It’s the OSHW lasersaur 80W max power. But that shouldn’t matter. The question was whether we can reasonably expect any power attenuation over ~500-600 mm of travel through the cabinet independent of mirror alignment.
It does matter 100% what brand you are talking about.
Some home made toy that was built under zero standards by who? Vs. I factory built unit that is going through full R&D and testing.
You make it sound like all tools are the same, just because they might have one same word used to describe them (Laser). When in fact you know from the start the GF is starting with a WAY better tube. And I am willing to bet, all the components are better.
And that Coletech tube… OMG!!! LOL! Any wonder you have issues with it.
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Cobbler, stick to thy last.
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@fablab_elpaso If that is your attempt at humor, I suggest you quit while you’re ahead. Not only is that off topic, but WAY out of line!
I see a post getting removed shortly… Good job!
Very curious results.
On your Near and Far test… I assume power applied for the same duration in each case?
That much of a difference in a laser at such a small distance is quite strange to me. I lack heavy experience with actual in practice lasers, and physics is ALL about ignoring as many real life issues as possible. But that is primarily because real life tends to fall pretty close to what we predict after ignoring all those messy bits.
This however, is well outside of expectations.
Keep in mind what it is… It’s a Hack-O-Parts without any standards that anyone can build in any shop. Not like the GF in any way.
http://www.lasersaur.com/
Kind of like a “kit car” Sure, They can look cool, but never quite look/work as advertised.
Hi Spike, quick primer on the scientific method:
JT had a hypothesis (that’s a fancy word for educated guess) that the power attenuation often encountered in laser cutters is due to mirror misalignment. That sounds reasonable. But we don’t accept reasonable assumptions. So we came up with a couple of tests. The hypothesis has to be testable, in the sense that it makes predictions that can be verified. Our tests were designed to eliminate as many confounding variables as possible, so we pared it down to one uncontrolled parameter: distance. Things like the brand on the front of the machine are irrelevant for these purposes. The system is as simple as possible, a commercial grade laser shooting at a mirror and bouncing into a target.
Good scientists design an experiment to try to disprove their hypothesis (that’s right we try to prove ourselves wrong…crazy right?), document the testing process and results and then show their work! That last bit is important, so that others can critique our method and/or replicate the results.
Our simplified system generated results that might seem unexpected based on what we know about how the laser should behave. If misalignment were causing the power attenuation then the spots should be the same at the near and far ends of the bed. That’s not what happened! Now we have a fun problem. We can now come up with new hypotheses about why the results are not what we’d expect. Then we can come up with new predictions, new tests and get new data…then share those results too!
You think that the brand of the machine will explain the most variation in our test system. I’d say that’s unlikely but encourage you to think about some predictions your hypothesis would make, come up with an experiment to test those predictions and share your process and results.
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Yup exact same parameters! Crazy right? And I’ve aligned and run roughly similar tests on Epilog, Universal, Full Spectrum and Trotech machines with roughly similar results. Again, things like mirror wear could explain some attenuation, but under the first pic’s test conditions we’re only bouncing off mirror #1, which is in an enclosed compartment so doesn’t get dirty or cleaned. It’s pretty much as spotless as the day it was installed.
Thanks for mentioning the Lasersaur project. It’s actually a highly capable machine, built with industrial grade bones, research grade optics and very well designed driver board. The software is under active development and the most user friendly I’ve ever encountered. It easily outperforms the commercial laser cutter that it replaced in our shop. I encourage you guys to check out the project, support the developers and build your own!
It’s amazing what you can build with a “Hack-O-Parts”. You’re right, they don’t always perform as expected…they often perform better! Check out this open source two-photon microscope built with off-the-shelf optical components that outperforms the three leading commercial systems tested! OSHW FTW.
Without word from @dan, and w/out an actual GF, this is mostly just speculation. The Tech Specs page, while not overly informative, mentions “continuous auto focus.” So, I would take any hypothesis, and comparison to other products, with a grain of salt.
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Just so you know. I am sure many people are gaining a lot of ‘directions’ to learn from. Hell, I’m catching up a lot from this convo here. I was worried about wear and tear issues maintenance issues and this topic opened them up without me asking in a separate thread 
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Question @fablab_elpaso , in the image showing the 2 paper cut. i can’t fully understand what I am looking at in the pic. care to explain a bit further?
