assist, speed, how flat the sheet sits, and where the part is held.
The one thing worth knowing before anything else
On wood, more wattage buys speed — not much more thickness. A bigger tube roughly halves the time a 1/4″ sheet takes; it does not turn a machine that tops out around 1/4″ in a single pass into one that severs 3/4″ hardwood cleanly. The thing that actually runs out first is bed size: a shop that buys 4×8 sheets and owns a machine that cannot take one is cutting every sheet down by hand before the laser ever sees it. Size to the stock you buy.
A CO₂ laser with a bed that takes your sheet stock whole. On wood the bed runs out long before the wattage does.
Size a CO₂ System| Material | Power % at 70 W / 105 W / 155 W | Speed | Thickness |
|---|---|---|---|
| Balsa wood | 60 / 55 / 50 | 25 mm/s | 1/8″ |
| Bass wood | 60 / 55 / 40 | 25 mm/s | 1/8″ |
| Birch wood | 80 / 70 / 65 | 10–20 mm/s | 1/4″ |
| Birch plywood | 85 / 75 / 70 | 10–20 mm/s | 1/4″ |
Read the power column as a wattage trade: the same cut needs a lower percentage on a bigger tube. On the multi-speed rows the faster end pairs with the higher wattage. The two birch rows are Boss’s, not a typo of ours — the birch-wood and birch-plywood charts are both internally titled “Birch Wood Cutting” and carry different values, so we list them by source file rather than guess. If the difference matters for your job, confirm with Boss.
Reading those numbers as an answer about power
The question people arrive with is “how many watts do I need.” The chart answers it sideways, and more usefully. Every row is cut by all three wattage tiers — 70 W, 105 W and 155 W all get through 1/4″ birch. What changes is the percentage each one has to run at, and therefore how hard the tube is working and how fast the job finishes. A 70 W machine cutting 1/4″ plywood at 85% is near the top of its useful range with nothing held back; a 155 W machine doing the same cut at 70% has headroom, and will still be doing it happily on the two-hundredth sheet.
So the honest translation is: wattage is a duty-cycle and speed decision far more than a capability one. Buy for the thickness you run most days, not the thickest sheet you have ever managed to get through.
Where the published chart stops — and what we will not print
Boss’s cutting figures cover 1/8″ and 1/4″, single pass. Thicker hardwood is cut on these machines every day — slower, at more power, often in two passes — but Boss publishes no chart beyond 1/4″, so there is no first-party number for us to give you and we are not going to invent one. The same goes for kerf width: Boss publishes no kerf figure for wood, and it moves with species, thickness, focus and lens anyway. Measure it on your own stock — it takes one test cut.
The four rules underneath every number in that table
- Refocus for every new material. The focal point sits a fixed distance below the lens. A board thicker or thinner than your last job puts the work off-focus, so the beam arriving at the surface is wider and weaker — the single most common reason a setting that worked last week does not cut through today.
- Stay between 5% and 95% power. Below roughly 5% the tube will not fire at all. Above 95% you are spending tube life for very little extra cut. If a job needs more than that, it needs a slower speed or a second pass, not a higher number.
- Air assist is part of the cut, not an accessory. The air stream blows the burning plume out of the kerf so it cannot shield the beam or film the lens. Cutting without it is how a clean setting turns into a charred one. Air assist clears the kerf; the exhaust clears the room — two jobs, both required.
- Start on a scrap of the same board. Not the same species — the same board. Boss ships engraving, cutting and scoring test files on the machine’s USB drive for exactly this.
Kerf: measure it once, then design around it
The beam removes material, so a cut path takes a narrow channel of wood with it. Your part comes out slightly smaller than drawn and the hole slightly larger — by half the kerf on each side. Ignore that and a 10 mm peg will rattle in a 10 mm hole every single time.
Finding your number takes one cut: draw a square of a known size, cut it in the stock you actually use, and measure the finished square with calipers. The difference between drawn and measured is the full kerf; half of it is the offset you apply per edge. Do it again whenever you change species, thickness, lens or focus, because all four move it. This is why we publish no kerf table — a number measured on someone else’s birch is not a number about your birch.
