The cut sheets
1 sheet. 1220 × 2440 mm, 18 mm plywood. Total cut path 29.2 m.
Machine time for the whole unit: about 1.1 h best, 1.9 h typical, 4.4 h slow. Based on reported 120 W-class diode speeds, multiple passes at 18 mm. One timed scrap cut will replace this.
A commercial CO2 flatbed is about 0.9 h in the sourced case. That number is an assumption, not a cut on this machine.
Sheet 1 carries a fit-test coupon: cut it first and try the tab in the slot before you cut the rest. Hover or tap a part below to light it in the model.
Build stages
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1
Cut the sheet(s) about 195 min (3 h 15 min)
Run the fit-test coupon first (slot = tab + 0.1 mm), then cut 1 sheet(s) from the DXFs (CUT layer): 29 m of path, 18 parts. Inside-out order, air assist on.
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2
Remove char and sand about 72 min (1 h 12 min)
Brush the char off every edge, 120 then 180 grit. Ease the TOP front and side edges (the visible top slab); sand the slot ends flush later, after glue.
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3
Dry fit one shelf about 30 min
For each shelf: stand the two END plates, drop the FRONT and HANGER between them, then fit BOTTOM underneath and TOP on top of all the tabs. Check the box is square and the cavity is clear for the Z-bar.
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4
Pre-finish about 65 min (1 h 5 min)
Stain or seal the inside of the box and the HANGER rear face lightly, then finish TOP/BOTTOM faces. Mask the tabs and slots so the glue still bonds.
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5
Glue-up (Titebond III) about 60 min (1 h)
Per shelf: glue the ENDs into BOTTOM, add FRONT and HANGER, then seat TOP over every tab. Clamp with cauls across the width. Wipe squeeze-out.
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6
Screws as clamps about 24 min
6 #8 x 1-1/2 in screws (3.0 mm pilots cut in the BOTTOM): from the underside up into the END plates, between the tabs. The TOP is glue and tab only, so the top face stays clean; clamp it with cauls while it dries.
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7
Fit the Z-bar cleats about 45 min
Screw the shelf half of each aluminum Z-bar (lengths 24/24/18 in) to the rear face of the HANGER with #8 x 5/8 in screws (shorter than the 18 mm plate, so they cannot show). Mount the wall half level into studs (2 screws per stud, 16 in centers), then hang the shelf from above.
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8
Hang, test, pack about 25 min
Hang, then load-test each shelf with 10 kg at the front edge. Flat-pack in one 1.0 x 0.3 x 0.1 m box.
About 8 h 36 min for all 8 stages.
Materials and hardware
18 mm (3/4 in) birch or Baltic-birch plywood, 4 x 8 ft (1220 x 2440 mm) x 1. Thickness 18 mm. 1 sheet.
Glue: Titebond III, about 3 oz.
Finish: stain or water-based poly, 2 coats (about $10).
| Hardware | Qty | Each | Line |
|---|---|---|---|
| #8 x 1-1/2 in wood screws from model | 6 | $0.06 | $0.36 |
| Aluminum Z-bar French cleat pair (wall half + shelf half), lengths 24/24/18 in about $0.55 per inch per pair (assumption); laser cannot cut the 45 deg bevel | 1 | $36.30 | $36.30 |
| #8 x 5/8 in screws for the shelf-half bars | 18 | $0.04 | $0.72 |
| Wall screws / stud screws for the wall-half bars #10 x 2-1/2 in; into studs | 12 | $0.15 | $1.80 |
| Wood plugs / filler | 1 | $2.00 | $2.00 |
| Hardware total | $41.18 |
Screws counted from the model: #8 x 1-1/2 in × 6.
Profit estimate
Estimates and assumptions. Every dollar figure on this page is a planning estimate, not a quote and not a promise. Sheet price, hardware, fees, labor, and machine wear are assumptions. Machine time is based on reported 120 W-class diode speeds, multiple passes at 18 mm. One timed scrap cut will replace this.
Diode machine time
These three columns are the same unit at the mid selling price. Best, typical, and slow are the diode estimates. Based on reported 120 W-class diode speeds, multiple passes at 18 mm. One timed scrap cut will replace this.
| Best | Typical | Slow | |
|---|---|---|---|
| Machine time | 1.1 h | 1.95 h | 4.41 h |
| Cost per unit | $153.05 | $154.50 | $158.68 |
| Gross margin | $56.95 | $55.50 | $51.32 |
| Gross margin % | 27.1% | 26.4% | 24.4% |
| Net after fees and labor | -$19.05 | -$20.50 | -$24.68 |
| Gross profit per machine hour | $51.77 | $28.46 | $11.64 |
| Net profit per machine hour | -$17.32 | -$10.51 | -$5.60 |
Commercial laser (assumptions)
These columns are assumptions, not a cut on this machine. ASSUMPTION. Sourced case: 300-600 W CO2 flatbed, single pass at ~600 mm/min (vendor 480-720), 60 m/min rapids, 5 min/sheet, $8/h operating cost. What-if cases: a machine 10x / 20x faster than the diode mid cut+travel time (not sourced for 18 mm ply).
