Short answer: take both cabinets off the machine. In the worked example below, the rear drive box costs 24 in of door swing plus 12 in of depth, so removing it lets the mill sit 36 in [915 mm] closer to the wall; the side cabinet costs another 30 in [760 mm] beside the lathe. The trade is cable and structure. Keep control-to-drive runs at 25 ft [7.6 m] or less of shielded twisted pair, keep power and signal entries 4 in [100 mm] apart, and anchor anything that rolls. Size the new cabinet from heat rather than from the outlines of the parts, because that check decides where the drive lives. The decision, the numbers and the order list follow.
What you gain when the cabinets come off
Work the gain from door swing plus depth. A rear box 24 in wide and 12 in deep needs 24 in for its door and 12 in for the box itself, so the mill parks 36 in [915 mm] from the wall on its account. A side cabinet 30 in wide, 18 in deep and 44 in tall forces a 30 in [760 mm] gap to the lathe so its door can open. Take both off and the machine gains 36 in behind and 30 in on the flank. At a 5 ft machine length, the rear band alone returns about 15 sq ft to the middle of the shop.
The worked example that runs through this article: a knee mill with that 24 x 12 x 30 in rear box, a 30 x 18 x 44 in side cabinet, a 3 hp [2.2 kW] retrofit spindle drive measuring 7.1 x 5.5 x 6.7 in, and three 1 hp [0.75 kW] axis drives. Treat its weights and wattages as assumptions and replace them with your machine's figures. The new control takes roughly half the floor area of the tower it replaces, which is what makes the move practical instead of a reshuffle.
| Arrangement | Floor space it frees | What to watch |
|---|---|---|
| Cabinets stay on the machine | none | 36 in behind and 30 in beside stay consumed |
| Free-standing cabinet on casters | 36 in behind; the mill parks at the wall | Anchor when parked, bond it, leave a service loop |
| Cabinet on the wall behind or beside the mill | 36 in behind; nothing on the floor | Service access, hinge side, handle height |
| Small drive box on the ram side | 36 in behind and 30 in beside | Heat: only small loads fit a sealed box |
Where each cabinet goes
A rolling cabinet parks where you work, so give it the room a fixed cabinet would get. Where you service the gear energized, NEC 110.26(A) asks for 3 ft [900 mm] of clear depth in front for 0-150 V to ground in Condition 1, 30 in of width, and doors that open 90 degrees. You shut the mill down and lock it out between jobs, but keep the 30 in aisle anyway so panels open and hands fit.
A wall cabinet works when the wall behind the machine has room at the hinge side. Hinge the door on the end away from the machine so the swing lands in open floor. If the cabinet carries breakers, NEC 240.24(A) keeps the center of the grip of the highest handle at or below 2.0 m [6 ft 7 in] above the floor, and that sets how high the box can hang. The mounting side is covered in the enclosure mounting guide.
A ram-side box takes the smallest load and buys the most clearance. Put a drive there only if the heat check in a later section passes, because a sealed stainless box has no fan to save it. The CPU, servo drives, terminals and 24 V supply go in the main cabinet, sized next.
How far the control can sit from the drives
Distance is a noise budget, so spend it deliberately. Plan control and encoder runs at 25 ft [7.6 m] or less of shielded twisted pair. Drive manuals document encoder runs up to about 10 m [33 ft], past which they call for boosters or repeaters, so the shorter you park the cabinet, the more margin you keep. Longer is possible with the booster the manual names; shorter is cheaper than debugging.
Terminate the shield properly and the length figure holds. Clamp the shield 360 degrees to chassis at both ends, at the drive connector and at the cabinet entry plate, and add a ferrite at the drive end on the longest run. Inside the cabinet, land power and signal entries 4 in [100 mm] apart, run them in separate duct, and cross them at 90 degrees when a crossing is unavoidable. Cable selection is its own subject; the page on selecting shielded twisted-pair cable for VFD control wiring walks it.
Prove the layout before you bolt it down. Run every axis through full travel with the drives live and watch the positioning. Instability that appears only after the move is a routing and shielding problem first and a tuning problem second; the checks in twisted pair inside a metal enclosure sort out which.
