CNC splash guard enclosure dimensions and clearances

Short answer: size the splash guard to the machine's swept envelope. That is table length plus full travel plus 4 in [100 mm] on each axis. Drop the pan floor 2 in [50 mm] below the lowest point coolant can splash.

On a bench mill with a 27 x 7 in table, 16 in of X travel and 6 in of Y travel, that works out to a 47 x 17 in interior. Add 22 in [559 mm] of clear height above the table and a 5 in deep pan. Then seal it: every cable through a gasketed gland, the coolant line through a bulkhead fitting, the sliding panels on a sealed lap.

Flood coolant over an open pan is a wet floor and a mist problem; the steps below keep both inside. Unsure between mist, flood and air blast? The mist, flood or air blast chip removal comparison shows what each method demands of a guard.

What you need

Gather these before you cut a sheet:

• Travels on X and Y and the spindle nose height at full retract, from your manual or a measured full-stroke run.
• Table length and width with your vise mounted, since fixture overhang changes the swept envelope.
• The lowest splash point. On most mills it is the underside edge of the table, where coolant drips as the table moves.
• 1/4 in [6 mm] clear polycarbonate for walls and windows.
• 40 mil [1 mm] PVC shower-pan liner for the pan floor, with solvent cement for the seams.
• EPDM gasket stock for the door lap; typical O-ring handbook values run EPDM from -50 to 150 C, which covers hot water-based soluble oil, and nitrile from -30 to 120 C for straight cutting oil.
• Gasketed cable glands matched to each cable's outside diameter, plus a 1 in [25 mm] bulkhead fitting for the pan drain.

Set the interior dimensions, step by step

1. Measure the swept length on each axis. For a moving-table mill, swept X is table length plus X travel, and swept Y is table width plus Y travel.
2. Add 4 in [100 mm] to each swept dimension, split evenly at each end. The margin covers chip throw, coolant bouncing off the workpiece, and a hand reaching in with a wrench.
3. Set the clear height above the table: spindle nose at full retract, plus your longest tool stickout, plus the same per-axis margin of headroom for the drawbar knob and spray off the tool tip.
4. Drop the pan floor 2 in [50 mm] below the lowest splash line, so the first heavy cut throws spray onto the liner instead of over the rim.
5. Slope the pan floor to a drain and line it. The pan section below sets the fall, the fitting and the liner.
6. Split the front wall into two sliding panels on an overhead track, lapped 1 in [25 mm] where they meet, with the opening sized so your tallest fixture clears it by the end margin.

Sizing a guard for a 27 x 7 in table with 16 x 6 in of travel

The inputs, measured on a bench mill run with flood coolant:

• Table 27 in long by 7 in wide, vise mounted (tape measure).
• Travels of 16 in on X and 6 in on Y (machine manual).
• Spindle nose 16 in above the table at full retract, longest tool sticking out 2 in (measured).
• Splash line 2.5 in [64 mm] below the table top, at the table's underside edge (observed drip point).
• Flood sump 10 US gal (pump tank label).

Three rules turn those into dimensions: interior equals swept length plus the per-axis margin; the pan floor sits at least the splash margin below the splash line; the pan holds a full sump dump with freeboard. The arithmetic:

• Swept X: 27 + 16 = 43 in, so interior X = 43 + 4 = 47 in [1,194 mm].
• Swept Y: 7 + 6 = 13 in, so interior Y = 13 + 4 = 17 in [432 mm].
• Clear height: 16 + 2 + 4 = 22 in [559 mm] above the table.
• Pan floor: 2.5 + 2 = 4.5 in below the table top, built at 5 in [127 mm] for a clean sheet and spare depth.
• Pan floor area: 47 x 17 = 799 in².
• Capacity at the rim: 799 x 5 = 3,995 in³, and 3,995 / 231 in³ per US gal = 17.2 gal.
• Dump check: a full 10 gal sump is 10 x 231 = 2,310 in³, which stands 2,310 / 799 = 2.9 in deep, leaving 5 - 2.9 = 2.1 in of freeboard.