Small parts and lettering
The failure mode with lettering and fine shapes is usually not cut quality, it is the part moving or dropping mid-job. Once a piece is severed it is loose on the slats, and anything still being cut around it now has a moving target. A few habits fix most of it:
- Cut interior features before the outline. Counters in letters, holes and inner details go first, while the part is still anchored in the sheet. The outline is always the last thing that happens to a part.
- Watch the loose-centre problem. The middle of an O, A or 4 drops the moment it is severed. On a honeycomb bed it usually stays put; on wide slats it falls through and can scorch on its way past the beam.
- Hold the sheet flat. A bowed board changes its own focus across the bed — cut through on one side, not quite through on the other. Weights or magnets at the corners cost nothing and remove a whole category of failure.
- Very fine stems are a stock problem. If a serif or a 1 mm bridge keeps breaking, the answer is usually thinner or denser stock, or a slightly heavier typeface — not a different setting.
Cuts most predictably when the grain is even and the resin content low. Knots are local density spikes — the beam that cut the board either does not get through the knot or over-burns around it. Resinous species char more and smell more.
Cuts well and stays flat, which is why so much laser work is done in it. The variable is the glue: more smoke, heavier char, and any internal void burns unevenly wherever it sits under the beam. Laser-grade ply is void-free ply, and that is what you are paying for.
Uniform in every direction, so it cuts with no grain surprises at all — but it is the most glue-heavy of the three. Expect the most smoke, the darkest edge and the strongest smell. It also takes paint beautifully, which is why signage shops keep using it anyway.
The hard line, which matters more here than anywhere else
PVC and vinyl never go in a laser. They release hydrogen chloride, which becomes hydrochloric acid in contact with moisture — it corrodes the machine and it is dangerous to breathe. That rule reaches the wood bench because so much sheet stock is faced or edged with it: “wood-look” laminates, melamine-faced board and iron-on edge banding are commonly PVC. Treated and painted lumber is an unknown coating until someone produces the safety data sheet. If nobody can name the material, do not run it.
A CO₂ laser cuts wood by burning through it, so combustion residue is not a defect — it is the process leaving evidence. Two different marks get confused with each other, and they have different fixes:
- Soot is loose smoke residue deposited on the face of the sheet around the cut line, usually as a grey-brown halo. It sits on top of the wood.
- Char is scorched wood in the kerf wall itself. It is not residue, it is burnt material, and you cannot wipe it off — you either prevent it or sand it back.
Masking prevents the first one almost entirely. A layer of low-tack transfer tape over the face takes the smoke halo with it when you peel it, and it is the cheapest quality upgrade available on a wood bench.† For char, the fix is at the machine and in this order: raise air assist, raise speed, then drop power to the least that still severs. Adding power to a char problem makes it worse, every time.
The smell is the same story one day later. Freshly cut wood carries absorbed smoke, and porous stock — MDF and plywood most of all — holds far more of it than dense solid timber. It fades with air: parts left spread out in a ventilated space give it up over hours to days, where the same parts sealed in a box the moment they came off the bed keep it. Nothing about it is a machine fault, and it is another argument for masking, for good extraction, and for not bagging work while it is still warm.†
† Masking, cleanup and de-smelling are settled shop craft, not Boss-published procedure — Boss publishes no cleaning method for laser-cut wood. Test any solvent, abrasive or finish on a scrap of the same stock first; species and pre-existing finishes react differently, and some methods remove more than soot.
Wood cutting FAQs
Questions people ask about cutting wood.
The ones that come up once someone is past “can it cut wood at all.”
QHow much laser power do you need to cut wood?
Less than most people expect, and the chart is the proof. Boss publishes cutting settings for 70 W, 105 W and 155 W CO₂ tiers, and all three get through the same materials — 1/8″ balsa and basswood, 1/4″ birch and birch plywood. The difference is the percentage each has to run at: 1/4″ birch plywood takes 85% on a 70 W machine and 70% on a 155 W one. So wattage buys you speed, headroom and an easier life at volume rather than a thicker cut. Pick the tier from how many hours a day the machine will run and how fast you need parts off it, then pick the bed from the sheet size you buy — that is the dimension that actually limits most wood shops.
QWhat changes when I cut MDF or plywood instead of solid wood?
