FWIW I’m using the Ortur compressor and I get very little soot, mostly nice clean cuts on my LM3.
I’ve also found the material test card doesn’t match up with what I’m cutting. For example, 3mm ply material test I should be able to cut 1 pass @ 400(mm/sec)/90. But there are too many incomplete cuts when I cut a pattern. I realize the ply can vary and have harder areas, but I find the most consistent results are 300/90 1 pass, tho the material test say I should be able to go 300/60.
I’ve been doing some intricately designed ornaments, and they need to be cut through and cleanly.
I’ve tried the 2 pass method but it just doesn’t work for me time wise, I’d rather cut it once and be done.
Yeah, I also think its mistyped - that should be mm/min. I also did the cut test on 3mm ply which I do cut all the time and on the test card I got thru with even less then 400 in one pass. But that’s only for straight lines and also not always - different stock of plywood and different axis… Also am cutting ornaments with lot of details and that get not cut 400mm/min. I’m setting my cut layer now to 420mm/min and 2 passes. And here I stick - I for sure get cut thru and don’t jave to bother with that. But I also would love to do it faster - that’s why I upgraded to a new laser module.
I may be off the mark here, I’m relatively new to this game, but found a video on YouTube regarding the use of air assist, it’s a bit long, but found it very informative, blows away the theory of more air, its entitled, “RDWorks Learning Lab 223, Air Assist, why, how and when”. Well worth a look.
That is an amazing video. Awesome and a must to watch for everyone using lasers to understand what’s going on. I’m impressed. I just have to transfer all these impressions to my workplace now. I’ll have to test what I saw and learned.
My conclusion for now is that I have enough air pressure (0,03mpa = about 5psi) to get an adequate amount of a stable airflow - I think I have to turn the air flow a little bit down as it may be to high. Also an important factor is the air nozzle hole, which has to be way smaller for cutting compared to engraving. And the last, maybe the most important conclusion might be that the best cuts can only be achieved with a thru cut in one single pass - or at least getting thru the material in the first pass. There can be another pass, but it’s important, that the first cut goes thru the material, so the fumes can pass and exit under it. So high power, low speed, the right amount of air (not too much!) to drive the fumes thru the kerf under the material. And there comes in play one of the suggestions above, to differentiate the cut with two layers with different settings - so the first pass could be high power, very low speed and then the next pass on another layer with some less power and maybe a higher speed to just cleanup the cut and make it realy thru on the whole path.
In that video my problem is clearly visible - the part with too much airflow and the soot being blown on top of material which then has to be sanded → that should be too much airflow, which scatters the soot all around the workpiece. I am eagerly awaiting the first results of my tests.
I agree Dean, this video blew me away (pardon the pun), it changed everything that I had taken on board, about the subject. Think everyone should take a look, it is so comprehensive. Onwards and upwards my friend.
I watched this video and the presenter does a fine job of explaining.
My take on it is the big factor about too much pressure forcing the cloud down to the surface.
Ideally the air assist should only be used to keep the smoke away from the lens and keeping the surface clean needs to be assigned to crossflow air.
Perhaps a setup with a minimum air flow through the lens, and a tiny orifice pair mounted along the x and y axis to direct flow into the cut and also form a flow layer over the surface (cross flow).
I run my air assist from my shop compressor at about 5 PSI with a dryer and no restrictor valve. I’ll have to at least think about getting a cross flow going in addition to my cutting rooms cross ventilation (primarily used as my spray finishing room)
Biggest tip from the video is however to test, test, test!
Tweaking the air parameters looks to make a big difference, but alas it is very material/cut parameter dependent.
Yep I gave it a try. Did now lower the speed from 420 to 300mm/min, turned up the power from 90% to 95%. The test was a 10cm straight line on the Y axis. It didn’t make all the way thru. Rotated the ply (before the cutting line was with the grain, now against the grain). No noticable change.
Then I added a sublayer to the main layer - another pass with lower power, 80% and speed 500mm/min. The cut is clean, the kerf is almost equal on both sides. But now I’m getting wet sooth on the back of the material. I think that could be of too much power and the beam hits the alu mesh I’m using for the cutting bed. Also seen in the video - when the material was not lifted enough from the underlayong metal plate.
Also did almost close the valve of the airflow - can’t measure the pressure and the airflow, but it’s really low - just so it’s blowing the smoke away. Well, have to test even more - a few years of testing and I’ll hit the point
I know the feeling, test until you solve the problem, then realize you have run out of your material and need to buy more (which is no longer produced)
I always elevate my cut throughs just because of all the crud that shows up on the underside. I hope I’ll remember all these “tricks” before my mind start to go…
Yep. Ofcourse I also lifted my workpiece, but with that honeycomb I found lying around (a piece of a cooling unit) the raster is too big (window size is about 4cm x 4cm) all the small parts fall down and they then get accidentaly engraved the last thing which happened was that one of the pieces fell down and stood right up, the air nozzle cathed it and I had to replace the whole laser module a few weeks ago because of that. Now I added another mesh on top of the lifted honeycomb to ensure the small parts not falling down - now I get burns on the backside…
It’s all about improvisation. One day, when I make enough €$ with these diode toys I’ll probably get a CO2 beast with all the accessories built in and will not have to bother with all of that. Or it may also be just a dream
Sorry RobertE for my not as excellent English not being my native language, so it could be I misspelled some words here and then. Looked now back to my last post and edited it, to check for some spelling mistakes. I now will know it’s soot and not sooth
As speaking of cutting speed - I did a few tests yesterday as I described above. But I can’t get a clean cut all the way thru the 3mm on the whole path - there are some parts which are not being cut thru. Therefore I have to lower my speed or make a second pass which can be lower power and higher speed (I call it a RECUT pass). On the testcard the squares fell out even at 350 90% but can’t make use of that on real workpieces with lots of curves and also the wood changes from one to another… But am still happy to get it done much faster as opposed to my previous LU1-4 which could do the same job at only around 220mm/min and 95% at 3 passes. That still is a huge improvement.
the last thing which happened was that one of the pieces fell down and stood right up, the air nozzle cathed it and I had to replace the whole laser module a few weeks ago because of that. Now I added another mesh on top of the lifted honeycomb to ensure the small parts not falling down - now I get burns on the backside…
