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View Full Version : Q-Switched vs MOPA - A Common Sense Discussion



Jacob John
07-29-2017, 3:43 PM
I know, yet another fiber thread, but hear me out. I've been reading for weeks, gathering quotes, talking with vendors, etc., and I cannot find anyone that provides what I consider to be a clear, common sense explanation as to one vs the other.

Here's what I've been told so far, by both Chinese and Western manufacturers and salespeople:

MOPA is only really better than Q-Switched if you're engraving on plastic.
MOPA is better at producing colors on various metals
Q-Switched is just as good as MOPA on colors/metals
You only need MOPA if you're interested in finer graphics, and Q-Switched produces good graphics, but MOPA allows for more intricate details


If I can remember a few other things I'll post them, but as you can see, they are all over the place. Yes, some of it is simply trying to sell their equipment, but with an average of $3K-$4K difference in price between MOPA vs Q-Switched, I want to know bottom line, is MOPA worth it? This doesn't even begin to touch on the SPI, IPG, Raycus debate.

As a side note, I saw someone as Triumph is a specific fiber they were selling is MOPA/Q-Switched, and this was the answer: "We use JPT laser which is mopa structure and pules width fixed as 200." What? Is it or is it not MOPA? Seems like there would be a clear answer.

BTW, I've gathered around 15 quotes, and it's all over the place with pricing.

Anyone else experience this while researching their purchase?

Bill George
07-29-2017, 5:14 PM
FYI with my Ray Fine fiber (Raycus ) I can engrave text so small you will need a magnifying glass to read? So what are you trying to accomplish? Color with a fiber as I understand is very iffy and must be dialed in for each material. Time consuming and who pays for your experimenting for each job?

Jacob John
07-29-2017, 6:07 PM
It's not what I initially want, but I would still like the option. But for $3K-$4K more, it might not be worth it right now. I'm really at this point trying to understand the precise differences between the two so that I can make an informed decision. And the companies are all over the place on why MOPA is either better or not.

As far as experimenting, I would buy materials and slowly and methodically go through and record settings for my desired marks. This is well before I would offer my services to anyone. Thanks!

Jacob John
07-30-2017, 11:19 AM
Can anyone take a shot at explaining this statement from a well known manufacturer? "The laser source is JPT laser which is made by Mopa STRUCTURE which is ^more^ advanced than q-switched. Buy you can't mark color on stainless steel because the pulse width is fixed."

So I know that JPT is obviously the source, but what else do they mean? That it's not a Q-Switched, not a MOPA, but built on the MOPA structure? Any fiber guys want to try and explain? :D

John Lifer
07-30-2017, 7:28 PM
John, I dont know. This is the 20watt model I have and I can do black on stainless. No color. Titanium, yep, can get a pretty blue along with a few others. 200nm fixed pulse. I'm not concerned at this point, it is hard enough to get good setting for black, let alone colors. If you are in production and run same item repetitively, then it makes sense..otherwise go full Mopaand play with it or fergit color.

Jacob John
07-30-2017, 7:41 PM
John, I dont know. This is the 20watt model I have and I can do black on stainless. No color. Titanium, yep, can get a pretty blue along with a few others. 200nm fixed pulse. I'm not concerned at this point, it is hard enough to get good setting for black, let alone colors. If you are in production and run same item repetitively, then it makes sense..otherwise go full Mopaand play with it or fergit color.

But what about the inconsistent remarks about MOPA vs Q-Switched? I'm more interested to understand if the $3K-$4K difference in price is really worth it. Reading another thread here, not many people get requests for color marked items. But beyond that, if that's all MOPA is really better at, I can't justify the increased cost. :)

Jacob John
07-31-2017, 12:47 PM
Posted in the wrong thread, but if I'm trying to get a consistent black mark on stainless steel, Q-Switch or MOPA?

What about silver?

Found a good thread talking about stainless and black marking with a MOPA. Still a head scratcher, but not as confusing. http://www.sawmillcreek.org/showthread.php?247354-Fiber-Laser-question

Kev Williams
07-31-2017, 7:57 PM
In checking (one set of) my fiber's parameters,
I found there's not much that's NOT grayed out on this page;
only the min & max PWM settings are variable--
365069
--and all THEY do is put a limit on the min and max
numbers you can enter in the frequency settings
in the main settings. I have yet to figure out what
the ACTUAL minimum and maximum values really are!

--but change 'fiber' to 'yag', and the board lights up--
365070
-note 'Q-switching' can now be 'adjusted'...

What this tells me is that my fiber doesn't have Q-switching capabilities. OR that they're they're not variable.

I know what a MOPA can do. I have no idea what Q-switching can do, or what you call MY machine with apparently neither! ;)

Jacob John
09-11-2017, 1:34 PM
I still feel lost in this discussion. :D

So would a 50 watt cut sterling silver easier than a 30 watt? Remember I asked ease of cut, not speed. I know someone that has a 50 watt and it cuts, but slowly.