Glue. Both are engineered boards held together with adhesive, and the adhesive burns differently from wood — more smoke, a darker edge and a stronger smell, with MDF the heaviest of the three on all counts. In exchange you get something solid timber cannot offer: uniformity. MDF has no grain to engrave unevenly and no knots to stall a cut, and good plywood stays flat across a big sheet. The one thing to buy carefully is plywood quality: cheap ply has internal voids, and a void under the beam burns out into a ragged pocket that no setting prevents. Laser-grade plywood is simply void-free plywood, and on a job with two hundred parts it pays for itself. Watch for faced boards — melamine and “wood-look” laminate are often PVC, which must never go in a laser.
QHow do I clean soot and burn marks off laser-cut wood?
Separate the two problems first, because only one of them is cleanable. Soot is smoke residue sitting on the surface around the cut — it wipes, lifts or sands off. Char is burnt wood inside the kerf wall; it is not residue and nothing will wipe it away, so it has to be prevented at the machine or sanded back afterwards. For soot, the real answer is to stop it landing: mask the face with low-tack transfer tape and peel it after the cut, and the halo leaves with the tape. For parts already marked, light sanding with fine grit along the grain works on most solid stock; a barely damp cloth lifts loose residue but raises the grain on porous wood and can spread soot into it, so test on a scrap first. For char in the kerf, go back to the settings: raise air assist, raise speed, drop power to the least that still cuts through. Boss publishes no cleaning procedure, so treat all of this as shop craft and prove it on scrap before you try it on a finished piece.
QHow do I cut wood letters and small shapes without losing the details?
Almost every lost detail is a movement problem, not a cut-quality one. The moment a piece is fully severed it is loose on the bed, and anything still being cut nearby is now cutting a part that can shift. Sequence the job so interior features — the counters inside letters, holes, inner details — are cut before the outline, so the part stays anchored in the sheet as long as possible. Expect the centres of letters like O, A and 4 to drop free the instant they are cut; a honeycomb bed usually holds them, wide slats let them fall. Keep the sheet flat with weights or magnets, because a bowed board cuts through on one side of the bed and not the other. And if a thin stem or bridge keeps snapping after the cut, that is a stock decision rather than a settings one — thinner or denser material, or a slightly heavier typeface.
QWhy does laser-cut wood smell, and how do I get rid of it?
Cutting wood with a CO₂ laser is controlled burning, and the parts come off the bed holding absorbed smoke. Porous stock holds far more of it than dense stock, which is why MDF and plywood smell strongest and a tight hardwood barely does. It is not a machine fault and it is not permanent: spread the parts out somewhere ventilated and it fades over hours to days. What keeps it is bagging or boxing the work while it is still warm. Three things shorten it — masking the face so less smoke reaches the surface, good extraction so the plume leaves the cabinet instead of settling back onto the sheet, and air assist set high enough that smoke is blown out of the kerf rather than driven into the cut wall. If a finish is going on anyway, sanding the faces before finishing removes most of what is left.
QWhy did my cut go through on one side of the sheet but not the other?
Nine times out of ten the sheet is not flat, or the bed is not level. The focal point sits a fixed distance below the lens, so if the board rises or falls even slightly across the bed, part of it is out of focus — and an out-of-focus beam is wider and less intense, which is exactly the beam that almost cuts through. Weight or clamp the corners, check the bed is level, and refocus for the current material thickness rather than trusting the last job’s setting. If the sheet is genuinely flat and it still happens in the same region of the bed every time, that points at the beam path rather than the material, and it is worth a call to Boss Technical Support rather than another adjustment of power.
Sources
Every power, speed and thickness figure above is transcribed from Boss’s own BL2-T83 CO₂ material settings charts (70 / 105 / 155 W tiers) — first-party Boss data, not industry averages. The focus rule, the 5–95% power limits, the air-assist requirement and the USB test files come from the Boss HP Series User Manual. The birch-chart discrepancy is a quirk in Boss’s own source PDFs, recorded here rather than resolved. Items marked † — masking, cleanup and de-smelling — are settled shop practice with no Boss-published procedure behind them, and are labelled as such. Every setting is a starting point: wood varies board to board, so prove it on a scrap of the same stock.
Still deciding?
Tell us what you cut, not what you own.
Sheet size, the species and thickness you run most often, and how many parts a day. That is enough for a specialist to name the right bed and wattage — including when the answer is less machine than you were expecting.