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Home shop lasers: use and safety

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  • Home shop lasers: use and safety

    Branching this off from the acrylic-cutting thread, I thought it'd be a good topic of it's own.

    Keeping it simple, I picked up a cheap Chinese K40 tube laser cutter, which should be here in a couple of weeks. I also picked up a 15W diode laser head and driver, for mounting on either my Shapeoko router or on one of those little eBay 3-axis "engraver mill" kits.

    Yes, I know it's all cheap crap, but I'm 100% new to lasers, and blowing $6K on a Full Specturm right out of the box seems a bit silly. If these work out even a little bit, I'll likely eventually upgrade, but this was an inexpensive way to get started. All I need to do right now is engrave wood and possibly anodized aluminum, and I'm told these will do that easily.

    Anyway, I'm told that the cover over the K40, and maybe a typical set of plastic shop goggles, are sufficient for that machine, as the acrylic stops most of the infrared beam. Do I really need to worry too much past that?

    I'm also told that the diode laser, being a visible blue beam, is a lot more dangerous, eye wise, and requires frequency-specific glasses or shielding. The Shapeoko is already getting an enclosure with a front plexiglass cover. I can get some "OD3+" tinted acrylic good for 250 to 520Nm, and the diode supposedly produces 450Nm.

    Again, if I use that shielding, and use proper "close lid THEN start laser" practices, is that sufficient? Or should I go for the "braces and belt" and have goggles/glasses as well?

    Doc's Machine. (Probably not what you expect.)

  • #2
    The different type of lasers require different glasses for protection. If an enclosure has interlocks on all openings, glasses should not be required. The one laser I worked with marked steel and would blind you instantly if exposed, but the work area was totally enclosed and if any access panel was opened the laser was disabled. We did not have any glasses or goggles available.


    • #3
      If you had any factory guarding that came with your machines in place, would you then feel comfortable working in your shop without safety glasses?


      • #4
        Originally posted by Doc Nickel View Post
        Or should I go for the "braces and belt" and have goggles/glasses as well?
        No, just avoid looking into the laser with your good eye.


        • #5
          How many eyes do you have and what is their replacement cost?


          • #6
            I would start with glasses!
            On the blue lasers, you have the advantage of being able to see it!
            I found (when fiddling with my high power laser) that the beam spreads a LOT away from the focal length. I shined it on the wall from feet away, and (after not charring anything), gave it a feel ;-)

            Once I had stable operation and had checked for blue light leakage from well away from the machine, I would transition away from glasses.

            Sent from my SAMSUNG-SM-G891A using Tapatalk


            • #7
              On a more serious note ... if you eschew the use of protective eyewear and accidentally take a shot to the eye, there is often a pretty effective treatment. The primary goal is to avoid the formation of scar tissue on the retina, and that is accomplished via steroid injections. Of course, the injections must be in the eyeball, and they will be required a couple of times per day for 7-10 days. I watched a colleague get an injection back in grad school -- it involved a doctor and 3 nurses. The doctor gave the injection while the nurses held the patient in a death grip to avoid any head movement. Good times.


              • #8
                The appropriate eye protection is very inexpensive. Get the good stuff....

                Don't risk an accidentally reflected beam. Do it!!

                1973 SB 10K .
                BenchMaster mill.


                • #9
                  The cheap little K40s are safe to run and you really dont need anything in the way of safety glasses short of genetic polycarbonate safety glasses that you would wear around the shop. The only time you will need these is when aligning the mirrors which should only need to be done once when you get it. If you have to change the tube at some point you will have to realign again.

                  The little diode lasers are very dangerous since these things are almost never put inside interlocked light proof enclosures. Technically they are illegal to import since they don't pass FDA regulations (The CDRH was absorbed into the FDA, CDRH was the organization that handled lasers and other radiation emitting devices.) In the very least you will need a pair of goggles that block out whatever wavelength that the laser operates, most of the blue ones are 405nm. You need to have a pair for every person that will be around the laser while operation, there is enough power in these diodes that even a reflection will cause eye damage. I have no idea how good the cheap glasses are that come with the lasers, I dont know if anyone has actually test these.

