Upgraded Laser Tube

Just finished installing and testing the new laser tube. WOW, what a difference.

I got the extension tube on Friday so I was excited to get going. The extension tube is pretty nice, better than what I was expecting.

It came with 2mm hardware but I used 3mm in place because they are slightly larger.

I cut a hole in the side of the machine, made a pattern for the screws off of the extension tube and used VHB tape as a gasket. Getting the nuts on the bolts inside the machine was a practice in patience. If I ever do another K40, I will fit this before stuffing everything inside.

The tube mounted in the original spot. I kept the distance from the first mirror the same as the OEM tube.
I opted to solder the ground and high voltage lines. The tube arrived prewired! I spliced the two high voltage lines together, soldered them and used a piece of silicone tubing as the wire cover. The silicone tubing on the splice was filled with silicone. No arcing.
You can see the flow switch in the background. I had to pull it out so I could get my giant hands inside.

Here it is all buttoned up. The hardest part was waiting for the silicone to set before I could use it. I did run the pump for a couple of hours so all the bubbles could make their way out.
You can see in the background a temp gauge on the bucket. My next project is a chiller so this is only temporary.


Looks awesome what manuf and wattage tube?

Where did you get the extension tube from?
Awesome project :+1:

It appears to be a Light Object extension.


The tube is the SPT 850mm CO2 Sealed Laser Tube (40W) from light object and the extension tube was purchased from light object as well but it was ordered through amazon.


The SPT tubes are very good. That’s what I got when I replaced my tube last year.

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So what’s the advantage of the new tube? Or did your original one fail?

His new tube is an actual 40W tube vs the 35W tube the K40s actually come with, so it’s more powerful. Power scales with tube length so the 40w tube is 130mm longer than the normal 35W tube, hence why he needed to add the extended enclosure.

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More information at

Feel free to add more information in those two topics!

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The original tube failed after less than four hours. The new tube is a true forty watt and needed the extra space provided by the extension tube. I was going to replace it with the OEM tube to avoid the extra hassle but it was not much more money. I’m glad I did, the extra power really is nice.



I’m looking at replacing my stock K40 tube which is dead now with a 50W tube from Vevor.

VEVOR Laser Tube CO2 Laser Tube 50W 800mm for Laser Engraving and Cutting Machine | VEVOR AU

I’ve noticed the Vevor 50W is about the same size as the one you purchased from lightobject. The other differences I see between the 40W and 50W are the Trigger Voltage (24KV as opposed to 20KV) and Beam Diameter (4.8mm as opposed to 2.5mm)

Were any of these things you needed to consider before using a different laser tube type?

The beam and trigger voltage were not important because i was using a different power source that was suitable for the tube. The other thing i had to do was add the extension box.