Hi there! I’ve been having an issue with my aufero laser 2 20w diode laser with the long throw laser module and Ortur rotary. Seems like it removes the coating well with the settings I have but I seem to have these lines in the stainless after I wipe everything off. Do I have my settings wrong?
I’ve etched a couple of dozen powder coated stainless steel tumblers recently and found that when it comes to laser power, less is more. I’ve done various brands all with excellent results, mostly quality brands with thicker powder coat; I think I caught a glimpse of ThermoFlask logo in one of your photos, I’ve done 8 or 10 of those very successfully. I’ve not done white though, that could possibly require a few percent more power due to reflectivity. Anyway, back to less is more, I posted my process and settings here. Yeti tumbler etching - #6 by bLouChip
Since that posting, I’ve changed from my second pass from being OffsetFill to using a 90 deg Fill scan, basically I have one layer that does CrossHatch Fill pattern, and I add a sublayer to do a Line outline of the shapes after the crosshatch fill. The crosshatch fill is at fine/sharp focus and interval of 67% of my beam width, so 0.09mm interval (I’ve more accurately measured my beam width at 0.13mm since the ref post also). I have a similar dual diode 15W +/-5 as you do.
Finally, another process change comes to mind since the ref post, Dawn liquid soap and water with an Eraser pad brief scrub is a good clean up process, seems to be as good or better than LA’s Amazing stuff.
Less is more.
Appreciate the response and apologies on the delay in response. Yes the pictures of the tumbler is from a thermoflask. Those are my junky test bottles.
So increase the intervals and lower the power. Does speed factor into it?
I’ll have to look into your sublayer set up. I haven’t dived that deep into LightBurn just yet.
yes it does. I added a post here to explain and to update my original referenced post and thread. Yeti tumbler etching - #8 by bLouChip
@bLouChip I appreciate the advice! I’m going to work my way through making a sublayer and try a couple test runs to see if this works for me. I’ll have to post on how it turns out.
It seems to wander as soon as I go into the 2nd part of the crosshatch. And I still notice the striated lines in the design
re. laser tracks or lines in etched image- I believe a smaller interval will solve that; again I use 0.09mm interval because my fine focus dot size is 0.13. I setup a test pattern being a simple 10mm sq on the cylinder, you can make many of those with variance in settings, I did them one at a time.
It doesn’t look like you have air assist, which I use and I believe it helps the process, especially if doing 2 passes or crosshatch.
It seems that the ablated image is leaving shinny stainless steel, is that correct ? If so, seems like the power and speed are correct.
re. the “wandering” or shifted image- I’m going to assume you have a roller rotary. I use a chuck. The difference being a chuck will not allow axial movement, whereas I can imagine a roller could allow that. are there locking rings on one of the rollers that could sandwich the cylinder (tumbler) on either end of a roller ? If not, perhaps two rubber bands spanning the rollers would have the same “sandwich” effect ? If none of those, perhaps don’t do the crosshatch pattern.
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Lou, +10 on the interval. I was going to post the same thing (I had the same issue with the same resolution) when I saw the OP’s settings, but I held my tongue, assuming someone with greater experience would chime in. Thank you for being that voice of experience, as it reinforced what I was thinking.
@bLouChip it does have the shiny stainless but still has the striated lines. I feel as if it almost grooves the stainless.
Yes I do have a roller but no stops. Rubberbands would be a great idea but I don’t have enough roller to do a sandwich.
I tried a sample with a smaller interval but not much change with the striated lines.
Now perhaps the wandering has something to do with my rotaries mm per rotation not being exact? I’ll have to play with that. But it looks as if it curves. I even adjusted the white space speed down to 1500 rather than the higher number which cuts down time to see if that helps but no change.
When I first had issues a little while ago I had someone mention higher speed lower the power bc my first attempt ever was at 100power 
when I first got my rotary.
I did this sample which turned out great but still has these light lines. This was bi directional, no crosshatch, 1600 speed, 60power, .050 interval. It turned out great on this one and another style line this but I tried a different material tumbler (more rubbery) and it ended up showing the lines and such…
These mug are all my test mugs lol I can’t sell etched tumblers until I figure out my settings.
This might be a little bit out from left field, but there might be some nuggets of info you can use. I have two rotaries (a lathe and a roller style) and the roller produced the same type of lines on my tumblers. The drive and driven gears were the same size (1:1 gear ratio) and even though the settings were correct I could not get rid of the lines. I was able to solve it mechanically by increasing the diameter of the driven GT2 gears (first pic), which gave me a higher gear ratio. I had the same issue with my lathe rotary (second pic). I wanted to use a mid-range diameter driven GT2 gear and then just change the object diameter. This ended up giving me lines on larger diameter tumblers, so I went back to using gears that were the same size as the tumbler. The pictures will explain it better. I’m using the same speed, power and interval settings as you are, but mechanically both rotaries were moving to far with each step for the beam width to cover (I have a 5.5w OLM2 Pro). Short of changing your rotary physically, playing around with the mm per rotation or roller diameter may shorten the step distance between each line. This could throw something else out of wack, but I don’t think it wouldn’t hurt to experiment with it a little. I’m sure someone like Ed or Lou will chime in. I have a friend with the same roller rotary I have, and his solution was 2mm out of focus and 351 LPI. I tried that but still had lines in the engraving. I don’t mean to rag on the style of roller rotary you have, but the first thing I did was cannibalize the stepper motor from the one that came with my laser and build another lathe style rotary with it. I’m also considering the possibility of getting a chuck rotary. Just my 2 cents for what it’s worth. Sorry for the long post.
