This is an interesting Reddit post. There are a couple of things I would like to bring up to add to the discussion.
First my credentials: I am a fellow mechanical engineer. Graduated 2014, USU. I use a fiber laser at work regularly. I dont have 20 years of experience. But im pretty sure I understand how lasers work.
Second: I thought it was interesting that “Security concerns” was the only comment that Conundrum68 has ever posted. His account is very new. Im not saying this discredits it, just gives a little bit of a troll vibe to me.
Third: The following are my responses to his concerns.
- The whole laser shooting across the room and injuring people is a long shot. But lets walk through some math and discuss why.
So the laser doesn’t come out of the laser tube ready to cut anything. That is because when cutting things with lasers, the power density is what is important. That is how much energy you are focusing into a area. A great analogy is sunlight and a magnifying glass. Sunlight doesn’t hurt, but a magnifying glass will burn. Not because the sun got stronger, but because the energy was condensed.
Now according to Wikipedia Laser cutting - Wikipedia, the laser beam comes out of the tube at about .080". Lets assume that’s what the GF does. At this diameter (and power density) the laser cant cut anything. That is why, it passes through a magnifying glass.
Now at the focal point the laser has really great power density. It was mentioned in the Tech Specs, that the GF have a .008 kerf. So Im gonna guess it has a .005 Beam diameter. With that diameter, it has about 2200000 W/in^2. To give some perspective the sun is about .08 W/in^2. So its a TON more.
Because of the magnifying glass, the light will have a conical shape to it. And when it is reflected, it will continue that shape. This means that the farther the light travels the bigger the cone will get and the lower the power density will be. But how low you ask? Will it be safe? Lets look.
Here is the spreadsheet where I tossed around some numbers.
Google Spreadsheet
I would love for someone else to look over it and see if I’m on track. I kinda did this in a hurry as im trying to go camping this weekend.
But here is the gist. IF you had the GF pro at max power and decided to etch a mirror (why? idk). Here is a list of power density with respect to distance after it bounces off the mirror.
-at focal point 2291830 W/in^2
- 2 inches away 8950 W/in^2 (a 99.6 % reduction in power density)
- 4 inches away 2238 W/in^2 (an even smaller number)
- 8 inches away 559 W/in^2 (really small)
The take away from this is that the power of the GF dies off REALLY fast.
Now it still strong? Ya, like 1000 times stronger than sunlight. But here is what put my concerns to rest. The laser is never in the same spot. It is moving around quite quickly, so even if the stars align and your object happens to reflect the light just perfectly, it is moving too fast to do any damage, it wont visit that bad spot again, and the power dissipates too quickly cut anything.
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I am no chemist and I dont know what the chemical process of the filter is. However I do feel like this point is exaggerated. He states “For example, when processing a wood product like cardboard/paper/pressboard/wood, substantial amounts of Formaldehyde and Carbon Monoxide are produced”. While true, I have stood around plenty of bonfires and never died. Remembering that your kerf is .008" when you do a project the total wood burned is probably similar to burning a matchstick or two. With no filter, it would make the room smell. And with NO ventilation, it would be a bad idea. But all of those things are easy fixes.
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The electrical worries are blown out of proportion. Yes, the glowforge has dangerous power, its a really big laser. But lethal power is also found in every house electrical socket, car battery, TV (expecially the old ones :), microwave, electric stove top and computer. I’m sure GF would do their best to mitigate risk. But this is a “toy” that should be treated with respect like any other big boy toy.
“Don’t stick a screw driver in it while its running!” - my Dad
So I hope this adds some clarity to the concerns brought up. They are concerns that should be talked about, but they are also avoidable, preventable, and difficult to produce. And I would feel confident having one in my house.