An aluminum air-assist head for the K40 that takes a 12mm or 18mm lens at 50.8mm focal length, or a 16mm lens at 25.4mm. It bolts on in place of the stock nozzle-less head and gives an air pump somewhere to blow.
Not every K40 is built the same, and the head is where that shows. Cloudray says this head fits when the fixed bracket on the moving axis is an M22 or M23 type, and warns that K40 brackets and setups vary. Check yours before you order, not after the head arrives.
Open the lid with the machine unplugged and look at how the stock head attaches to the carriage. Compare the bolt pattern, the plate thickness and the spacing to the head's dimension drawing. If the screw holes and air nipple do not line up exactly when you offer it up, Cloudray suggests aligning them and screwing it down; small offsets are normal on K40s.
Measure these on your machine:
The air cone adds length below the lens, so the nozzle sits lower than the stock head's opening. On a K40 with a tall bed or a raised clamp, check that the nozzle clears your thickest stock. The K40 dimensions guide lists the cabinet and bed measurements.
The mirror mount on top takes a standard 20mm mirror, the same size as the K40's stock mirrors, so your existing third mirror can move across.
| Spec | Value |
|---|---|
| Type | K40 laser head with air assist |
| Maker | Cloudray |
| Model | K40 |
| Material | Aluminum |
| Weight | 60 g |
| Lens option 1 | D12mm FL50.8mm (with spacer ring) |
| Lens option 2 | D18mm FL50.8mm (ring removed) |
| Lens option 3 | D16mm FL25.4mm |
| Unsupported lens | 20mm diameter focus lens |
| Mirror mount | Takes a 20mm reflective mirror |
| Air connector | 5.3mm outside diameter |
| Suggested hose | 5x8mm silicone (5mm bore, 8mm outside) |
| Fits | K40 machines whose moving-axis fixed bracket is M22 or M23 |
| Installation | Plug and play when the bracket matches; align screw holes if needed |
| Versions | Head only, or head with CO2 lens and mirror bundle |
This head takes three lens sizes, and only three. Cloudray is clear that a 20mm focus lens will not fit. That rules out a common upgrade lens, so check the diameter of any lens you already own.
| Lens | How it seats | Best for |
|---|---|---|
| 12mm, FL 50.8mm | With the spacer ring | The stock K40 lens size; general cutting and engraving |
| 18mm, FL 50.8mm | Ring removed | A larger, easier-to-centre lens at the same focus |
| 16mm, FL 25.4mm | Its own seat | Fine engraving detail on flat work |
Most K40s ship with a 12mm lens, and it drops straight in with the ring. An 18mm lens gives the beam more margin before it clips the edge of the optic, which forgives a slightly off-centre beam.
The 16mm, 25.4mm focal-length lens is a different tool. A shorter focal length makes a smaller spot, which sharpens fine engraving. It also shortens the depth of focus, so the beam spreads faster above and below the focal point. Use it for detailed engraves on flat stock, and go back to the 50.8mm lens for cutting thicker sheet.
Keep the spacer ring when you remove it. It is small, easy to lose in the bay, and the only way back to a 12mm lens if an 18mm one cracks mid-project.
The Cloudray 20mm ZnSe lens is one that does not fit this head; order a 12mm or 18mm lens instead.
A new head changes where the beam meets the lens, even if only slightly. Plan the swap as a head change plus an alignment check, and the first cut after it will look like it should. Skip the check, and a clipped beam will cost you power on every job.
Expect the alignment to take longer than the swap. Work one mirror at a time, mark each test pulse with the corner it came from, and stop adjusting once all four marks sit on top of each other.
Pair the head with a pump: the Cloudray 135W air compressor takes the same 5x8mm hose. Full mirror procedures are in the K40 alignment guide.
Cloudray offers this head two ways: the head on its own, or the head bundled with a CO2 focus lens and mirror. Let the state of the optics already in your machine decide.
Pick the head only if:
Pick the bundle if:
Keep it clean and it will keep cutting. Wipe the lens with lens tissue and optics-grade alcohol when you see smoke film, and check the nozzle tip for resin, which narrows the air jet. Clean the lens often if you cut plywood; the smoke from glue layers coats optics fast.
Check the lens seat when you clean. A lens that sits crooked on a burr or a bit of grit focuses off-axis, and the cut comes out bevelled on one side. Tighten the retaining ring snug, not hard.
How it compares with other K40 heads:
Air assist ranks near the head of the K40 upgrade order, ahead of bigger tubes and new boards.
Cloudray says it fits K40s whose moving-axis fixed bracket is M22 or M23, and that K40 brackets vary. Compare your carriage plate with the head's dimension drawing first.
No. It takes a 12mm or 18mm lens at 50.8mm focal length, or a 16mm lens at 25.4mm. The mirror mount does take a 20mm mirror.
The air connector is 5.3mm outside diameter, and Cloudray suggests 5x8mm silicone tube.
Yes. Check the beam is centred at the head's entry at all four corners, then find focus again with a ramp test measured from the nozzle.
Fine engraving. The shorter focal length gives a smaller spot but a shallower depth of focus, so use a 50.8mm lens for cutting thicker sheet.
