It’s no secret that my SH-G350 laser machine, a.k.a. 50W eBay laser cutter, is not really a 50W.

Yup, it’s one of the biggest scam on the eBay.  What you get is actually a machine with 35-40W watt 800mm long CO2 tube, that’s being overridden with higher current to work like 50W.

A while back I purchased a cheapest laser power meter I could find: Mahoney Co2/YAG 100W power meter probe.


Thing looks like an oven thermometer, and it actually is a thermometer of sorts. It measures by how much laser beam heats up the probe, which expands a spring inside, which moves gauge needle.  But hey, it works and works well.

Upon testing my CO2 laser tube, I noticed very strange behavior. At 100% power, I was only getting about 25 Watts of power,  but at 80% I was getting closer to 50 Watts. Also above 85% machine was making a high pitched “screaming” noises. Later I learned to associate these “screams” with sudden drop in power.

All of this was due to the fact that, I didn’t actually have a 50W CO2 tube, but rather a 35-40W one. It just couldn’t handle high current and would drop power. In the process I was also greatly shortening it’s life span.

I’ve also measured current with my multimeter and here’s what I found:

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Power setting























Normally CO2 tube in the 30-50Watt range should not be powered by anything above 20mA. So anything above 60% was overrdriving and quickly killing it.

Soon I started to experience “scream of death” at lower and lower power settings.  First it was happening at round 80%, then I could not longer cut anything above 75% and eventually even at 60% I would get intermittent power drops leaving me with half cut acrylic…

That was an excuse for me to finally get a real 60W laser tube upgrade as well as new quality Power Supply.

I ordered both (SP tube and 60 Watt PSU) from LightObject, which is a reputable laser equipment re-seller from California.

First thing that arrived with PSU. Few days later Fedex brought this really big and tall box to my doorstep.


Can you guess what was in it? 🙂


A very well packaged, both within a box…


A beautiful 60W, 1250mm long CO2 laser tube.  Some water droplets were sparkling inside. Tube was tested very recently.


It actually had labels on it, unlike the one that came with laser machine. Strangely tho none of the labels mentioned power rating…

This nice piece of paper, had very interesting information about this specific CO2 tube.


Surprisingly, it mentioned output of 60.2 Watt at 14.2 mA current. Which is great considering it’s rated for 20-22mA. Does it mean I can get 80 watts at 22mA?  I don’t know, but I might try it some day 🙂

And here’s back of the power supply. All terminals are same as my old one, some just reversed. Which means I shouldn’t have problem with connections. Physically mounting it, would be a little challenge as this one is much bigger then the one that came with SH-G350..






In the following weeks I will be slowly preparing to install new components into my machine.  There are few challenges that I need to overcome, such as building extension enclosure for a much longer CO2 tube (which will be protruding from side of the machine), getting all wiring done, and mounting tube inside.

I don’t want to just re-use ghetto mounts supplied with machine (which are basically pieces of thick rubber pushed onto tube with some metal bends and bent machine screws).  I was told about this awesome tube hangers, which I modified today to fit my 55mm thick CO2 tube, and already started to 3D print the parts.

Another upgrade will be an analog Ammeter to monitor laser tube current.



I will keep you posted on my progress!