Scott Shepherd
09-11-2017, 1:59 PM
That's the problem isn't it? In order to get pre-sale support that answers questions that keep you from buying something that doesn't work, you need to buy it from a dealer that knows their stuff and knows the answers. Want to be able to talk to people who know, you have to spend the money to go with a name brand. Want to guess and what it might or might not do, and you end up with Chinese machines. I'm positive people like SPI and IPG can help. But you don't see many SPI sources in Chinese machines, so what they tell you probably won't apply to a source that's a knock off of their source.

Jacob John
09-11-2017, 2:02 PM
I feel like we're all guinea pigs when it comes to galvo fibers.

Scott Shepherd
09-11-2017, 3:43 PM
I feel like we're all guinea pigs when it comes to galvo fibers.

Correction, we're all guinea pigs on fiber lasers when you buy from China. Trotec has full support for their Speedmarker FL's.

Kev Williams
09-11-2017, 8:27 PM
I still feel lost in this discussion. :D

So would a 50 watt cut sterling silver easier than a 30 watt? Remember I asked ease of cut, not speed. I know someone that has a 50 watt and it cuts, but slowly.
Tim's been having fun with his 50w, it seems to be so efficient that it needs to be tempered down by either lowering power, changing frequency or a combination of both. He's going to have a great time with it once he gets everything dialed in! :D

I tried to cut thru a .010" thick stainless sawblade awhile back, it was 3" diameter, my customer wanted it 2-1/2" diameter. No problem, I'll just draw a 2-1/2 circle and let 'er rip!

Yeah, right ;) - the problem, was that as the kerf got deeper, the metal began to melt back into the kerf behind the beam, much like plex does when trying to cut too deep with not enough power. So my 'ease of cut' was dependent on the depth of cut and how much room there was for the beam. Had I started cutting the sawblade with say, 5 circles spaced .015mm apart for a few passes, then reduced to 4 circles, then 3, etc,-- by the time the laser was finally thru the cut would've been much cleaner and just better overall because the first cuts would make room for the beam to fit down to the bottom of the cut. The slight bevel probably wouldn't have mattered. The way I did it, the metal WAS cut thru but the melted slag held it all together. And oh, was it warped!

It took nearly a year for me to learn the most important lesson in getting good results with my fiber... Have Patience... One of my repeat jobs is an aluminum lid with several words and symbols, requires .004" depth by laser. I've tried a zillion different arrangements of settings to get me to .004" deep in the shortest amount of time. No matter if I go slower and less passes, much faster and more passes, and every combination in between, my time to an acceptable depth is between 4:40 and 5:00. Any less time spent than 4:40 and it's not deep enough. And working settings between the 4:40 and 5:00 marks I can get an increase in the quality of the engraving without a depth increase. I've given up trying to find a faster way :) -The routine I run now goes 5:17, insurance that I'll never get any parts NCR'd because they're shallow. I just work on another job during those 5 minutes...

John Lifer
09-11-2017, 11:34 PM
Yep, you should have seen the look my wife gave me when I mentioned I should get another fiber to not waste time when I was running a 4 min cycle..... I'm not nearly thinking about it now.

Tim Bateson
09-12-2017, 12:36 AM
I'm still stuck in Florida, but hope to be home & doing additional testing in a few days.

Jacob John
09-12-2017, 11:44 PM
Has this been posted yet?


https://youtu.be/7VARS8p29ms

Kev Williams
09-13-2017, 12:44 AM
Looks like fun, but those are the types of machines company's buy to do their own mass production laser engraving instead of coming to US for it ;) -- They even brag that Smith & Wesson and Springfield Armory use their machines. While I could make great use of one of those, I'd never be able to afford one... even with my workload it would take a few years to hit break-even and actually start seeing a profit. My fiber covered it's cost within 6 months. The Yeti-type cups and whiskey flasks they're marking in 14 to 17 minutes, charging enough to cover that much engraving time is a hard sell, and most of those are 6 minutes work via Cermark...

Yup, as much as I'd love an Austin Martin, the Mustang GT will have to do! :D

Mike Null
09-13-2017, 7:51 AM
Kev
You're not allowed to buy one of those until you learn to spell it.:D

John Lifer
09-13-2017, 9:11 AM
Nice, Actually If a person were really good with electronics, steppers and controls, I'd bet this would really be something pretty easy to cobble up.
But not me for sure. Think of turning the rotary into a flat, just long x step rather than turning rotary. This is all that is happening, at least in the video. Now add Y movement driven by controller, that's a different thing. (but that video didn't show that happening)

Matt McCoy
09-13-2017, 11:14 AM
Nice, Actually If a person were really good with electronics, steppers and controls, I'd bet this would really be something pretty easy to cobble up.
But not me for sure. Think of turning the rotary into a flat, just long x step rather than turning rotary. This is all that is happening, at least in the video. Now add Y movement driven by controller, that's a different thing. (but that video didn't show that happening)

Software would be a challenge. Good for a conveyor-belt application.