Rating, material and the heat check
Match the rating to the mess, not to the machine. A dry corner with no washdown runs fine in Type 12 coated steel through the custom route. Coolant splash, chip slurry or hose-down takes Type 4X stainless. Cutting-fluid concentrate, brine or salt air moves you to 316L. Our stainless boxes are rated NEMA 4X / IP66 by the manufacturer; they are not UL listed. IP66 in IEC 60529 means dust-tight plus 100 L/min water jets from a 12.5 mm nozzle, which is hose-grade. One gland or vent with a lower IP sets the whole assembly to its rating, so size every gland to its cable and seal the unused entries.
Assume 3% of rated power as heat, the middle of the 2-4% a drive datasheet lists, and replace it with your drive's own figure. The retrofit spindle drive sheds 0.03 x 2,200 W = 66 W. Start with the small box. A 16 x 12 x 10 in 16 x 12 x 10 304 stainless wall-mount enclosure has an external area of 2 x (16 x 12 + 16 x 10 + 12 x 10) = 944 in² = 0.61 m². Stainless walls transfer heat at k = 3.7 W/m²K, so the rise is 66 / (3.7 x 0.61) = 29 K. In a 25 C shop the inside sits at 54 C, over the 40 C most drives allow unless the datasheet says more. The box passes the fit check, 9.88 in of inside depth minus the 6.7 in drive leaves 3.18 in in front of the face, and fails the heat check.
Main cabinet next. A 36 x 24 x 12 in 304 stainless wall-mount enclosure gives 2 x (36 x 24 + 36 x 12 + 24 x 12) = 3,168 in² = 2.04 m², so the same drive rises 66 / (3.7 x 2.04) = 8.7 K: inside 34 C in a 25 C shop, 39 C at 30 C. Add the rest of the load, three axis drives at 22 W each plus an assumed 20 W of supply and logic, and the total is 132 W, which lifts this cabinet 17 K, about 42 C. Over the limit again.
| Load in the retrofit cabinet | Heat | 36 x 24 x 12 in cabinet, 2.04 m² | 48 x 36 x 12 in cabinet, 3.53 m² |
|---|---|---|---|
| 3 hp spindle drive alone | 66 W | 8.7 K, inside 34 C | 5 K, inside 30 C |
| Spindle, three axes, supply and logic | 132 W | 17 K, inside 42 C | 10 K, inside 35 C |
The 48 x 36 x 12 in 304 stainless cabinet carries the full load: 132 / (3.7 x 3.53) = 10 K, inside 35 C at a 25 C ambient. Use the 36 x 24 x 12 in cabinet when the move is drive-only and the axis drives keep their machine-mounted home. The ram-side box takes one 22 W axis drive and the terminals: 22 / (3.7 x 0.61) = 10 K, inside 35 C. Sizing from scratch is in the CNC control enclosure size article and the enclosure sizing guide.
Inside, set the DIN rail and wiring duct to the layout in the backplate and DIN rail guide, and keep duct fill at or under 50%, the cap NFPA 79 sets in section 13.5.2. Leave the bending space NEC 312.6 asks for at the bigger terminals, and depth for it in front of the drive.
Anchoring, bonding and cable entries
Casters roll and lock, and that is not an anchor. A 300 lb [136 kg] cabinet 24 in deep and 44 in tall tips with 300 x 12 / 44 = 82 lb [365 N] of pull at the top edge, which is one good shove. Fit a wall bracket with a quick-release pin so a shove, a forklift or a quake finds steel instead of a rolling base; unclip it only to move the cabinet. Bond the cabinet to the machine and its conduit as NEC 250.96(A) asks, so metal parts likely to carry fault current connect together, and keep NEC 250.4(A)(5) in mind: the earth is not the fault path, the grounding conductor is. The wiring side is in the grounding and bonding guide.
Bring cables in through the bottom wall and size every gland to its cable, because the gland's seal is what holds the rating you paid for. Keep the power entries 4 in [100 mm] from the signal entries and form smooth bends at about 8x the cable OD, the static figure cable datasheets print; the plier-creased 90 degree bends in an old cabinet are where insulation fails. Leave a 12 in service loop coiled at the machine end so you can pull the mill forward to tram it without loading a connector. If the new cabinet carries the main disconnect, put the door-interlock checks from the disconnect article on the list before first power-up.
