My review of buying a Triumph laser.

[Robert Silvers]

I decided that I wanted a laser cutter/engraver. There are many sizes available, and I settled on a 900x600mm with 100 watts of power. A US made one of that size and power would be about $42,000. My costs, including customs tax, shipping, final residential delivery, and wire transfer fees came to about $5850. I then paid a friend about another $300 in wiring, ducting, electrical work, etc.


There is a middle way to go - where you buy from a US company who imports and re-badges Chinese lasers. This is for people who don't feel comfortable working with other countries directly and are seeking (but maybe or maybe not actually getting) more support. Going that way would maybe be in the $12,000-$15,000 range.


I had to pick a brand, and there are many. I went with Triumph.


Timeline:


7/11/13 - First contact. Decided on features.


7/30/13 - Settled on exact features, got invoice.


7/30/13 - Send payment by wire (I sent the full amount up front. Some people send partial until it ships).


8/3/13 - They shipped machine.


9/30/13 - It arrived at my house via truck.




The laser company arranged the delivery - I didn't have to do much. They asked me to sign a customs broker form giving power of attorney to represent me. I did. The payment to the laser company handled everything except for about $300 in custom's tax.


Some things to consider:


Get a real chiller. Don't listen to the idea of using a 5 gallon pail of water. The model 3000 is just water, radiator, and fan. The model 5000 adds real refrigerant-based cooling. The model 5200 doubles that capacity again. I have the 5200, and I have never seen my water temp go up by more than a few degrees C. Even the 3000 would be vastly better than a bucket of water as far as having a sealed system that does not need much cleaning.


I suggest to make sure that every detail of what you want is on the invoice before you place the order to prevent any misunderstanding.


Software -


Mine came with software called PHcad. I like it a lot. You can use it directly, or it can work with Autocad, Corel Draw, or Adobe Illustrator. This software is the same as Thunder Laser's LaserGrav software.


Support -


My first support email was that the laser was not having its power set correctly. They responded two days later, and apologized for it being a Chinese holiday and for their slow response time. They correctly fixed the problem by showing me that I didn't set one needed parameter.


My second support issue was that the software crashed when loading files. They said that the version I had only worked on XP, and that for Windows-7, I needed the newer version. They sent me a download link, and the newer software fixed that.


I am happy with support so far.


About laser tubes:


You can get a generic tube, or a premium brand. I got the premium RECI. I highly suggest that you specify the tube that you want by model number, and not by wattage. This is because some people speak in terms of average max wattage, and others talk about peak wattage. My tube is 100 typical and 130 peak, but it is better to call it a "RECI Z4." Note that the Z is newer than the W, so ask for it by name.


About power:


The laser is 220 volt. They will sell you a 110 volt conversion, but I opted for 220. I asked for the chiller to come as 110 volt, and it did. The blower and compressor came as 220, and I needed to wire up some outlets. I have the laser always getting power, as it has its own switch, and the blower and compressor are on a double-pole light switch that I mounted in a box on the bottom of the laser unit.


So far I love it and aside from getting the old version of the software at first, I have had no problems. It came with the laser tube already installed, and it was correctly aligned.






Marking ceramic floor tile:


https://www.youtube.com/watch?v=wUQyvLk9G7I






It is said that C02 lasers cannot mark steel unless you buy special marking ink that is very expensive. I have had no trouble marking steel, though it is not as good as a Fiber Laser - so don't buy a C02 primarily to mark steel. It cannot cut metal.


http://imageshack.com/scaled/800x600/191/eihj.jpg


My invoice - I had about $300 in customs tax charges on top of this:


They included a nice gift:


http://imageshack.com/scaled/800x600/4/vpgb.jpg


Tube is giant:


http://imageshack.com/scaled/800x600/15/nbv6.jpg


I paid $100 extra for "residential delivery" (no loading dock). The delivery company accidentally picked a truck with a small lift-gate. Had to uncrate it on the truck.


