Has anyone attempted to upgrade their k40 to an 80w tube?

I’m considering an upgrade/rebuild for my first machine, which the tube has died on. I wanna go with a “real” 80w (whatever that tube length is) and get a power supply to match. Has anyone tried this yet, and if so, could you send suggestions on tube sources, power supply sources and any info of how to properly connect everything to the control board? Also, will I need to consider/prepare for other upgrade requirements to go along with that much of a power jump? Also considering getting an amp meter(?) for analog management of the power (both machines I have use a digital power control. I’ve gotten pretty used to the concept of using percentages, since that’s where I started when it comes to using laser cutters at my local Makerspace for the last few years… I’m not against making the switch from digital to analog so much as wondering how much of a learning curve there will be and wanting to take precautions to not exceed safe outputs unintentionally and destroy something. I’d be very frustrated if I got everything all set up and basically blew up the whole machine on my first run with the new setup… Thanks in advance.

An 80W tube was going to be a tight fit for my 1.5 meter wide monocle before I decided to change to 100W tube that will require an extension box. You would have a very long extension. Max power is a function primarily of length. 80W is about 1250mm (about 50 inches) long. Start from the business end of your current tube and measure 1250mm and then add the distance between your current tube and the end of your current enclosure and you’ll see how far out it has to stick.

You don’t have to give up your digital display to add an analog ammeter; it’s not a switch from digital to analog, it’s a measurement tool to protect your investment. Not spending $10 to protect a $400-$600 tube would be penny wise and pound foolish.

You’ll need a new LPS. You might consider this power supply (thanks @cprezzi):


True that, but some take out the digital panel to make space for the meter.


Will the high voltage cables be able to handle the upgraded tube, or should I replace those as well?

The wires in your K40 are unlikely to be long enough to reach the much longer tube! And if you don’t know the dielectric strength, it might make sense to buy something specified to have a strong enough dielectric breakdown voltage. It’s not expensive. By way of example, here’s 10 meters of 40KV cable for $15:

It doesn’t need to be thick wire (it’s not much current) but it does need to have electrically strong insulation.


How do I figure out what I need so I don’t invest in something not durable enough for the job? Since you are only using the supplied link as an example, I’m lead to believe it may or may not be adequate for the job. What would be the best way to find out?

I found that link easily because it’s what I bought for monocle so it was in my purchase history. I haven’t bought the tube yet for monocle so it’s in a coil. I have no reason to think it won’t work. Cloudray sells 5 meters of their variant for $6 (plus shipping from China, of course):

I don’t expect faulty HV cable to be the primary problem with stuffing an 80W tube in a K40. I expect supporting the tube to be the most interesting challenge. How big is the extension hole? That will tell you what diameter tube you could use; I don’t know whether the 80mm wide tube I linked to as an example for the expected length would fit. But what supports will you use? I’m guessing that cantilevering a 1250mm tube off only the supports inside the K40 case would be not the best idea, either for the longevity of the tube, or for the integrity of the beam; glass is flexible, and I don’t know at what load characteristics you risk decoherence. All examples I see try to support the tube at roughly equal intervals.

The RECI T1 (75W) and T2 (90W) tubes are 65mm wide and 1110 and 1250 mm long, respectively:

There are more things to think about. When you go to 80W, you almost certainly want to upgrade your optics if you haven’t already. I’m using II-VI optics.

I personally would not hang an 80W laser off a K40, and indeed even before deciding to move from 80W up to 100W was not planning to stuff it partway into a K40 case. While it’s certainly your choice how to invest, if it were my own device, my own calculus would be that it’s proverbially hard to make a silk purse from a sow’s ear. (Not trying to say a K40 is a sow’s ear, but it wasn’t optimized for an 80W laser and you have lots of engineering decisions to reconsider.)

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I would just go with cloudray wire and connectors to be sure of the quality.
You could also contact cloudray or whomever you are getting the LPS from and ask about the application and get recommendations.


I don’t see any reason that a K40 cannot be upgraded to 80W, I have witnessed it being done. That is if you are ok with a big dongle hanging out the side :slight_smile: If the optics are that bad you will find out quickly and they probably needed changing anyway.

You could think about putting an extended sheet metal cabinet that accommodates the laser’s additional length and the larger LPS. This bay could match the profile of the machine. You would end up with a machine that is as wide as a normal 80w would be.

At the same time you could extend the gantry and move all the electronics to the new extension.

I’ve thought about this many times is it better to extend or just build an entirely new one.