Cloudray CR35 40W CO2 Laser Tube

Cloudray lists 20mA as the maximum working current. For long life on a 40W-class tube, the common K40 practice is to stay at or under roughly 15mA and treat anything above as short-burst territory. With a 35W rating, that conservative ceiling makes even more sense.

• Find the panel setting that gives about 12–15mA and mark it.
• Cut with two lighter passes rather than one pass at the limit.
• If cuts need more current than before, clean and align the optics first.

The CR35 fires at a 13kV trigger voltage and runs at about 9kV. Your K40's supply handles that easily; the K40 tube and supply guide covers matching the two.

Expect the tube to feel strongest when new. Output from any glass CO2 tube fades gradually with hours, so keep a note of the current your standard test cut needs; when that number creeps up, the tube is ageing.

1. Unplug the machine and leave it for several minutes; the supply produces tens of thousands of volts.
2. Measure the compartment inside wall to inside wall, not the old tube.
3. Allow for the ends. Leave room for the high-voltage lead's bend and the water fittings at both ends.
4. Check the cradles. The mounts must sit on the glass body, clear of the end caps.

If the bay is too short, K40 owners commonly fit a small extension box over a hole in the side of the case so the tube end can poke through. That is a sheet-metal job and must keep the high-voltage end fully enclosed. The K40 dimensions page has the stock figures to work from.

• Fits as is: some K40 cases have enough spare length; measure yours.
• Needs an extension: plan the box before the tube arrives.
• Choose 700mm instead: the TEN-HIGH tube matches the stock length.

Cloudray does not include a tube holder. Reuse your existing cradles if they suit a 50mm tube, and pad the clamps so they grip the glass without squeezing it.

After mounting, expect to realign. A new tube rarely fires exactly where the old one did.

Check the lid too. On some cases the tube compartment cover sits close to the high-voltage end, and a longer tube can bring the lead nearer to the metal than before.

1. Water first. Fill the reservoir with distilled water or non-conductive coolant, connect the hoses, and run the pump until no bubbles remain in the jacket.
2. Check for leaks at both nipples with the power still off.
3. Connect the high-voltage lead to the supply's HV output using the fitted connector, keeping it away from metal.
4. Connect the low-voltage return through your milliamp meter to the supply.
5. Test fire low. A short pulse at a few milliamps onto tape at mirror one confirms output and position.

Cooling decides how long the tube lasts. A bucket and pump works for short jobs, but the water warms through a long session. Many owners aim to keep it below about 20–25°C, and a CW-3000-style chiller holds that more steadily than a bucket in a warm shop.

Never fire the tube without water flowing. A dry tube can crack within seconds. If your K40 lacks a flow switch, fit one so the supply cannot enable the laser without flow.

Cloudray anneals each tube during production to reduce stress cracking. That helps with manufacturing stress, not with cold water hitting a hot tube, so let a warm tube and cold coolant meet gradually.

The packing is foam and a carton, with an air-column anti-collision layer. Glass still breaks in transit, so unpack it on arrival, sight along the full length for cracks and photograph both ends. Cloudray also warns that CO2 tubes are consumables and lose power in long storage, so buy it close to the day it goes in.

• Note the serial and keep it with your receipt.
• Test within days, not weeks, so a fault shows up inside the window.
• Keep the box until the tube has run a few jobs.

Cloudray credits its coating and annealing with more power, longer life and fewer stress cracks; treat those as maker claims. Real tube life depends on current, cooling and hours. Glass tubes in this class are commonly quoted anywhere from about a thousand to a few thousand hours.

Keep a simple log of hours and the milliamps each job used. It helps with a claim, and it shows you how the tube is ageing. Line the options up side by side:

• Cloudray CR35: 720mm, rated 35W and peak 45W, HV connector fitted, four-month maintenance period.
• TEN-HIGH 40W: 700mm stock length, published 10–12mA working current, three-month warranty.
• XYNLHZQ 40W: 700mm x 50mm, glass-head or metal-head ends.

Pick the CR35 when your bay has the length and you want the high-voltage connector ready-made.