http://imageshack.com/scaled/800x600/163/m5yx.jpg


Z4 tube (latest):


http://imageshack.com/scaled/800x600/850/0nxd.jpg


Chiller 5200 (would be fun to use this to water-cool a PC):


http://imageshack.com/scaled/800x600/706/oese.jpg


Big work area, without being giant. Unit is about 600 lbs but has wheels:


http://imageshack.com/scaled/800x600/443/jn8x.jpg


Made custom Milk Bones for my dog to practice the "matrix" feature (marking multiple objects with the same thing:


http://imageshack.com/scaled/800x600/62/yu2b.jpg


Yes, it can mark tool steel:


http://imageshack.com/scaled/800x600/706/5wqz.jpg


I paid a friend $50 an hour to redo my hook up work. It took him several hours, and $150 in parts. So that was like $300 more. We put a 4" dryer vent in the wall (6 inch is better):


http://imageshack.com/scaled/800x600/855/80ar.jpg


Inlayed wood sign:


http://imageshack.com/scaled/800x600/443/i7o7.jpg


Box:


http://imageshack.com/scaled/800x600/513/p53s.jpg


Engrave the back of a mirror:


http://imageshack.com/scaled/800x600/12/25zc.jpg


Software:


http://imageshack.com/scaled/800x600/9/qln7.jpg

[Jeff Belany]

You look like you have a nice machine. I don't quite understand how your CO2 laser is marking steel so well. I used to run a 100W machine and could use barely (and I mean BARELY) make a mark at all, even with full power and very slow speed and multiple passes. I hope someone chimes in about this.

Good luck.

Jeff in northern Wisconsin

[Mike Null]

You can mark stainless with a machine as low as 30 watts. The problem is that it is hard to regulate and you may end up burning or distorting the steel.

[Dan Hintz]

You look like you have a nice machine. I don't quite understand how your CO2 laser is marking steel so well. I used to run a 100W machine and could use barely (and I mean BARELY) make a mark at all, even with full power and very slow speed and multiple passes. I hope someone chimes in about this.

Good luck.

Jeff in northern Wisconsin

High carbon steel... carbon is what gives you the mark, so 100W is reasonable at slow speeds to give you a decent mark, assuming your carbon content is high enough. Back in the days of 30-60W systems being common, marking steel directly was mostly a no-go situation... you could do it with a 60W, but you had to go very slow and use a 1.5" or the high power density lenses. Now that stronger tubes are becoming cheaper and more readily available, that limitation is slowly disappearing.

[Robert Silvers]

That first mark was at 5mm/sec and at least 90% power. But I have dark (but less deep) results at 15-50 mm/sec.

When my 30 milliamp meter comes, I will ensure that I stay at or below 26 ma and decide on what my max power can be.

Is there a way to know how many hours I am putting on the tube? Does the controller track that? Is there an hour meter I can buy that will only increment when the tube is on?

[Dave Sheldrake]

I had a meter made by Tweakie that reads the RF signature that comes with a DC tube and only increments when the tube is actually powered. It uses a sensor on the clipped to the tube body :)

Working steel with standard mirrors and lens's will likely end in a busted lens and/or a damaged tube. The lens's and mirrors aren't rated for anti reflective backscatter so reflected beams can travel back up the optical train and there is no AR coating on RECI output couplers.

272481

cheers

Dave

[Mike Null]

FWIW--I can mark steel quite nicely with my 45 watt Trotec and the standard 2" lens. It is too slow to be useful though.

[Robert Silvers]

I know copper acts like a mirror. But steel should be ok.

[Robert Silvers]

I would like that meter. Not sure how to reach him.

[gary l roberts]

Always good to see a buy go good and happy burning.

[Kev Williams]

since I'm in the market for a bigger machine, this is pretty interesting. I'm curious as to machine brands you passed on--

I've been running my old Optima 25 watter for around 14 years, and my LS900 40 watt for over 10 years, and I've done little more than just USE the things. I've never heard of measuring tube milliamps until reading posts from you guys, and I'm also curious why water cooling a laser wouldn't be sufficient? My 40 watt runs all day every day and it's air cooled, and the cooling air exiting the side of the machine never even gets warm.