This is a problem that plagues flying optics laser cutters in general. No one seems to be sure why. The most reasonable explanation is mirror misalignment (which the GF should take care of nicely) but these tests show that the problem persists to some degree even after eliminating mirror alignment as a factor. Focus, whether automatic or not, would not affect these results in any way. The first test is of the unfocused beam. The second is at the exact same focus (it’s a flat piece of paper). Maybe some other feature of the GF will mitigate this issue: better mirrors, shorter beam path, their spiffy TEM00 laser (vs TEM01 in most other hobby cutters, including the one used for these tests). If they really aren’t seeing any attenuation from left to right side of the bed then that is pretty awesome!
Really wishing I wasn’t out for a conference right now. I want to do similar tests on my own rig (loosely based on the Lasersaur, but we brought our cost down to about $2,000. At the expense of bed size being 900x585, a 60W tube, and no enclosure or ventilation).
Could you run a few modifications of the paper burn test?
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Find setting that barely penetrates (not just mark) paper at near range. Compare against far range
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Find settings for both previous tests (yours and mine) with initial calibration done on the far end, and then back compare to near end (granted, no idea what I am expecting to see here. Though the reverse of your test resulting in a solid black far mark and a penetration near mark would be nice, as it gives a vague sense - combined with the test I propose above) of the total power loss)
Actually, thinking about this further, just finding the power at which you make a similar mark at the far end already tells you power loss. Seeing as you know what power setting was needed in each case.
@fablab_elpaso
Ya know, adding a meme only waters down your statement and proves that you hacked it from someone else.
As far as your laser. The so called " highly capable machine" with such good parts as you say… I find it ironic that
1- They spec a Reci S4 tube
2- You are having issues with it
The common factor of all the lasers you are having problems with seems to not be the lasers.
BTW, going back and editing your posts to some how make them look like you did not say anything bad does not change the fact that it still happened. We keep full records of such things, and it’s way out of line!
fablab_elpaso
January 7
I was in the market for some gaudy pots the other day and thought about
buying it from some company called Exotic Vessels. Decided to go with
the garden department at Wal-Mart. Who knows what crazy people they
have making pots at EV under zero standards! I prefer my pots fresh off
the production line with quality assurances from the Chinese factory.
I’d advise everyone to stay away from those Exotic Vessels guys,
obviously pushing cheap home made toys.
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Really don’t like feeding trolls, but let’s try this just for fun:
I was in the market for a laser cutter the other day and thought about
building it from some project called Lasersaur. Decided to go with
the Glowforge. Who knows what crazy people they
have designing lasers at Lasersaur under zero standards! I prefer my lasers fresh off
the production line with quality assurances from the Chinese factory.
I’d advise everyone to stay away from those Lasersaur guys,
obviously pushing cheap home made toys.
Sounds a lot like you, don’t you think? Guessing you still don’t get it. I voluntarily took the post down because nobody actually wants to hurt your reputation and livelihood as an artisan. We actively support local artisans. Just thought that maybe seeing those exact same things being said about your work would lead to some self reflection and encourage you to take down your unprovoked posts bashing complete strangers’ work (whose fields you obviously don’t understand or have any experience with). Or at the very least stop making completely unqualified statements. No luck there.
I find it ironic that you don’t understand that
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In an open source design you don’t have to follow spec and you have no idea what tube we’re using.
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We’re not having problems with our laser, tube or otherwise.
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The Glowforge being amazing (which it definitely is) doesn’t require all other laser cutters to be terrible. Everything isn’t zero sum.
Zapatero a sus zapatos!
Correct, you wrote that, so it still sounds out of line no matter how you change it. But as long as it’s not directed at me or my company, go for it. I will let the GF team deal with with your out of line remarks.
As for #1 Do tell us what tube you are using? I am sure people would love to here the expert advice you have to offer. But I do have to ask, biased on your test. Did you by chance damage your tube mirrors trying to clean them?
As for #2 Really? So your whole point about showing how the output changes on your laser is just a big lie?
Please use English, it’s the standard of this forum. It is kind of pointless to make everyone have to go look up your silly joke.
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No enclosure?!?! Hardcore. 
Sorry, should’ve labeled the second pic so it’s more apparent, but that test is exactly what you describe. Settings that barely penetrate the paper at near range (circle on the bottom). Far range is the circle on the right that didn’t pass all the way through.
You guys! What is up? Dontcha hate how the semi-anonymous internet makes it easier to be a jerk without even trying? I have been the lucky recipient of much wisdom from other posts by the both of you; thanks for contributing to this forum. But can I suggest we take a break from this sword fight for some much needed entertainment?
https://video.yahoo.com/samurai-hotel-000000837.html
I’m glad Glowforge has brought us together here; let’s enjoy the opportunity to learn what we can from each other.
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Unfortunately the video is not available in my region