It is my opinion that including the CNC and laser, the most dangerous piece of equipment that I own (As in, likely to cause me injury) is still the table saw.
That certainly does not mean that I take the laser lightly, but it puts things in perspective.
The laser is certanly capable of doing me serious injury. At full power, I’m certain that it can do considerable physical damage to flesh, not to mention the possibility of eye injury. I’m trying to get a good cover for mine, made more difficult by the pandemic. (It’s really difficult to get acrylic in anything other than transparent, and even that is hideously expensive. I wanted some red tinted in order to serve as protection, but haven’t been able to get a suitable sized sheet.
Almost any power tool can blind you in an instant. All of them can eject debris at speed, and therefore they all deserve caution and respect. Most power tools can cost you flesh and bone, too. My 5.5W laser probably won’t cause any harm that won’t heal, painful though it may be. Something in a 40W class could probably do significantly more damage, but I would be commesurately more careful with it.
I am unlikely to tell people that they’re being too cautious when it comes to preventing injury, but I do believe that these can be perfectly safe when used appropriately.
I don’t know what “suitable size” you’re looking for or what is considered “hideously expensive” to you… but I once purchased couple of 12" x 12" laser shielding panels from JTechPhotonics. I see that they also have 1/8" shielding panels up to 24" x 24" listed in their shop. Possibly they might have something suitable?
I read somewhere that table saws are something like 40% of all shop accidents. But I also use it probably 40% of the time in my shop.
It is hard to decide what is more risky, and humans are terrible at estimating very small or very large numbers. Even worse at estimating very small number times very large ones (if you have a 0.00X% of losing a finger each time you use a table saw and you use it for Y,000 hours, what are the chances you will lose a finger?).
There also always going to be people who get hurt using the safest things and safe using the most dangerous things.
It is impossible to predict exactly, but that doesn’t mean we shouldn’t try. Unfortunately, everyone kind of needs to do this on their own, and you won’t end up completely optimized.
I agree that shop safety is a personal choice, but in some cases the operator’s concern has to extend beyond themselves. For me, the issue with the laser is that it has the potential to go a long way past the work zone and possibly impact a bystander. I can decide for myself to accept risks to me. When risks extend to others, my safety sense gets ratcheted up.
Table saw, band saw, miter saw, disk/belt/spindle sander, heating torches, sewing machine, overlock/serger can all cause serious injury if you put body parts in the “danger zone,” but that danger zone is clearly delineated and unlikely to move. Portable power tools like chain saws, circular saws and angle grinders are more likely to “run away” and cause damage to the operator’s body that is outside the intended work zone. This includes kickback due to blade or chain pinch.
Flying shrapnel from shattering angle grinding disks has the capacity to travel and do damage at a distance, as does any piece grabbed and thrown by a power tool (like a table saw kickback). The laser beam will continue on for a significant distance with enough power to permanently and instantly damage eyesight. For me, this calls for more awareness of the risks “down range” so that I’m not choosing for another a risk that they are not aware of.
Thank-you for this. I’ve been needing to design a better air assist for a while now. You just saved me a few hours. Currently I’m using a small pieced of tubing bent and zip tied to the laser.
Not the best video but gives a clear view of the air-assist in action. Bandsawn ~5mm willow plank (not very well-centered) cut in one pass at 150 mm/min and 100% power… the piece fell out on its own when picked up
Sure, Klaus. The Neje A40640 is a fixed-focus laser module that is set to focus at about 22mm below the bottom of the housing. I dimensioned the air-assist nozzle to extend 15mm below the housing… therefore there is about 5-6mm between the nozzle tip and surface of the material when focused on the surface.
I had to slightly drill the hole for the lens screw and I had to scrounge around for the right sized tubing, but I got it to work. Luckily another hobby of mine is aquariums so I have a lot of different tubings on hand.
My NEJE A40640 came with a fixed focal distance of 38.2mm. Apparently the “fixed” focal distance is adjustable by rotating the lens, though I have not played with my settings. Given how warped some of the material I’ve been cutting is, 6mm would not be enough clearance.