| Commercial CO2 (assumption) | What-if 10× (assumption) | What-if 20× (assumption) | |
|---|---|---|---|
| Machine time | 0.9 h | 0.25 h | 0.17 h |
| Cost per unit | $158.38 | $153.18 | $152.54 |
| Gross margin | $51.62 | $56.82 | $57.46 |
| Gross margin % | 24.6% | 27.1% | 27.4% |
| Net after fees and labor | -$24.38 | -$19.18 | -$18.54 |
| Gross profit per machine hour | $57.36 | $227.28 | $338.00 |
| Net profit per machine hour | -$27.09 | -$76.72 | -$109.06 |
Selling price, at the typical diode time
| Low price | Mid price | High price | |
|---|---|---|---|
| Selling price | $130.00 | $210.00 | $320.00 |
| Cost per unit | $154.50 | $154.50 | $154.50 |
| Gross margin | -$24.50 | $55.50 | $165.50 |
| Gross margin % | -18.8% | 26.4% | 51.7% |
| Net after fees and labor | -$92.50 | -$20.50 | $78.50 |
| Machine hours | 1.95 h | 1.95 h | 1.95 h |
| Gross profit per machine hour | -$12.56 | $28.46 | $84.87 |
| Net profit per machine hour | -$47.44 | -$10.51 | $40.26 |
ESTIMATE: 1.9 h (low-speed case 4.4 h, best case 1.1 h) of machine time per unit for 29 m of cut path in 1 sheet(s) on a 120 W diode, 18 mm plywood. Machine time, not material, is still the limit on profit per hour, but a single test cut on scrap will replace this range with a real number.
All dollar figures are planning ESTIMATES / ASSUMPTIONS, not quotes, not guaranteed. Sheet prices: 4x8 ft 18 mm birch plywood $70-110, basic plywood $55-75 (assumption). Machine time uses a sourced RANGE for a 120 W diode on 18 mm ply (low 120 / typical 300 / high 600 mm/min effective, i.e. after multiple passes; taken from reported speeds for a 120 W-class diode); ACMER publishes no 18 mm ply feed rate, so none of it is measured on this machine. Machine wear/electricity $1.70 per machine-hour (assumption). Labor valued at $25/h for the "after labor" line only. Marketplace fees 10% (assumption, e.g. Etsy-style).
Where the price band came from: My estimate: single floating shelves sell for about $25-$60 at commodity level and $60-$120 handmade (Etsy; a survey of similar pieces for sale "considered and not picked" because commodity pricing is low). A 3-shelf stepped set, finished, with the cleat hardware included, is priced as a set. Low = 2 short unfinished shelves, high = 5 long finished.
Try your own numbers
Change the sheet cost, hardware, selling price, labor rate, or machine time. Finish ($10.00) and packaging ($10.00) stay put. Machine wear follows the machine-time choice: $1.70 per hour on the diode estimates, $8.00 per hour on the commercial assumptions. Fees stay at 10% of the selling price. Labor uses the planned 2.2 h at the rate you type.
Still an estimate. Based on reported 120 W-class diode speeds, multiple passes at 18 mm. One timed scrap cut will replace this. The commercial rows are assumptions, not a cut on this machine.
Parameters
These are the knobs for a custom order. The model on this page uses the defaults. Stay inside the limits.
| Parameter | Default | Limits |
|---|---|---|
| Width | 900 | 400-1200 mm |
| Shelves | 3 | 1-5 |
| Depth | 220 | 190-300 mm |
| Shelf height | 80 | 76-110 mm |
| Shelf pitch | 300 | 200-500 mm (>= height + 120) |
| Step back each tier | 150 | 0-300 mm (shortest >= 300) |
| Thickness | 18 | 17.5-19 mm |
| Slot clearance | 0.1 | 0.0-0.2 mm |
Safety notes
- Mount the wall half of each cleat into studs only (not drywall anchors alone); level it before hanging.
- Rated target 10 kg per shelf at a 220 mm depth, UNVERIFIED - load test each shelf at 15 kg before selling; the rating falls as depth grows.
- Keep heavy items (books, appliances) on a conventional bookcase, not on a floating shelf.
- Not a children's product (no CPSIA testing); do not use as a climbing aid.
Unverified / to test
- Machine time is an estimate (120 W diode on 18 mm ply, sourced range, not measured on this machine); cut time and profit/hour depend on it.
- Z-bar cleat load rating and the pull-out strength of the shelf-half screws in an 18 mm HANGER face are not tested; the checks.txt load-path line is a rough hand estimate.
- Z-bar profile dimensions differ by supplier (the 24 mm recess and 44 mm cavity are sized for a typical 1 in bar and must be confirmed with the bar you buy).
- The wall bar is aluminum from a hardware store: the laser cannot cut a true 45 deg bevel in ply, so ply-only cleats are not offered.
- The cost model charges one whole 4x8 sheet but this set fills only 39% of it (offcut not credited). Nesting 2 sets per sheet (area allows it; not nested here) would cut mid cost to about $110 and lift mid gross margin from 26% to about 48%. The Z-bar hardware (about $36) is a large share of cost. As modeled, the low price band is below cost.
- Price band is my estimate, not a market quote.
Downloads
Meadowlark Models. Numbers on this page are estimates. Machine time is based on reported 120 W-class diode speeds. One timed scrap cut will replace it.