Reci vs. SPT laser tubes: Educate me please!

I see that Lightobjects sells both Reci and SPT tubes. As far as I can tell, both are considered high quality. Is the Reci higher quality to match the higher price? I’m looking at the following tubes as I work on a BOM for a DIY laser.

  • High Quality RECI W2 80-90W CO2 Sealed Laser Tube $495.00

    • Power: 80W/90W (100W peak)
    • Triggering Voltage: 24KV
    • Operating Voltage: 18KV
    • Current: 26mA (28mA max)
    • Length: 1200mm/47"
    • Diameter: 80mm/3.15"
    • Cooling: Water cool
    • Water Cooling: Water chiller is required
    • Water temperature: 20~25’C (68~77’F).
    • Warranty: 12 months
  • SPT C90 80-90W 1.25M CO2 Sealed Laser Tube $375.00

    • Power: 80/90W (105W peak)
    • Triggering Voltage: 26KV
    • Operating Voltage: 20KV
    • Current: 22mA~24mA( 28mA max)
    • Length: 1250mm (+/-10mm)/49.2 inch
    • Diameter: 80mm/ 3.15 inch
    • Water Cooling: chiller is required for cooling or warranty is voided
    • Water temperature: 20~25’C (68~77’F).
    • Warranty: 12 months

I don’t want to be “penny wise and pound foolish”. I have enough room for either tube in my design. The $120 difference isn’t trivial but if there’s benefit that I understand I can certainly swing it! I’d just like to have a clue what I’m buying; even if it’s just “tends to last longer.” I see differences in triggering voltage, operating voltage, and current. I would think that all other things being equal, higher operating current would mean higher laser efficiency, but that’s just intuition. I’d love to hear real-life experience.

And yes, in either case, I’m planning to get a refrigerated cooler: Q800 to make sure there is enough cooling capacity.

The RECI tube is considered the industry standard when it comes to glass CO2 laser tubes.

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I’m hoping we can drill deeper into what “industry standard” means here, and how it applies to a hobbyist.

Do they typically last longer? Are they more consistently high quality? Is there a difference in output? Is there any importance to the difference between trigger and operating voltages between the tubes, other than a minimum spec for required LPS to drive them? Would this power supply work for either of them since it specifies

  • Triggering Voltage: 28KV
  • Operating Voltage: 22KV
  • Current: 28mA max


This means that other manufactures compare their products to the RECI tube as to specs and productivity.

Cloudray products are good and they stand behind their sales. The PS you referenced should work well with any 80 W tube.

Looking further, I see that the 65mm T series have shorter warranty than the 80mm W series tubes. Is this due to simply having less gas in them, so that they have less margin?

Heh, looks like I’m not the only person asking questions like this.

In particular, learning that the Reci and SPT tubes are now better sealed is good news, because I expect to use this intermittently; it will be only one of many hobbies.


I keep reading… It looks like lower triggering voltage means it would be better for engraving. Cermarking hardened steel is one of my use cases (I want to mark pairs of machinists blocks) so that seems a concrete point in favor of Reci.

I’m curious about triggering voltage vs. engraving. I don’t know much about CO2 laser tubes (all my experience was with different technologies) but looking at the specifications on those, I’d be surprised if they had much performance difference.

I would select the RECI. They have a lifespan of ~ 10’000 hours and 18 month waranty, and they are constructed more robust (especially the mirror ends). We have a Reci W4 in our FabLab Lasersaur and it works fine since 5 years. The tube ends are made of stainless steel, other manufactorers use glass or brass.
Also check the CloudRay offer:

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@John_Bump I read on another forum last night folks saying that 80W is on the edge for engraving; that even there and for any higher power you needed a LPS that holds the tube at a high pre-ionization energy. However, when someone there asked how to do that there was only a theoretical answer of why it would matter, and no help on whether you could buy an LPS that had this feature… :slight_smile: And while I’ve seen used Reci LPSs for sale on Ebay, I don’t see them listed on Reci’s web site.

