Question about clarity - Western vs Chinese lasers

[Brian W Evans]

I am still researching / thinking about buying a CO2 laser engraver. I spent a few hours with a Trotec rep last year and, of course, am very impressed with their machines. However, the price tag is also impressive.

One of the general opinions I'm seeing about western lasers (e.g. Trotec, Epilog, Universal) is that their ability to render text, images, etc. cleanly is greater than that of Chinese lasers (I am specifically thinking about a Rabbit RL-80-1290 or similar). Is this still generally true? If so, how big is the difference? Is there anything I can do to improve on a Chinese laser's rendering clarity / crispness (not sure of the right term)?

I know that a lot depends on the quality of the original image or vector file and on the material. Let's say I intend to mark quite a bit on wood, acrylic, and metal (with cermark or similar). I would also like to do some glass and stone. I plan to do both raster and vector work and am proficient in several graphics programs. One thing I plan to do a lot of work with is maps, where fine details will be important. Raster images of people will also be important.

I plan to make items for sale, and possibly do some engraving jobs for others. Money is a factor but not necessarily the deciding factor. Throughput is not a factor either. I will not be running the machine all day every day.

I'm really just trying to find out the difference in rendering ability. If anyone has pictures they could show, that would be amazing.

Thanks.

[Wojciech Szul]

Very hard to answer. Mostly - because quality of engraving/cutting is hard to "compare" without having 2 pieces from different machines in hand. Pictures are NOT good enough - in my opinion.
If you plan to use extensively small vector engraving as maps - you can be surprised how long it will take on Chinese machine. They are slow. On basic Chinese machine you can expect resolution around 127dpi for bitmaps. You can go further, say up to 254dpi or even higher, but there are few limits: width of the beam, material "response" (how it burns - different stone and paper) and time. As a sample A3 bitmap engraving on DC machine will take an hour at speed 150mm/s range. Keep in mind vector and bitmap engraving have different "look", "feeling". Can't interchange them easily, and sometime - just have to decide to one of them due look. On some materials widening vector beam does not make same effect as engraving bitmap. On other - you can try to do this. Long story.

I was working on both - Western (for a while) and Chinese. Probably best way to estimate is a make a one WHOLE design (and vector and bitmap combined in one design) and go to companies where they can be done - under your eye. You will see how long take particular job and what level of quality you can achieve.

[Bill George]

Brian if you do a little research here you will find if your doing a lot of engraving time wise the Chinese machines generally lose. Quality if you slow down the Chinese machines they do just as well. Cutting I think they are both about the same. Its your call.

[Brian W Evans]

Thanks, guys.

Time wouldn't be an issue at first. If I become successful enough that it does become an issue, I have no problem buying a Trotec or similar.

I have some samples from Trotec and Epilog and have access through friends to a Universal and a Chinese machine. I will take Wojciech's suggestion and make some projects to compare.

On a separate topic, I envy you living in Ireland, Wojciech. I was fortunate enough to spend about 7 weeks there a few years ago and quickly fell in love with the place and the people. My wife still wants to move there.

[Kev Williams]

I have a big 1390 80w Chinese Triumph, and as far as text and 'basic' graphics go, @ 1/16" or larger I'll put it up against any of my Western machines. However, that quality comes at 25% of the speed.

But "clarity" in other areas, no contest. This pic, done on hard anodized with my Gravograph LS900, will fit nicely on my thumbnail...
smpic.jpg

My LS900 also reproduced this photo of part of my basement shop onto some laminate, very highly detailed-
AbyssOrig(Custom).jpgTheAbyss(custom).jpg

--I've never gotten anywhere near these results with the Triumph. But for what I DO do with it, it does it very well!
tr1.jpgtr2.jpg

===========================

[Brian W Evans]

Kev,

Thanks for the response. I can only see two attachments, though - both of a control board of some kind.

[Ross Moshinsky]

The spot size on my LS100 30W is bigger than the spot size on my VLS 6.60 60W. Most of the time, you can't see the difference. When I can see the difference is on small/very small text typically found when I'm running a detailed logo. The other time I see it is when I'm engraving something where it's a black text box with white text. It will "eat into" the text. It happens on both machines, but it's more pronounced on the VLS. Tweaking the stroke solves the problem more often than not, but it is something you can miss if you're not on your game that day.

Personally, I wouldn't recommend a ULS machine at this point. The software is pretty good but the actual machine is mediocre. The drive system is a joke compared to many of the other manufacturers. It's not much better than a Chinese machine to be perfectly frank. They also doubled or tripled the cost of a recharged tube. It used to be a big incentive to be able to pay about $800-900 to get a recharged tube that you essentially slapped into the machine and you were ready to run.

