Size the box from the machine's extreme envelope plus 6 in [150 mm] of clearance on every moving axis, a 4 in [100 mm] service strip on one long side, and 6 in [150 mm] above the top of Z travel. For a 48 x 24 in router, that works out to a clear interior near 70 x 48 x 36 in [1780 x 1220 x 915 mm]. Build the shell from 18 mm [3/4 in] plywood or MDF, line it with 1 in [25 mm] acoustic foam, and seal every seam and pass-through. Builder measurements on that construction cluster at 9-10 dB of noise reduction, about half the perceived loudness. Chips are a dust-shoe problem; the box handles sound and the strays.
How big should a CNC machine enclosure be?
Plan the interior at the machine's extreme envelope plus 6 in [150 mm] per moving axis, the service strip along one long side, and 6 in [150 mm] above the top of Z travel; on a 48 x 24 in router that is a 70 x 48 x 36 in box.
The 6 in per axis splits 3 in a side and covers your hands, the dust shoe's overhang, airflow and the accessory you fit next year. The service strip rides the long side away from the hinges and carries the vacuum hose sweep and the tool setter. Height grows 6 in past the highest point of Z with the cable chain and shoe fitted.
| Allowance | Value | What it buys you |
|---|---|---|
| Each moving axis | 6 in [150 mm], 3 in per side | hands, shoe overhang, airflow, the next accessory |
| Service strip, hinge-away side | 4 in [100 mm] | hose sweep, tool setter, probe storage |
| Above top of Z travel | 6 in [150 mm] | cable chain rise with the shoe fitted |
| Outside the doors | swing past 90° | squaring, belt and bearing service |
How do you measure a CNC machine for an enclosure?
Drive every axis to its extremes and measure the whole machine with motors, cable chains and sensors in the tape; on this class of router the true envelope runs 8-16 in [200-400 mm] past the cutting area, so size to that and never to the brochure footprint.
- X: park the gantry at the far left and measure the overall span; repeat at the far right and take the union of the two.
- Y: the same pass front to back, risers and motor mounts included.
- Z: spindle at full up, then dust shoe at full down; keep the taller number.
- Accessories: measure with the probe, mist nozzle or rotary fitted if one goes on this year.
In the worked example, the 48 x 24 in cutting area grows to a 64 x 38 x 30 in envelope once chains and motors join the measurement. Miss the chain and the gantry finds a wall at full travel, or the shoe finds the ceiling at the top of a plunge. The clearance method, wall by wall, is in the CNC router enclosure clearances guide.
What do you build the walls and lining from?
Use 18 mm [3/4 in] plywood or MDF for the shell and line the inside with 1 in [25 mm] acoustic foam or a moving blanket; builder measurements on boxes built this way cluster at 9-10 dB, which your ear hears as roughly half as loud.
You need about three 4 x 8 ft [1220 x 2440 mm] sheets for the 82 ft² of surface on this box, the foam or blanket, closed-cell weatherstrip for the doors, caulk for the seams, a gasketed bulkhead plate for the hose and a lined S-bend for the vent.
The mass law of acoustics sets the shell: doubling a panel's surface mass adds about 6 dB of transmission loss, which is why 18 mm beats 9 mm and why a double-skinned door is the cheap upgrade when the reading falls short. The foam adds almost no mass; it absorbs the reverberant energy inside the box, so what escapes carries less. The two together produce the 9-10 dB, and an unlined shell gives up part of it. Blanket the doors too, because they are the weakest panels. The wall build and seal details continue in the sound isolation guide.
Where does the sound leak out of the box?
Gaps decide the result: an opening covering 1% of a wall's area caps that wall at 20 dB of transmission loss, the 10 x log10 area-ratio rule, so seal every seam and weatherstrip every door before buying a single extra sheet of foam.
This box has 11,856 in² [7.65 m²] of surface: 2 x 70 x 36 = 5,040, 2 x 48 x 36 = 3,456, and 70 x 48 = 3,360. One percent of that is 119 in², enough open area to hold the whole box to 20 dB regardless of wall build. Hold total gaps under 12 in², about 0.1%, and the cap rises to 30 dB. A single 24 x 30 in door with a 1/16 in [1.6 mm] gap all round already leaks 108 x 0.0625 = 6.75 in². Two doors, a lid seam and three hose holes spend the 12 in² budget fast.
How does dust leave the box without taking the quiet with it?
Capture chips at the shoe rather than with the walls: run a 2.5 in [65 mm] vacuum hose through a sealed bulkhead to the dust shoe, keep a 100 mm [4 in] blanked port in reserve for a collector, and let the box handle sound and strays only.
The shoe and the hose do the extraction; the small CNC dust enclosure design guide covers that end of it. Your part in the build is the pass-through: a gasketed ring plate in the wall, hose clamp on the machine side, vacuum parked outside. Once the router is enclosed, the vacuum usually becomes the louder half of the pair, so put it in another room or give it its own lined cabinet. Fit a lined S-bend vent on the wall opposite the hose; the shoe and the vent carry the heat out together, and the bend keeps the opening from working as a straight sound hole. When extraction and sound share one box, the noise-and-dust article shows the trade-offs.
What are the build steps, in order?
Work in this order: measure the extreme envelope, add the axis and service-strip allowances, cut the 18 mm shell, line it, seal it, then fit the hose bulkhead and the baffled vent last so every opening is a deliberate one.
- Drive each axis to both extremes and record the overall envelope with motors, cable chains, sensors and the dust shoe in place.
