K40 replacement tube

Hi all

K40 Tube froze and broke, live and learn i guess.

So i have a few querys. It looks easy enough to replace and i can see prices from around £50 + Postage on AliExpress.

What is the highest wattage tube i can use without changing the LPS?
Is it worth getting any particular brand of replacement ?
Should i buy from a UK supplier to emsure better quality/support ?

I dont use the laser heavily and i am experimenting with various materials at the moment so have nothing specific in mind ( Ply and Acrylic so far).

I have a 1500x1500 “Ultimate Bee” CNC from BulkMan3D and was also looking at Gantry mounting if anyone has advice (For/Against) or links to similar projects ?


The Getting Started with CO2 Lasers category has some posts that might help, especially Where can I find K40 replacement parts?

In general, CO2 power is a function of tube length, and to increase power you may need an extension to hold the tube, depending on the original tube power.

There are brands that are better than others. Reci and SPT ara generally considered high quality. You can search here for people’s experiences with them.

the stock tube in the K40 is more like a 30W or 35W tube which is one of the reasons why you need to have a current meter(mA) on it and limit the current to make the tube last longer. But when it’s replaced with a new 40W tube the LPS can still handle the output and you can drive it at full power because good tubes are tested for continued operation at full power. So it’s worth it to get a good grade tube.

Sorry for the delay. Thanks for the info you’ve given.

How delicate an operation to refit the tubing to the tube. It seems that both of the necks were where they broke so i am thinking they must be delicate to start with ?
Any existing posts on the recommended process please ?


The glass is pretty thick but no match for freezing water which literally can crubble mountains. Fitting flexible silicone tubing to them is not difficult be I would not use a hammer. I don’t know of any specific instructions but it’s generally, remove old tube, install new tube( replace calms if installing tube of different diameter), align mirrors.

Install new tube with water ports facing up, so that coolant fills the tube with no trapped air bubbles.

Is it advisable to use some sort of lubricant to help them go over the connectors more easily?

The glass is not that fragile but take care not to apply side torque to the stem.
I have never had trouble with pushing silicone tubing onto the water stems.

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Others have use fish tank heaters and other means to keep the cooling water in CO2 laser tubes from freezing and breaking the glass.

I bought direct from Vevor.