                  FWIW, I work with lasers for a living, any laser that has an open light path is either in soft stall or a hard stall with a laser in use sign in front of the door/curtain. We get to take yearly laser safety tests and I think I have about 4 different pairs of goggles in my toolbox to cover the wavelengths we use, 343-355nm, 514-532nm, 1047-1064nm, 9.35-9.47um and I have even used some 1550nm lasers as well. We use a different wavelength of CO2 than the standard CO2 for the processes we run.


                  • #10
                    First off, for everyone repeating, for about 287,000th time, the old "remaining eye" bit and other such nonsense, I've been looking at some of the earlier "home shop laser" threads here, and every single one has those same lines, those same gags, and the same sign slogan- often repeated several times in each thread. I don't mind humor, but geeze, get get some new material or something, wouldja!?!

                    Second, you'll note that I specifically mentioned how dangerous the diode laser is, considering its beam is not stopped as easily by common shop apparel. My question, which oddly enough was not answered by a gag sign slogan that's been around since roughly 1968, was quite simply "how dangerous".

                    Basically, if I were to fabricate a cover out of the OD 3+ tinted acrylic I mentioned, would it be safe to watch a 15W diode laser in action? Yes, I'm aware that extra glasses would be safer still. But then again, so would locking the laser in a sealed closet, bricking it over, and then operating it by satellite from a photographer's darkroom installed in the lower levels of a Hertfordshire coal mine, while wearing a blindfold.

                    I will be the only one operating it- and I don't mean that as in "I'm the only one that will be allowed to", I mean I'm a one-man band. I have no kids, no employees, and basically zero walk-in traffic. What I do have is the occasional friend who stops by to chat. If I'm running the laser- either one- and one of them shows up, walking right past the signs despite the hilarious slogans, and peers at or into the cabinet, how much danger is there?

                    Yes, I very much plan to have some quality glasses- I already have shop safety glasses scattered about, and have some rather expensive, advertised-as-tested goggles on order, along with the aforementioned tinted acrylic.

                    Doc's Machine. (Probably not what you expect.)


                    • #11
                      No, od3 is not good enough. Usually around OD4 specific to that wavelength. We use a lot from Kentek on the few machines we build that have windows.

                      But as long as you have the laser inside a box with a window of this you won't need laser glasses.

                      Simplest thing is to make a completely opaque box and put a webcam inside it to watch. Even then you want to put a neutral density filter on the camera to protect it. I fried my iPhone camera from recording high speed galvo scanning from a 5W green laser system I put together for work. Oops!


                      • #12
                        Can’t comment much on the eye safety- our lasers are commercial and interlocked.
                        We do obey ‘Rule 0’ though - Do not be on fire. We never leave the lasers running unattended, and each has a CO2 extinguisher next to them.
                        We have had minor fires when cutting, not often but it only takes 1 to ruin your day.



                        • #13
                          About 20 years ago I was in a shop with a big CO2 laser for cutting plate. Of course it fired down into the plate at very close range. Still, I was suprised there weren't any shields or warning signs. Years later I wondered how much reflection there was, etc, and if I damaged my eyes looking at it.

                          "Do not look in direction of invisible laser with remaining eye"

                          Hey, maybe that's why I can never find stuff in the shop!


                          • #14
                            With regards to how treatable a laser injury to the retina is, it really depends on the watts per square millimeter. The few laser injuries I saw were not treatable at all, because it burned the retina and killed the receptor layer. Instantly, completely and forever. They also described a popping noise which is generally thought to be localized boiling of the fluid in/on your retina.

                            Yes, I'm an eye doctor.
                            Yes, you might get lucky and just make the retina mad and inflamed, which could be treatable. Don't count on it.


                            • #15
                              Originally posted by tomato coupe View Post
                              . . .Of course, the injections must be in the eyeball. . . it involved a doctor and 3 nurses. The doctor gave the injection while the nurses held the patient in a death grip to avoid any head movement. Good times.
                              Things have improved a bit... My dad, now 94, has been getting regular injections into the eyeball for a couple of years to treat WetAMD. One doc, one eyelid spreader and according to dad, no pain.