At the end of the day you need to make a list of what's important to you. If engraving is your #1 priority, it's very likely that a "Western" machine is going to be the best choice. If it's 50/50 engraving vs cutting, it's a harder choice. If cutting is your main objective, a Chinese machine becomes a very valid choice. I can tell you I engrave "easy" to engrave materials most days and I run the LS100 still on most of the jobs. It's only 30w and has a tiny 12x18 table but it engraves 30% faster and produces a better end product.

[John Lifer]

I quoted a large map a bit ago. A local city wanted a 1920's era street map of the oldest map they had showing the original incorporated area. Size was max + of my 1300x900 machine, roughly 42"x48".
Was going to be on stainless steel, cermark. So it's slow anyway. if I reduced down to my 35" bed depth, (35"x42" if I remember correctly) it was going to take about 8 hours to cover the entire sheet. about 10 hours if I did their original size and move the piece. Long single run time and with cermark, don't know how much shorter time a US made machine would have been. If it had been onto wood, then a Trotec/epilog would probably cut that time in half, maybe more, IF it would fit in their machine.

UH, I didn't get it, priced myself out of the work. But hey, not giving it away.

[Kev Williams]

I kept getting logged off while posting the thread up above, looked okay when I posted-- I've fixed it I hope

[Gary Hair]

Just my opinion - you have three machine variables with Cermark and how fast you can mark. First - wattage. The higher the wattage, the faster the speed - up to a point anyway. There is a point of diminishing returns, just like trying to bake a pizza at 4500 degrees for 3 minutes vs 450 for 30 minutes... Second - spot size. The smaller the spot size the higher the resolution - limited by the motion system of your machine. Lastly - power density. This is also related to spot size. An 80 watt laser with a spot size that is twice the diameter of another 80 watt machine will have significantly less power density and will negatively impact the maximum speed. Using all of this should mean that a "mainstream", metal tube laser should give you a better mark at a faster speed than the typical Chinese, glass tube laser.
Other things that impact engraving time that are not machine dependent. White space - the more white space that you have between marks, the more time it will take to laser. Often times you can break up your engraving into smaller pieces and reduce your engraving time significantly. Raster vs vector - anytime you can vector a line instead of rastering it will save you time. It's possible to use Contour in CorelDraw and create stepped vector lines that will look like a wider line that has been rastered. Again, saving lots of time especially if there is a lot of white space - think large rectangle. Sometimes simply rotating your design 90 degrees will give you faster run times. I had a large stainless plate, 32" x 20", and using these three techniques took an 8 hour job and reduced it to just over 2 hours! It took me about 2 hours to setup the file but I still saved 4 hours! I charged the customer for 6 and he was happy that it was much less than the 8 hours I originally quoted - win/win!!

I quoted a large map a bit ago. A local city wanted a 1920's era street map of the oldest map they had showing the original incorporated area. Size was max + of my 1300x900 machine, roughly 42"x48".
Was going to be on stainless steel, cermark. So it's slow anyway. if I reduced down to my 35" bed depth, (35"x42" if I remember correctly) it was going to take about 8 hours to cover the entire sheet. about 10 hours if I did their original size and move the piece. Long single run time and with cermark, don't know how much shorter time a US made machine would have been. If it had been onto wood, then a Trotec/epilog would probably cut that time in half, maybe more, IF it would fit in their machine.

UH, I didn't get it, priced myself out of the work. But hey, not giving it away.

[Brian W Evans]

I kept getting logged off while posting the thread up above, looked okay when I posted-- I've fixed it I hope

Yup. Fixed. That's an amazing photo of your shop - great detail. Thanks for sharing.

[Wojciech Szul]

On a separate topic, I envy you living in Ireland, Wojciech. I was fortunate enough to spend about 7 weeks there a few years ago and quickly fell in love with the place and the people. My wife still wants to move there.

If you will be in Ireland again you are welcome to visit my workshop and see how it works. I'm between co. Kerry and co. Limerick, so it is very scenic part of Ireland (Wild Atlantic Way). I moved here over 12 years ago and love it (maybe except typical Irish weather ). Unfortunately laser business here is not easiest way to earn money.
Anyway, back to the thread: prepare two most typical samples of your work - say one engraving picture/map and second some cut with combined engraving which will tell you what and how can be done. It's worth to spend extra few $ to see how it is done in practice - and not by seller technician, but by person who is in business. Lasers are NOT 200$ toys and you can regret when you miss something important.

[Brian W Evans]

Wojciech,

Thanks for the invitation. I will take you up on it if I get to go back to Ireland again. Thanks also for the good advice.