I care more about cutting than engraving, and I want to be able to cut ¼" plywood and MDF reliably, and to cermark/moly hardened steel as well as aluminum, so I’m going with 80W anyway, and I’m not going to stress about this.

I just figure that no matter what the slew rate when you engage the LPS, a lower triggering voltage will turn on sooner. Probably not enough to matter.

@cprezzi Working fine for 5 years in the FabLab is a good recommendation! And for where to buy them, I have both cloudray and lightobject in my BOM spreadsheet where I can change the quantity of either depending on where I want to buy it from. :slight_smile:

I was thinking of Lightobject for the laser at least for shipping from the US to the US instead of importing. I recently had a few small, cheap 3D printer parts mailed to me from China get stuck in customs for over a month, and a few years ago customs couldn’t read the label for how to open a package for inspection and it was pure luck that the small parts they left rattling around inside stayed inside the half-open bag they put the disassembled box into.

A $40 premium to avoid that seems not crazy to me.

Even if I bought everything laserish in my build from cloudray, I would easily fit in the personal use duty exemption limits, but if a customs officer is having a bad day I’m probably kind of out of luck. But I haven’t decided. And I’m almost certainly ordering at least some parts from Cloudray. They have a mirror/head set that is a good match for what I’m designing and comes with a II-VI lens and mirror set as appropriate for an 80W tube.


Shipping is more to the US from cloudray, so it’s actually only a $19 premium to ship from the US to the US, not worrying about customs, working with a company that is on a US timezone.

I’ve since realized that this could be managed in software (just use % power too low to fire the laser for off) or hardware (trim pot for the low state) and I think doesn’t have to be an LPS feature. This makes me consider a 100W instead of 80W tube.


I would go for the 100W, if your main target is cutting. For better engraving quality you can always use dithering instad of power modulation.


I did a lot of work on this early on and walked away unconvinced that the laser has anywhere near the response that folks think or need for the resolution they think they are engraving at… never found any evidence of what the real laser response time is.

My conclusion for engraving was, slow way down and get to the smallest spot size possible. Alternately just use dithering. Since that time spot size reduction and better optics has shown good results.

There are a couple of references where PPI systems have been built with quite a bit of complexity.
There is plenty of evidence that holding the tube pre-ionized can improve response time, however I have not seen any clear response results. There is also a debate as to whether driving a tube this way shortens its life.

I don’t do much engraving so I never went into more depth. Not surprising to me, I have seen lots of tweaking to get to acceptable images, then there are other users and machines that just seem to work like magic :)!


@donkjr thanks! Were the two Google+ posts you linked to at the top of your blog among the posts for which I was able to successfully save the images? I looked through your posts from before the December 21 2016 date of that blog post but it wasn’t obvious to me.

It certainly makes sense that holding the tube at a high prio-ionized state could reduce tube life, so if I ever did that, having a switch for “engraving mode” would be possible. But honestly if I see alternating offsets from engraving boustrophedonically, I’d expect (mechanical) backlash to be the primary cause.

Since cutting is my primary purpose, and I understand that there is something I can do later if I start engraving and find it to be an issue, I can stop worrying about it and take @cprezzi’s advice and move up to 100W.

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Someone must have had their coffee already this AM :slight_smile:

Mmmm I dont know where those images are. However there ARE many files out there for grey shade testing.
They may be these:

Calibration 5%.BMP (746.6 KB) Calibration 10%.BMP (98.8 KB)


Definitely the word of the day. Actually a fun word to say once your figure out the pronunciation :smiley:


Sorry, common term of art in computer science. But I do enjoy using it! :slight_smile:


That’s going to replace supercalifragilisticexpialidocious as a word with the most syllables that I can pronounce!


W4 is on order. I also ordered some less expensive optics than the II-VI set that I bought with the head, so that I can make my initial mistakes with less expensive parts, and then take better care with the good stuff. I also got every focal length that works with the tubes they sent, plus a couple that will require making or finding alternative nozzles.