A 40W glass tube in the K40's stock 700mm by 50mm size, sold as a 2022 new-type design with metal end fittings. zwqpeic publishes the dimensions and little else, so the checking falls to you.
zwqpeic gives you four facts: 40W, 700mm long, 50mm across, and a 2022 new-type build with a metal head. There is no rated current, no lifetime figure, no coating claim and no warranty term. Treat it as a bare replacement part, and make your own checks count.
The two dimensions are the important ones for a K40. The stock machine carries a 700mm by 50mm tube in its rear bay, so this one should seat in the existing saddles without cutting the case. Confirm that on your own machine before you order, because K40s are not all built the same.
The same 40W, 700mm, metal-head description appears on XYNLHZQ's tube word for word, which suggests both come from one factory under different names. That tells you nothing bad by itself. It does mean you should compare the two on warranty and delivery terms rather than on the glass.
| Spec | Value |
|---|---|
| Rated power | 40W |
| Tube type | Sealed CO2 glass tube |
| Wavelength | 10.6 µm (10600nm), as for all CO2 tubes |
| Length | 700mm (27.56 in) |
| Outer diameter | 50mm (1.97 in) |
| Version | 2022 new type |
| End fittings | Metal head |
| Cooling | Water-cooled jacket |
| Use | Laser engraving and cutting machines |
| Fits | 700mm tube bays such as the stock K40 |
| Power supply | 40W-class CO2 laser supply |
| In the box | 1 tube |
The metal head in the name refers to the tube's end fittings. zwqpeic publishes no drawing of them, so do not assume the hose barbs, terminal and end diameters match the tube you are pulling out. A mismatch here costs you an afternoon, not the tube, if you catch it on the bench.
Lay the new tube beside the old one on a towel and compare before anything is wired.
Nothing in the description says the leads are pre-connected, so be ready to make the high-voltage joint yourself. Wrap the lead tightly around the terminal, then insulate it with silicone sleeving or high-voltage sealant rated for the job. Standard electrical tape is not enough on a K40 anode.
Route the return lead back to the milliamp meter or supply terminal it came from, and keep it away from the high-voltage wire along its whole run. Tie both leads down so the gantry, the lid hinge and the exhaust duct cannot rub through the insulation over time.
Unplug the machine at the wall and wait before any of this. The supply can hold a charge after switch-off, and the tube and power supply guide covers the pinout and discharge steps in full.
A tube with no stated current rating needs a careful start. Fill it, bleed it and run it low before you ask for full power. Most failures on a fresh tube come from air in the jacket, a bad high-voltage joint or cooling that stops mid-job.
Work through the start-up in this order.
| Setting | Starting point for a 40W K40 tube |
|---|---|
| Everyday current | Around 15mA or lower, measured on an analog meter |
| Short bursts | Keep well clear of about 18mA |
| Coolant temperature | Cool, ideally below about 25°C |
| Flow check | Before every job, every time |
These figures are the K40 community's usual limits for 40W glass tubes, not numbers zwqpeic has published. Lean to the low end with an unrated tube. If your K40 only shows a percentage, fit a milliamp meter in the return lead before you trust any setting.
Keep a simple log for the first few weeks: date, current, coolant temperature and what you cut. If the tube starts needing more current for the same job, you will see it early, and you will have a record to show if you need to claim a replacement.
The case for zwqpeic is simple: the right size, the right power, nothing more. The case against is what is missing. Other 40W tubes that fit the K40 state their coating, beam mode, lead preparation and warranty, and a written warranty matters on a fragile glass part that travels by courier.
If you already own spare hoses, sleeving and a meter, and you are comfortable wiring high voltage, an unadorned tube can do the same job as a documented one. If this is your first tube swap, pay for the tube that tells you more, because clear instructions and a warranty save you from guessing on the one part that can bite back.
Also buy the tube when you need it. Sealed CO2 tubes lose gas slowly in storage, so a spare on the shelf is not the insurance it looks like.
Once it lases, the alignment walkthrough gets the beam centred again, and the materials guide gives sensible first settings for a 40W tube.
It is 700mm long and 50mm across, the standard K40 size. Measure your old tube and bay first, and check the metal-head end fittings clear the bay walls.
It refers to metal end fittings rather than bare glass ends. zwqpeic publishes no drawing, so compare the hose barbs and terminals with your old tube before wiring.
The two carry identical descriptions, which suggests a shared factory. Compare them on warranty, delivery and support rather than on the glass.
zwqpeic gives no rating. The K40 community's usual guide for 40W glass tubes is around 15mA or lower for everyday work, measured on an analog meter.