QIDALASER K Series Laser Head Set

1. Unplug the machine. The supply is high voltage; keep it unplugged while the lid is up.
2. Measure your mirror. If it is 20mm, it moves straight across into the QIDALASER mount.
3. Measure the space under the head. The lens tube and nozzle hang below the mount; make sure they clear your clamp plate or bed at full travel.
4. Check the air hose. The 5mm connector takes standard 5 x 8mm silicone hose.
5. Look at the gantry plate. A K Series head bolts to the carriage as a unit, so compare hole spacing and belt clamp position.

The head is built from aluminium alloy with a gold anodized finish. Anodizing hardens the surface and resists wear, and the colour makes it easy to spot a loose or misaligned part through the lid window.

The lens tube holds D12, D18 or D20 lenses, all at the K40's standard 50.8mm focal length. That lets you keep your stock focus distance while moving to a larger, easier-to-replace lens.

If the beam enters the lens off-centre, it exits at a slight angle and can clip the inside of the nozzle. Clipping wastes power, heats the nozzle and leaves a lopsided cut. With a 4mm opening, careful alignment is not optional.

• Tape test: put masking tape over the nozzle tip and fire a short, low-power pulse. The mark should sit in the middle of the opening.
• Near and far: repeat with the head at the front and back of the bed, and at both sides.
• Adjust upstream: if the mark wanders, fix the mirrors, not the head.

Pair the nozzle with a steady air supply. An aquarium pump gives a gentle stream for engraving; a piston pump or regulated compressor suits cutting. Turn the flow down for fine raster work so smoke residue does not spread across the surface.

A small nozzle also keeps its tip closer to the work at focus. Watch clearance on warped sheets and anything held down with pins; a nozzle strike can knock the head out of alignment. The alignment guide walks through the full beam check.

Clean the nozzle bore when you clean the lens. Resin and soot build up inside a small opening faster than a large one, and a partly blocked nozzle both starves the air jet and gives the beam less room to pass.

The first mirror mount is worth adding if yours is stiff, cracked or stripped. On a K40, mirror one sits by the tube and takes the most heat; a worn mount there makes every later alignment harder.

• Order a lens separately if your set does not include one; check the set letter.
• Move your 20mm mirrors across, or fit a fresh set while the head is off.
• Keep the old head and lens as emergency spares.

Seat the lens curved side up, towards the mirror, and tighten its retaining ring only until the lens stops moving. Overtightening cracks zinc selenide.

After fitting, find focus with a ramp test. Tilt a scrap strip under the nozzle, fire a line, and measure to the thinnest point. Cut a focus gauge to that height; the K40 setup guide shows the method step by step.

If you run a D20 lens, keep the lens size written on a label inside the lid. The three sizes look alike out of the case, and fitting a D18 into a D20 seat leaves it loose and tilted.

• Pick QIDALASER when you want the published lens-tube and nozzle dimensions to check fit.
• Pick LSYAMQF when you want the lens bundled and a choice of CVD or PVD grade.
• Pick ZQDWMND when you only need one mount or the head alone.
• Pick a drop-in head, such as the Lightobject, when you would rather keep the stock plate.

All of these heads do the same core job. They put air on the cut, hold a better lens and give you a cleaner beam path. None of them adds tube power; if cuts have faded, clean the optics and check the tube current before blaming the head.

Whichever maker you choose, order the lens and a spare in the same size at the same time. Any K Series head needs these answers first:

• Your mirror is 20mm.
• Your gantry plate and belt clamp suit a K Series joint.
• You have a pump for the air connector.
• You have CO2-rated goggles for alignment test fires.

For the order in which K40 fixes pay back, see the upgrade list.