@DecalDesigns , I recommend you etch 10mm squares with varied settings on a cylinder to fine tune the etch. Keep it simple, don’t crosshatch, just Fill (scan) at 0 degrees, which should have X doing the scanning/rastering while rotary simply indexes the cylinder at the interval amount.
A couple of observations overall:
- I can’t find an “aufero laser 2 20w diode” that you mention in your original post, so I’m not exactly sure what your model of laser and specs that you have. If you can clarify with an exact model number, please do. Your laser seems to behave as if its more powerful than mine, so my settings may not work for you. But in general, less power = better results in this etching situation of ablating plastic off of stainless steel.
- It appears that you have a finer focus laser than I do, so your interval will be smaller than 0.09mm but you seem to be trending that way already, good choice, keep going if necessary.
- @bionicback321 makes a great point re. the gear change on his rotary in that axial scanning (X axis in the usual rotary orientation) requires that the rotary axis can step at the interval dimension at least. So in his case, a larger roller gear/smaller drive gear will increase his rotary steps/deg, which is how it is configured in grbl, steps/degree. Now factor in that the larger the cylinder that you intend to etch, the greater the circumference, so the less steps/mm when converted to circumference distance. So big circumferences need big rotary gears, little drive gears. You should calculate your steps/deg. and steps/mm to ensure your rotary setup can attain the interval you need with your laser dot size. For example, in my machine case, my rotary is 13.333 steps/deg, so a 114.6mm dia (x Pi) = 360mm circumference = 0.075mm min interval (1 step), and I believe the last yeti tumbler I did was right about that diameter so I just squeaked in on the interval range at 0.09mm setting.
- an alternative to getting more steps/deg is to detune/defocus your laser focus to have a larger “dot” (or rectangle) hit the surface. But if you have the long focus laser model, your going to hit a wall doing that too since it has a long depth of field. I’m in that boat. But if you can defocus, then you’ll need more power than if it was fine focus. How much more, you’ll have to experiment with it (back to 10mm test squares).
- lastly, some stainless steel finishes are “spun” when polished, so there are bare metal fine radial lines around the cylinder, just be aware that those are not confused with laser striations or tracks.
You’ll make good progress testing.
Ok test square can definitely happen. I’ll get another sacrificial bottle
Ok so I tested a deep blue takeya bottle (I’ve been told blues are harder to engrave with a diode) I did the first test with a setting that worked on the grey bottle (1600spd,25pwr,.050interval) and it still left a tad bit of residuey material. A blueish hue for say. I upped the power to 32.5pwr and got this result
Not bad at all and it’s shiny too but if you look close those vertical lines are there still which discussed in previous the post test blocks to narrow in the settings could help.
@bLouChip here is the specs on my machine
LU2-4-LF Long Focus Laser Module – Optical Output – 4,500-5,500mw Is the laser I have.
Good info re. the laser specs.
re. results photo at 1600mm/m, 32.5%pwr, 0.05mm interval - was that 1 pass Fill at 0 degrees scan angle ? I see vertical and horizontal “tracks”.
Still no air assist I assume ?
Did you calculate your steps/mm in this cylinder case ? and is 1 step at least as small as 0.05mm ?
I also want to add that your latest tumbler job does look very good. Well done. And the seemingly horizontal “tracks” could be that “spun” finish effect on ss. The image edge lines are fantastic, very sharp.
@bLouChip correct, It was one pass 0 degree scan. If you zoom in close yes you can still see those “track” marks. But on this tumbler image it’s not terribly noticeable.
I still don’t have the air assist yet. I have the nozzles and hose but not a pump. Would an aquarium air pump suffice?
Would the air assist benefit the engrave? Besides removing debris that is.
Thank you. This bottle turned out very well I thought. I still would like to dial them in so I have no lines at all but I think that’ll be a sacrificial bottle adjusting settings with those 10mm squares.
I’m not sure I’ll be diving into the gear ratios on the rotary tool just yet. I’d really like to upgrade my laser as well as go to a chuck setup but I need to make a little more in my business before go that far.
You’re welcome, glad to help.
re. aquarium air pump, I believe the answer is yes based on recommendations from several experienced users in this forum. I use a shop air compressor because its convenient to do so, and it is very dry air which is important if using a beam-through nozzle so you don’t pollute the laser lens. I usually use 25-40PSI and the SCFM is very small based on the cycling of my air compressor, perhaps around 0.5 SCFM, if that helps.
recall that you may be able to de-focus your laser somewhat to make a larger “dot” if that helps with the interval setting.
When engraving the air assist helps keep the lens clean (it’s primary job) and the soot off your project. When cutting it really helps cut down on the number of passes you need to make (again, by clearing away the soot) when cutting something like 3mm or 4mm plywood. I have a 60L/Min aquarium pump, but if I were to do it over again, I would go with something like this Amazon.com . You want at least 70L/Min or bigger, I cheaped out and got the 60 and now regret it. I’m running a big shop compressor on my CO2 laser, but I think these aquarium pumps work well enough on the 5.5w diode lasers… My OLM2 Pro is in my office (in the house) and I only do engraving. I leave the cutting to the CO2 laser in the garage. That last tumbler looks nice!