The decision: build the guard 47 x 17 in with 22 in of clear height and a 5 in pan. That rim holds about 17 gal, so a full sump dumping at once still leaves 2.1 in of freeboard. The threshold: a dump bigger than about 17 gal overtops a 5 in rim, and each extra inch of depth adds roughly 3.5 gal on this footprint, so a larger sump means a 6 in pan or an overflow line down to the tank.

Pan slope, drain and chips

Unplug the machine, then give the pan floor a fall of 1/8 in per foot [1 %] down to a 1 in [25 mm] bulkhead fitting in the low corner. Run the drain line downhill to the tank with no dips, because a sagging line collects chips and sludge until it blocks. Screen the fitting mouth with a strainer basket so chips flush to the tank instead of the pump.

Lay the PVC liner over the sloped base and solvent-weld the seams into one sheet, then clamp the liner between the bulkhead's two gaskets, one above and one below. Where the pan meets the stand or a drawer slides through it, the sealing details are the ones in the coolant containment at enclosure gaps article. Plan a pull-out chip drawer or a wide mouth at the low end, because chips packed under the mill are the one thing you cannot reach around a finished guard.

Seal every entry so mist stays in

Every cable passes through a gasketed gland sized to its outside diameter, so the elastomer seals and the clamp nut only grips. Coolant and air lines pass through bulkhead fittings with an O-ring on each side. A viewing window takes a gasket on both faces; the camera enclosure window and gasket picks article shows which profiles survive coolant splash. On sliding doors, the 1 in [25 mm] lap plus a flexible lip strip does the sealing, since a sliding panel cannot carry a perimeter gasket.

Keep the electrics in their own gasketed stainless box beside the guard; ours are rated NEMA 4X / IP66 by the manufacturer, not UL listed. The 3D enclosure builder adds the gland and window cutouts before you order. If you drill that wall yourself, the field-drilled conduit entries that keep a NEMA 4X rating article gives the sealing sequence.

A filter fan is the wrong climate control in mist, because the filter loads with wet chips and the mist path rides straight through. Keep the sealed stainless box closed and let conduction carry the electronics heat instead; the passive approach for washdown cabinets is the same one behind our 316L stainless enclosures.

Capture what escapes at the source: the coolant mist collector selection and installation guide covers sizing a collector to the machine. There is a health number behind the sealing work: OSHA evaluates metalworking-fluid exposure with standard total dust sampling techniques compared against its permissible exposure limits. And when the guard itself should be a rated stainless housing rather than a splash shield, the custom stainless enclosures page covers grades and sizes; it is built to your drawing and delivered in 10 business days from your approval.

Checks before the first flood run

• End clearance. Cycle both axes to each end at rapid feed and measure table edge to wall: it should read the per-axis end margin at both ends of each axis.
• Roof clearance. Longest tool in, spindle at full retract: tool tip to the top panel reads the headroom margin.
• Water before coolant. Run plain water at full flood for 5 minutes, then inspect the floor and the outside of every panel.
• Seam hunt. Brush soapy water along the outside of each seam while mist is in the air; bubbles mark the leak.
• Drain. A minute after the pump stops, water stands only at the fitting mouth; a pool deeper than 1/4 in [6 mm] means a chip dam is holding it.

Mistakes that flood the floor

• Sizing to the table footprint. At the far end of X travel the table hangs past the wall line; the swept envelope, not the footprint, sets the walls.
• Rim level with the splash line. Spray crests on the first roughing cut, so keep the rim below the splash line by the splash margin from step 4.
• A flat pan with a corner drain. Chips pack against the far wall and the drain backs up; give the floor the fall from the pan section.
• Cables through plain drilled holes. Mist exits at each hole and condenses on the electrics box, so every penetration gets a gland.
• A pan-only build for misty cutting. A pan under an open frame is the splash-guard cousin of a dust foot; the dust foot vs full enclosure comparison weighs that trade, and the same swept-envelope math with heat and dust added is in the hobby CNC router enclosure guide.

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.

Questions