Robert, did you get samples from the machines you checked out before deciding on the Triumph?

[Dave Sheldrake]

I know copper acts like a mirror. But steel should be ok.

Anything that does not absorb, reflects, at 10,600nm steel is highly reflective until you reach a few hundred watts or introduce oxygen. Polarisation becomes a problem unless you have differing waves of P polarised and S polarised beams to prevent backscatter.
I've seen a final lens and the tube on a 150 watt RECI die due to backscatter when the final lens is of the incorrect type with no phase shifting. While a DC tube of 100 watts with a good lens will mark steel (and cut steel at higher powers) it's the optical train properties that matter not raw power.


I would like that meter. Not sure how to reach him.

Just google "Tweakie CNC" the guy is a legend and has probably forgotten more about advanced electronics than most people I know combined will ever know. When he speaks I listen :)


My 40 watt runs all day every day and it's air cooled

RF tubes generate far less heat at a given rating, DC tubes rely on effectively a big high voltage arc hence get very hot.

cheers

Dave

[Robert Silvers]

since I'm in the market for a bigger machine, this is pretty interesting. I'm curious as to machine brands you passed on--

I've been running my old Optima 25 watter for around 14 years, and my LS900 40 watt for over 10 years, and I've done little more than just USE the things. I've never heard of measuring tube milliamps until reading posts from you guys, and I'm also curious why water cooling a laser wouldn't be sufficient? My 40 watt runs all day every day and it's air cooled, and the cooling air exiting the side of the machine never even gets warm.

Robert, did you get samples from the machines you checked out before deciding on the Triumph?

The tube warranty requires 26 milliamps or less. I want to make sure the power supply was set up properly.

An open bucket can cool ok (until it doesn't), but is not thermostatically controlled so the temp changes over time, and is easy to contaminate, and has to be changed more often.

I didn't get samples.

[Dave Sheldrake]

On a fatbody tube you want to keep it under 23 degrees to get the best life, 18 to 22 gives great life on the fatbodies (10k hrs+)

cheers

Dave

[Robert Silvers]

5.1mm acrylic cuts at 10mm/sec at 98% power. Any less energy is unreliable. I saw some charts online that said I should be doing 20mm/sec at 90% power. I assume my cutting speed is within the range of normal?

[Dave Sheldrake]

10mm a second @ 98% on a 100 watt fatbody is what I would expect from 8mm acrylic :( Try to keep the power below 90% or heating will become a problem.

cheers

Dave

[Robert Silvers]

For all I know, at 100% power, my power supply is only putting out 17ma instead of 26. That is why I need my 30 milliamp meter.

If I go down to 90% power, then I will have to run at 9mm/sec to penetrate. I don't understand how that makes for less heat.

[Dave Sheldrake]

It depends on what the supply is kicking out Rob, it may be 17mA or it may be 40mA, Chinese supplies aren't the most stable in the world and can spike or peak above a safe limit.

The process of pumping CO2 gas mix is based on input energy, the higher you go on the input the more heat is generated in the tube so the longer the gas takes to reach it's base state. Going up 10% on input power doesn't increase the supplied current by 10% as it's not a 100% efficient transfer.

China tends to set up machines in many cases by the cutting ability of the tube (output beam power)rather than by testing the actual supplied current, if they get 100 watts of beam that can on occasion mean over driving the tube.(not all of them by any means but some do it)
Dropping 10% on power can often increase cutting speeds due to the nature of the way lasers actually cut.(sounds silly I know but is born out by testing and the figures behind it)

Like you say a mA meter is essential at this point so you can see what current you are actually dealing with.

cheers

Dave

[Robert Silvers]

Also note that my water temp is always in the 18-22 range if that matters.

[Robert Silvers]

One thing I found interesting is that a fiber laser can put beautiful white marks onto nylon but the C02 makes much less defined black marks on the same material.

