Speed and Power Ponderings

I understand the concept behind adjusting speed and power to dial in appropriate manual settings, and I usually opt for the fastest cut possible, mostly because I’m impatient.

But I’ve been pondering this question: Is there a reason I should consider slowing down the machine and going with lower power? For example, if I get the same result engraving at 1000/70 as I do at 500/45, am I sacrificing a little bit of the life of the machine by opting for the faster option?

Any thoughts?

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Hmmm. I’m not sure about machine life…but sometimes speeding up doesn’t do any good, because on intricate cuts the head can’t get up to full speed anyway. Just another thing to factor in. :blush:


I think (and emphasis on the think) the laser life is what it is regardless of speed / power. You might be wearing down the components of the XY axis slower because faster speed might errode those. But perhaps not.


Good thinking.
I found this info regarding tube output:

  • A quick rule of thumb for the narrow tubes; (50mm / 2″ diameter) is 5 Watts per 100mm of tube length.
  • Fat body tubes; (80mm / 3.15″ diameter) are typically 7~8 Watts per 100mm of tube length

Our tubes on the basic (and probably the plus) are roughly 2 inch diameter and around 32 inches long (not precise but close). If the above info is correct then the tube is 40 watts as claimed. I guess some cheap lasers claim a number but overdrive a lower wattage tube which greatly impacts the life expectancy. Now, we have a power setting of 100 and another setting of full power. Most people would assume the 100 was full power so are they overdriving it to use the full power setting or what? That (using full power) might impact life expectancy but I am only guessing.
I also read, and it has been stated in here many times, the tubes have a life expectancy of around 2 years. Most tube manufacturers only claim a minimum life expectancy of 18 months but not the overall life expectancy. I haven’t heard of anyone with a glowforge needing a new tube after 2 years and most of the early machines are still humming along after 5+ years. They do slowly lose power over time and the older machines most likely require higher settings to get the same effect as the newer machines.


I’ve managed to reach EOL on one Glowforge tube so far. It didn’t quite make it to 2 years.

It was put into service in 10/2019 (my GF #3, but it was new not refurbished).

It was no longer able to consistently cut dense 1/4" materials less than two years later, in 7/2021. I replaced all of the optics with brand new parts, along with the air assist fan, to no effect.

GF customer support attempted a software fix that slowed down all cut speeds on the machine, but by 10/2021 it wasn’t able to cut those materials even at the minimum speed, at which point customer support said it was time to replace the tube – which was accomplished by replacing the whole machine.

My use case consists primarily of cutting 1/4" MDF (aka draftboard) at 132/full for several hours a day. So I’m running the tube hot and long.


Well I stand corrected, but you are the first now that I have heard of. Yeah I think running at full power is probably over driving the tube.


So the option of tube replacement for $500 is no longer available?


Nope. Only complete replacement with a refurb machine.

Which is why my machine is basically done now that my tube is failing, as I removed the exhaust fan and cut out the grate - they won’t accept it for replacement.

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I’ve noticed this, and when the head starts zipping around at a frenetic pace, it makes me feel a little irresponsible for being impatient. Kind of like the time in college when I pushed my dad’s Volkswagen bus too hard and threw a rod.


Scores I think present a good case for considering speed. For vectors, the head at full speed slams around every corner and vertice. On intricate designs, it borders on violence to the machine IMO.

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At the time in 2021, they still had that $499 price in the FAQ on the website, and honored it when I pointed that out. Since they haven’t offered repair services in a few years, they just swapped the whole machine for the $499.

In one of the website redesigns since then, they took down that FAQ, and have quoted people more recently the higher ($1200ish?) price for a replacement machine even if the laser tube appears to be the only problem. I don’t think they’re honoring that price any more.


They posted here a while back that it would no longer be offered.

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Thanks! You got lucky. :+1:

I think to myself when choosing the cutting speed “which do I want least, being annoyed waiting two hours for the engrave to finish or being annoyed for years that it could have been done better”

Engraving speed is weird anyway. There are two circumstances: one is the time (and area) to slow down stop and speed up between passes, and the other is the time actually engraving. The first will not change at a given speed but take longer as the speed increases. The second will take less time as the speed increases. So if the engrave is spending more of its time engraving than turning around (i.e. a wide engrave) then a faster speed will shorten the time. However, if the engrave is narrow then a faster speed will spend most of the time changing direction and take quite a long time.

For myself, I would much rather take the time if needed to get the best out of the machine that I can, so while some folks use a low LPI to get the job done faster, I use a high LPI to get the job done better, It is all choices.

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The 100 setting is to provide consistent comparable performance settings for all models. It’s only the Full setting that is different between GF models. It is not a % of rated power.

The Full setting is as close to 100% power as GF allows. Several years ago Dan noted that it was not in fact 100%. He said the power was managed to ensure the projected avg 2yr lifespan.

CO2 tubes have a flat lifespan curve up until somewhere in the 95-98% range. At that level the lifespan crashes precipitously. So most laser operators limit their machine from using 100% power. In fact, the control software that drive a laser can generally be set to prevent a user from actually using 100%. Any power setting over say 95% is implemented in the control circuitry to 95 (or whatever the max power setting was set to).

That is an “urban legend” supported by Dan’s statement that they expected an average lifespan of 2yrs. Some here have misconstrued that to mean they have a design life of 2yrs. They then state that as fact with posts ad nauseam but that doesn’t in truth make it a fact. It’s also belied by the fact that few tubes have been provably expired even though most have passed the 2yr milestone without incident.

A glass CO2 laser tube can last for a decade or more. We have evidence of that from an ex-GFer whose ULS tubes (she has 2 machines) are in their 2nd decade of use. And hers is commercial use so it’s not a matter of babying them. Hers is not the only example but it’s one many people here are familiar with.

Reci tubes and other high-end tubes can last longer or be recharged. Since the GF tube is a bespoke design, it’s likely it’s manufactured to a higher standard and thus likely to last longer than industry averages - probably at least as good as a Reci tube.

The custom power supply is more likely to fail (based on my EE training) than the tube. There’s a reason most lasers aren’t using custom variable power supplies to provide the juice for the laser. GF (per Dan) meters the power supply output vs cycle timing to provide the variable power output at the tube. That metering caused delays in the release of the machine and the power supply has been reported as broken far more often than tube fails. Since declining laser performance can be a symptom of declining or failed power supply output, folks reporting that their tube is dying might also really be seeing the death of their power supply.


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