In my reading on air assist, I don’t get a clear answer about its purpose. Some places say it keeps smoke away from the laser line and avoids smoke buildup on the lens, others claim it is to remove debris from the cut line, and sill others claim it is to put the fire out. Maybe it is all three. I read one article that advised against using the air assist nozzle like the one you are using (where the beam passes through the nozzle), but they did not explain why. I went with a 1/8" aluminum tube, and designed the holder so the height is easily adjustable depending on my need.
It has worked well, improving cut performance and reducing staining on the wood. Also I was cutting some Halloween luminaries out of heavy paper bags last week, and the air assist was blowing bits of paper around, so I turned it off. The bag promptly caught fire, so I guess it does suppress flames.
BTW: Your posts of your engraved tiles are one of the things that prompted me to buy a laser, but even though I’ve racked up a lot of hours on the laser, I have yet to do a tile…or any significant engraving. Something to look forward to.
It prints upside down, so you could just have the print stop at a lower layer height.
I personally see all 3 benefits from the air assist when I use it. Previously I was using a piece of tubing like yours. I’m working on adding a Z axis to my laser and needed a more elegant air nozzle.
Does your design hold true for the N40630 laser as well? It looks like from this NEJE video, they say stock is 20mm from housing to plate and then focus to 17mm:
Effective air-assist does indeed do all those things – it suppresses flames, helps with clearing debris from the kerf, and keeps smoke/soot from attenuating the beam while also protecting the lens. It clearly helps during most cutting operations but is often not needed/desired during engraving operations. But the key IMO is that it needs to be both effective and controllable… strong when cutting, minimal when engraving, and directed properly into the kerf regardless of the direction of travel. So, I modeled this air-assist setup similar to any number of CO2 lasers machines on the market… thinking that they would know best how to do this stuff
My setup consists of a nozzle, a ball-valve (zip-tied to back of X-carriage), and a modest compressor…
Obviously, I’m set up to manually control the air-assist with the ball-valve but you can always segment your laser job into separate cutting and engraving files… or take your chances adjusting it “on the fly” (Grbl allows easy job pause and resume…). Also, depending on the material and its thickness, I run “wide-open” air-assist when cutting thicker material and “just barely” air-assist to engrave… barely enough to keep positive pressure in the nozzle so smoke can’t enter and coat the lens.
I don’t remember if this video is one that deals with air-assist but ol’ Russ at SarbarMultimedia has many [very!] in-depth videos that deal with all things laser… use the “search” function to find videos that have anything to do with air-assist.
When I first tested my A40460 laser I measured about ~22mm from the bottom of the housing to the focus point, similar to this drawing from the Neje website…
Interestingly, these were done with a lowly Banggood/Eleksmaker 2.5W diode laser… and no air-assist was required. I hope you’ll try again. It’s not a difficult process at all and the results can be stunning. I’ll gladly help as I can…
I show my “new style” Neje 30W laser module in my post above… but it may pre-date the 406x0 numbering scheme they have now. So, I’m not sure about the N40630 module… or the difference between A40630 and N40630.
If it’s an adjustable focus module, you can probably adjust it out a few millimeters. The major difference in the two modules I have is that the 40W lens assembly is off-center from the centerline of the module and the 30W was centered.
If your 30W module looks like the one on the left, my 30W “thing” might work fine. It could be a bit “tight-fitting”, depending on your printer, but you might be able to shave/scrape/sand it to fit. The print is easily done in less than an hour…
Good to know. I’ll install a ball valve in my air assist.
Yours isn’t about 22mm as shown?
I’m not sure why 38mm popped into my head. My focus point is at 18mm from the metal housing (not the plastic shield). I’ve run several different focus tests, and they agreed on about 18mm. Given how small the kerf is on the laser, it was difficult to tell the exact focus point, but 18mm was the mid-point between the two points I could clearly see were out of focus. I ran several tests of different types since my focus appear to be different than the 22mm to the shield in their drawing, and they agree.
[Tiles] I hope you’ll try again.
Actually, I’ve not tried at all. I authored an tile engraving, put in the max feeds that Ryan had for the Rambo board for a laser, and choked on job time. I don’t feel comfortable being away from the laser, and I haven’t had the large chunks of time to be in the shop to babysit the machine for an larger engrave. But doing some tiles is definitely on my stack of things to do this Winter.
And thanks for the YouTube channel reference. I’ve had more difficulty finding good laser content on YouTube compared to the material on CNC work.