Seems like if you want to engrave plastic, C02 can do it, but it will be way less nice looking than fiber.

[Dave Sheldrake]

Depends on the plastic type Rob, fiber is 1064nm co2 is 10,600nm

18 - 22 is a great temp to run at but is only part of the story, it's the gas in the tube when subject to a more powerful arc that takes longer to degrade back to an unpumped state.

cheers

Dave

[David Somers]

Robert,

I am new to the Forum. Appreciate you sharing so much info on this purchase.

I am curious. What brought you to buy a laser in the first place?
How do you plan to use it?
Do you have graphic arts in your background?
Assuming you are going to use this for a business, how do you see this fitting in? Do you plan on this being the primary tool for your business or is this now one tool among others for what you do? Or...please don't take this to be dismissing this use....are you primarily a hobbiest?

I ask because I am eligible to retire now from my job as an IT Specialist with the US National Park Service. When I finally make the decision to retire I would like to take my serious hobby of woodturning, and make it at least a semi paying hobby. I have been looking into laser engraving for some of the things I like to do on various types of turnings. I have been pondering between the "rent time or pay someone to do the burning" approach, and the buy a laser and do it myself approach. I have a hard time seeing something like an Epilog being cost effective for me given the high purchase price, but am not sure yet. Much would depend on how often I made use of it for my work, how my wife made use of it, and what kinds of things we grew into. I will certainly start with the "pay someone else" approach for now to see what that looks like. I am always interested in how others are using this. I get the impression of lots of folks on this forum are hard core businesses based on a mix of things, not just the laser.

All that is a long way of describing why I was asking the questions I did! (I am chatty if you hadn't guessed already!)

Thanks in advance! If any of the others on this thread feel like piping up with their answers to this I will read them all eagerly!

Thanks!

Dave

[Robert Silvers]

I have a background in photography, design, and computer science. I also have a lathe, mill, welder, and other tools at home. I got it because I may sell a product that has some parts that I would have had to outsource to a company with a laser. I don't see any chance of making money selling laserable items directly as a source of profit, but think it can work if they are parts within other items.

I could have outsourced, and that is more practical - at least in the beginning, except that I enjoy it. After having it, I now know that I can rush through variations so quickly that I would never have paid someone else to spend the hours doing what I am doing with it, and would have settled for less evolved part designs. All in all, I don't find the price that expensive even as a toy, considering that other people would buy an ATV for fun.

Also my son is finding it fun to make things. He wanted a toy knife so I traced a Rambo knife and cut it out if MDF for him. So I enjoy it as a hobbyist. I have had an interest in lasers for decades and just like stuff like this.

[David Somers]

Thanks Robert! That tells me a lot, very appreciated!

Dave

[Kev Williams]

OK, a question or two for Robert, and/or anyone else who cares to chime in!

First, your thread about this laser has really peaked my interest in the Triumph. Between your experience, your pics (especially the steel marking and ceramic tile engraving), and what I've found searching around the 'net, I decided on giving Triumph a shot. I've been emailing back and forth with Triumph Lasers since last night, and have gotten pricing on models and features. I must confess the 'lost in translation' thing is a bit frustrating, but the prices for what I want are worth the gobbledygook!

So now the questions: The machine is standard with an 80 watt tube. Based on Richard's tests I at least want the 100 watt, but I'm seriously considering the 130 watt tube. My big laser is only 40 watts, that's what I'm used to. My primary use is putting text and graphics on anodized aluminum and marking SS via Cermark, and lots of Rowmark engraving-- but not so much cutting of anything- yet anyway. I've also just picked up a customer that will be needing 1/16" deep text in 4' long sections of poplar on a regular basis. Would the 130 watt laser really help much? I figure it might speed up the stainless etching and it should help with deep wood cuts, and I'd like to be able to get decent Cermark results on aluminum. I also realize the cost of replacing a 130w tube and/or power supply down the road will be subtantially more than replacing 100w equipment. Are there other issues with "too much power"?