What to put on the order
Send the layout, the heat figure and the entry schedule with the order, and the cabinet arrives cut, gasketed and ready to hang. The spec table below is the worked example.
| Item | Spec | Example retrofit |
|---|---|---|
| Main cabinet | 48 x 36 x 12 in (H x W x D), 304 stainless, removable backplate, DIN rail and duct | 48 x 36 x 12 in 304 stainless enclosure, 132 W load, 10 K rise |
| Chloride or salt-air version | Same footprint in 316L | 48 x 36 x 12 in 316L stainless enclosure |
| Drive-only cabinet | 36 x 24 x 12 in, 304 stainless | 36 x 24 x 12 in 304 stainless enclosure |
| Ram-side box | 16 x 12 x 10 in, 304 stainless | 16 x 12 x 10 in 304 stainless enclosure, one 22 W axis drive |
| Entries | Bottom glands matched to cable OD, power and signal entries 4 in [100 mm] apart | 2 power, 3 signal |
| Signal budget | Shielded twisted pair, 360-degree clamps at both ends, runs of 25 ft [7.6 m] or less | CPU to drives, 18 ft |
| Anchoring | Lockable casters plus a wall bracket with quick-release pin | 300 lb cabinet, bracket at 44 in |
| Floor-standing alternative | Custom build, Type 12 or Type 4X stainless, any footprint | Drawing approval, then delivered in 10 business days |
A wall-mount footprint covers most retrofits; browse the stainless wall-mount enclosures to match your wall. If the cabinet stands on the floor instead, the custom enclosure route builds your width, height, depth and cutouts from one piece: you approve the drawing and it is delivered in 10 business days. The enclosure selector turns environment, listing and inside size into a shortlist when you would rather start from the catalog, and the machine control cabinet specification article turns this table into a quote request.
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 |
|---|---|---|---|
| 16 × 12 × 10 in | 304 stainless | 16 x 12 x 10 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 36 × 24 × 12 in | 304 stainless | 36 x 24 x 12 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 48 × 36 × 12 in | 304 stainless | 48 x 36 x 12 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
| 48 × 36 × 12 in | 316L stainless | 48 x 36 x 12 in | Rated NEMA 4X / IP66 by the manufacturer; not UL listed |
Questions
How much shop space does taking the cabinets off a CNC recover?
36 in [915 mm] behind and 30 in [760 mm] beside in the worked example, about 15 sq ft of floor on a 5 ft machine. The band shrinks to 24 in [610 mm] if you keep the rear box and remove only the side cabinet, and grows to 66 in [1.68 m] if the drive moves into the main wall cabinet too. Measure door swing plus box depth at your own hinge side before you count the gain.
How long can a control cable run to a remote drive cabinet?
Plan on 25 ft [7.6 m] of shielded twisted pair as the working maximum, with the shield clamped 360 degrees at both ends. Drive manuals document encoder runs up to about 10 m [33 ft] before boosters enter. Park the cabinet closer than that and you keep margin; past it, add the booster the drive manual names instead of stretching ordinary patch cable.
What enclosure rating does an indoor CNC control cabinet need?
Type 12 coated steel handles dust and dripping liquids in a dry corner. Coolant splash, chip slurry or hose-down takes Type 4X stainless: IP66 in IEC 60529 is dust-tight plus 100 L/min jets from a 12.5 mm nozzle. Cutting-fluid concentrate or salt air moves the job to 316L. Our stainless boxes are manufacturer-rated NEMA 4X / IP66; they are not UL listed.
How do you rate the casters for a rolling control cabinet?
Weigh the finished cabinet, wiring included, and double it. A 300 lb [136 kg] retrofit cabinet on four casters wants 150 lb each, 600 lb of capacity for a 2:1 margin; rough or oily floors argue for 3:1. Casters lock but they do not anchor, so add the wall bracket with a quick-release pin that stops the shove which tips a tall cabinet.
How high can the disconnect handle sit in the new cabinet?
The center of the grip of the highest overcurrent handle, in its highest position, stays at or below 2.0 m [6 ft 7 in] above the floor under NEC 240.24(A). A 44 in tall floor cabinet clears it easily. On a wall cabinet above a bench the rule sets the mounting height, so put the breaker row low and the display above it.