Kev Williams
09-13-2017, 2:25 PM
Kev
You're not allowed to buy one of those until you learn to spell it.:D
force of habit-- and shows just how far down my 'yeah, right' ladder an ASTIN Martin is ;)

I had a guy from some laser outfit in Calyfornya call me a few months ago, quoted me 'about' $3500 to build a simple XY-gantry, with software, using my Triumph parts. Been waiting for him to call me back...

I've toyed with the idea of picking up a 20w cheap Ebay fiber like mine and doing this myself; I have the two XT machines, the one is pretty much proprietary to one customer, which is ez enough to change. These machines, unlike most CNC's these days, has a moving spindle carriage, with about 2-3/4" inch of vertical travel. Add that to the 3-1/2" of spindle head travel, and that would give me a great range of focus. Mounting the scanhead to the spindle head would be a simple matter of cobbling together a bracket to hold the thing. Taking into account the space the scanhead would eat in the Y axis, I'd still have 24" of X travel and about 15" of Y travel. The main jobs I have in mind for this would be operator panels I currently do by C02, mostly text, and small graphics, meaning, it would be easy to piece together 'sections' that would fit within the 6" scanhead limits. Each section would have to be moved into position in EZcad, and then the machine moved to match. it would be 'manually operated' to be sure, but I'm already moving the same kinds of parts by hand manually, and aligning each section by redlighting. The XT table moves could be entered as a job requiring nothing more than pressing start & pause. The routine would be run 1st section/move 2nd section in position in EZcad/start-pause/run 2nd section/move 3rd section into position/ etc... I'm actually pretty certain the job sections can be setup in EZcad to change themselves, and using the 'flymark' function, the fiber could tell the XT when to move..

If only I wasn't planning on semi-retirement in less than 2 years... ;)

John Lifer
09-13-2017, 10:44 PM
Build one and we will come:)

Jacob John
09-13-2017, 11:23 PM
Let's just all pitch in, buy one, and "Share" it. :D

Jacob John
07-29-2018, 4:03 AM
Ooof, I really hate to dredge this thread up, but I need some advice. I have a lead on another laser, which would be an upgrade in power, but I don't think it's a MOPA, like I currently have. In reading, there still seems to be some debate about a MOPA's abilities such as:

1. A more precise, better detailed engraving when compared to a Q-Switched
2. Brighter whites on metals

Like most, I have no use for color on stainless, and haven't had any requests for it, but these do concern me. I've gotten used to my MOPA, so I'm scared I won't be as happy because of the above points being argued. Here are the specs of the one I'm possibly getting (50 watt): (Any advice is appreciated)

390549

Is "pulse" still considered Q-Switched? I know it's a common reference name. This fiber is also an SPI source like my MOPA.

Floyd Siegal
07-30-2018, 7:09 PM
As for cutting, there is no real advantage to using a MOPA laser source. There are a couple of standard JPT laser sources that are considered MOPA lasers. The M1+ version is a MOPA but with a fixed 200ns pulse width while the M6+ (more expensive) allows you to control the pulse width. Advantages of any MOPA system is that they are more stable and tend to have better specs...beam quality, quicker response times, greater Frequency ranges, better quality at a cost. If you want to do colors on Steel you don't have to move the focus to achieve it. You can get a better dark engraving in aluminum, you can get some lighter engravings in some black plastics and the quality of the engravings are cleaner and sharper if you really, really, really look hard! Good luck trying to see the difference.
We always use a JPT 60W set-up (M1+) for cutting, cheaper and no performance difference vs the M6+.390660
Depending on the thickness, material, and curve distance the cutting times can vary quite a lot. This photo shows 2 1mm thick Silver name tages. The top one took about 6 minutes, the bottom one took 10 minutes.
Floyd
You can watch the link
https://www.linkedin.com/feed/update/urn:li:activity:6429786205239545856

Jacob John
07-31-2018, 1:11 AM
Thanks Floyd. We'll be cutting for sure, but for etching, we'll be etching stainless steel and sterling so I want to make sure it looks top notch. I know my MOPA does a nice job. Did the specs I posted above look decent? I'm told it's an SPI source so I know it's at least a quality laser.

Floyd Siegal
07-31-2018, 2:23 PM
Hi Jacob, I think the laser source is a good one and has a good reputation but I don't have any experience using SPI. According to the specs, I'm sure it will work well for you.

Mike Mace
09-09-2018, 5:37 PM
Jacob, I'm kind of in the same spot you were a year or so ago....I'm trying to figure out if I should go with a Q switched, MOPA M1, or M6....I'm mostly looking for light stripping of annodization, and light engraving. Think AR lower receivers and pistol slides. I'm not sure what types of machines people are using on the videos out there where plastic magazines are black, and turn a tan-ish color when hit with the laser. I understand it takes quite a bit of dialing in to get into that narrow band of "working" but I want to make sure whatever machine I purchase has the ability to hit that band. Any thoughts?