Second question, below is a picture I send to customers who ask about small engraving- on a machine this large (48x36-ish), am I going to see nice crisp SMALL text and graphics like I get now?

Back to laser tubes-- Richard, you said you specified a Reci Z4 tube, is the 130 watt tube a different part number? I'm getting quoted using Reci tubes, but no part numbers...

Thanks everyone! That all said, I've also sent AP Lasers an inquiry, haven't heard back yet. Their "no bottom" machines open the mind up.. :)

[Robert Silvers]

Be careful. Some people call the Z4 130 watt. It is 130 peak but really 100. A true 130 won't fit this size machine. If you want more than a Z4 you need a larger machine. I can proof read any quotes for you and catch areas of concern.

[Dave Sheldrake]

Anything much over an 80 watt DC tube may be too much for routine engraving, these tubes have a minimum level they will fire at(usually 12 - 15%) and a 130 may sometimes be too much for the job at that power level.

RECI Tubes

W2:
Length: 1120mm +/- 20mm
Diameter: 80mm +/- 2mm
Rated Power Output: 80 Watts
Maximum Power Output: 85 Watts
Working Current: 27 Ma

W4:
Length: 1400mm +/- 20mm
Diameter: 80mm +/- 2mm
Rated Power Output: 100 Watts
Maximum Power Output: 120 Watts
Working Current: 28 Ma

W6:
Length: 1650mm +/- 20mm
Diameter: 80mm +/- 2mm
Rated Power Output: 130 Watts
Maximum Power Output: 150 Watts
Working Current: 30 Ma

W8:
Length: 1850mm +/- 20mm
Diameter: 80mm +/- 2mm
Rated Power Output: 150 Watts
Maximum Power Output: 180 Watts
Working Current: <30 Ma

Also remember beam quality from an RF tube is usually much better than from a DC tube.

cheers

dave

[Robert Silvers]

Mine does not really work at 10%. It works at 15%. I never tried anything between 10 and 15. I have so far not found anything where I wish that I had less power. I do want to cut things that would benefit from more power. But I only have a week's experience.

[Kev Williams]

Richard, I'm looking at the 1600x900 machine, so the bigger tube should fit--

Dave, so too much power CAN be an issue, that's what I wanted to hear, thank you! And, I note your PN's start with a "W", Richard stated his is a "Z"- Newer model(s)?

Now, as for the intricacies of lasers- Aside from watching my dad engrave and him showing me how to sharpen cutters, I'm a totally self-taught engraver, full-time since 1975. I bought our used Universal circa late 2000, and 3 years later when it wouldn't keep up with the work I had for it I bought the LS900 new. My machine guy dropped 'em off, showed me how they worked, and THATS all I know about lasers! I've learned how to make my lasers sing & dance, and I understand the generalities of their workings... I've torn 'em both apart (to some degree) and put 'em back together, etc... but measuring mA's, knowing a DC tube from an RF tube, and most other electronic science about these things is greek to me!

I build a lot of aluminum operator panels, and the quality of my work is why I keep getting more-- It won't do me much good to buy a laser that can mark 4 panels at a time instead of just one if the text & graphics end up looking like a caveman did it! Should I assume my Universal and French-made Gravograph have RF tubes? I have no idea, but the engraving quality on both is great IMO, although the big machine has a banding issue that drives me nuts, but that's another story...

Should I be able to get this Triumph laser with an RF tube? Is DC vs RF a tradeoff result of higher power?

Since joining this forum, I'm amazed at what I don't know! ;)

[Robert Silvers]

I see C02 as for cutting organic material - wood or acrylic, or engraving glass, stone, or tile.

A C02 can only mark painted or anodized aluminum. If you want high quality marks on aluminum, you are better off with YAG or Fiber. They are about $15,000 to $20,000 for a Chinese one.

C02 engraving is fuzzy if you get really close.