- Add 6 in [150 mm] per moving axis and above the top of Z, plus the service strip on the hinge-away side; that is your clear interior.
- Check the room with the tape still out: door swing past 90°, a walkway to three sides, a parking spot for the vacuum.
- Cut the shell from 18 mm [3/4 in] plywood or MDF and hang the doors on the service-strip side.
- Line the walls and lid with 1 in [25 mm] foam or blanket, kept above dust-shoe height and off the cutter path.
- Caulk every seam and weatherstrip the doors; hold total gap area under 12 in² on a box this size.
- Fit the 2.5 in [65 mm] hose bulkhead to the shoe and the lined S-bend vent opposite it.
- Run the checks below, then double-skin the doors if the reading is short.
What checks prove the enclosure works?
Take before-and-after readings at the same 1 m spot with the door closed: a 96 dB(A) unboxed cut should read 86-87 dB(A) after a 9-10 dB build, and that still sits above OSHA's 85 dB(A) 8-hour hearing-conservation trigger, so keep the muffs on for long runs.
- Sound: use a meter app at a fixed spot, same cut, vacuum off; 9-10 dB is the pass mark, and a vacuum-only reading shows which source is louder now.
- Heat: after a 30-minute cut, aim an IR thermometer at the router body and the walls; a wall too hot to hold a hand on for 5 s is near 60 °C (140 °F), and that box needs more vent area.
- Electronics: the stepper drivers and spindle VFD live outside the cutting box in their own enclosure, sized to hold the interior at or below 40 °C (104 °F), the ambient most drive datasheets assume; ours is rated NEMA 4X / IP66 by the manufacturer; not UL listed. The CNC control enclosure size guide walks that heat calculation.
- Dust: tape a white paper strip to the outside top seam after an hour of cutting; chips on it mean a leaking seam.
- Seals: a strip of paper closed in the door pulls with even drag all round.
Which mistakes cost you the quiet and the chips?
Four failures account for most rebuilds: sizing from the brochure footprint, skipping the lining, leaving the gaps unsealed, and housing the electronics in the cutting box; any one of them can cost half the dB or a set of drivers.
- Sizing from the cutting area: the 48 x 24 in plate is not the 64 x 38 in envelope, and the gantry meets a wall at full travel.
- Lining skipped: the bare shell gives up a good part of the 9-10 dB, starting at the doors.
- Gaps left open: the 1% cap applies at every hose hole and lid seam; foam cannot buy back an open path.
- Drivers in the cutting box: chip dust packs heatsinks and the box runs hot, while the drives want their own enclosure at or below 40 °C (104 °F).
- Lining in the cutter path: foam below shoe height loads with chips and shreds; keep it above the shoe and clear of the spindle's swing.
When is plywood the wrong answer?
Plywood suits a hobby machine in a garage; when the router cuts two shifts, lives in a washdown plant or breathes salt air, move the controls into 304 or 316L stainless built to your cutouts, delivered in 10 business days worldwide from your approval of the drawing.
A production cell also changes the chips: extraction runs continuously and the shoe becomes a ducted hood rather than a brush skirt. For the controls, the custom enclosure builder takes your width, height, depth and every cutout from one piece, and the stainless cutout page compares a new body with cutting a standard one. The decision by case: night runs in a garage, build the plywood box to these numbers; multi-shift production, steel for the electronics and engineered extraction for the chips; washdown or corrosive air, 316L with a gasket spec to match.
Catalog dimensions to compare
Compare these catalog dimensions with your component layout. Open each enclosure for its rating, material and usable space, then check those specifications against your application.
| Enclosure | Material | Outside H x W x D / display | Rating |
|---|---|---|---|
| 10 × 8 × 6 in | 304 stainless | 10 x 8 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 12 × 10 × 6 in | 304 stainless | 12 x 10 x 6 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 16 × 12 × 8 in | 304 stainless | 16 x 12 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 16 × 14 × 8 in | 304 stainless | 16 x 14 x 8 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
How many decibels does a plywood CNC enclosure cut?
Builder measurements on lined 18 mm [3/4 in] plywood boxes cluster at 9-10 dB, and 10 dB is a 90% cut in sound energy, heard as roughly half the loudness. The figure survives only while total gaps stay under about 12 in² on a 70 x 48 x 36 in box, roughly 0.1% of the surface, so weatherstrip the doors and gasket the hose pass-through before judging the result.
How much room does a 48 x 24 in CNC router need?
Measure the envelope first; on this class of machine it comes out near 64 x 38 x 30 in with chains and motors. Add 6 in [150 mm] per moving axis, 6 in above the top of Z and the service strip along one long side, which lands at a 70 x 48 x 36 in clear interior, plus door swing past 90° outside the box.
Should the shop vacuum sit inside the sound box?
Leave it outside. Once the router is enclosed, the vacuum is usually the louder half of the pair, and its motor dumps heat into a lined box with no fan. A 2.5 in [65 mm] hose through a sealed bulkhead keeps the extraction and the quiet; if the vacuum must stay in the room, give it its own lined cabinet with a baffled vent.
Where do the stepper drivers and spindle VFD go?
In their own sealed enclosure outside the cutting box, sized from their heat load so the interior stays at or below 40 °C (104 °F) ambient, the figure most drive datasheets assume. Chip dust packs heatsinks and a cutting box runs above that, so the drives get their own gasketed steel box with every cable entry sealed.