[Dave Sheldrake]

Lemme see Kev,

Leaving aside higher power lasers (1Kw +)

RF = Radio Frequency tubes, they use the same/similar gas as a DC tube but the beam is generated by an RF signal
DC = Direct Current tubes, they are excited (the beam is generated) by a very high voltage arc inside the tube (circa 20,000 to 45,000 volts)

DC tubes (in general) do not have the availability to have their number of pulses per inch varied, RF tubes do.

Your ULS and Gravo are "likely" RF tubes.

Different materials have different values at which they absorb radiation (the beam) a CO2 laser provides a beam of 10,600nm (in rough terms) a YAG and a Fiber laser generate beams in the 1064nm wavelength.

Aluminium for example is highly reflective to the 10,600nm wavelength but absorbs 1064nm wavelength very well. Therefore aluminium will require far far higher power to cut/mark if you use a CO2 laser compared to low power for a Fiber or YAG.

A 20 watt YAG/Fiber will outperform a 200 watt CO2 on aluminium because of this.

Wood absorbs radiation (the beam) in the 10,600nm wavelength very well, but does not in the 1064nm wavelength so the CO2 laser will outperform a YAG or a Fiber on wood.

Wavelength:

This controls the smallest possible size of your laser spot/dot.

A YAG or Fiber can in theory produce a dot 10x smaller than a CO2 making them very good for fine detail work (depending on the material type etc) as well as being able to mark directly on most metals.

Chinese YAG / Fiber Galvo markers start at around $10k and go upwards. (be aware they are pretty poor if you want to cut items though)

A triumph machine with an RF source is like fitting a Ferrari engine to a Skoda, you can do it but do you want to? you would end up with a $5k machine with a $10k laser in it if you wanted 100 watt or so.

My apologies if this comes over as overly simplistic but I'm not sure quite where your level of knowledge is of Lasers in general.

cheers

Dave

ps:Z series tubes have better internal mirrors and slightly higher peak powers but past that in real terms not much different. To be honest I prefer EFR tubes as they seem to be more stable.

[Joseph Belangia]

Hey Dave,Thanks for breaking that down for us. My wine-level was at the perfect spot, and I followed it through....pontificated...maybe had another sip, and then considered myself a bit smarter leaving the day than I came into it.

[Dan Hintz]

If you want high quality marks on aluminum, you are better off with YAG or Fiber.

I disagree. A large part of my business has been marking anodized parts, and I wouldn't do so well if my parts came out fuzzy. Yes, you can certainly get finer detail with a YAG/fiber, but most would be hard-pressed to know the difference unless they were looking for 2-pt fonts.

[Robert Silvers]

Well, both of us are correct. You can sell C02 marks to people and they will be happy with them - I have bought products that have C02 marks on aluminum, and while I wondered why they were soft, I didn't mind. If you show them next to a fiber mark, the fiber will be clearly better to just about anyone. So I guess it depends on what level of quality you are going for.

I would bet a lot that a $15,000 Chinese fiber laser will produce much higher quality marks on aluminum than a $20,000 Epilog C02 laser.

[Dan Hintz]

Here's one I did years back... it was not dialed in, but it's a reasonable sample.
272721

Now, feel free to pontificate on how much better a YAG/fiber will do compared to this, but those arguments have been bashed again and again here. If the above is not acceptable to most customers (this is an automotive engine part), then they'll pay the price for a more expensive fiber machine to do the work, simple as that.

[Kev Williams]

Hey, oversimplistic is fine by me! And I do understand (to a point) the basics of electronics, just never learned the nuances of my lasers- or lasers in general. It's nice to learn something about them!

OK then, since I can set the X-axis dots-per-inch on both my machines, I'll assume I have RF lasers...

Next-- regarding DC tubes aren't 'typically' able to vary their firing pulses per inch-- question, if the pulses can't change, then wouldn't the correct static measurement be pulses per second? And then wouldn't the laser head speed then be the deciding factor in actual pulses per inch? Meaning, the slower the head speed, the higher the dots per inch resolution...? And if so, then slower speeds should render better results? Yes, no?

Below is a couple of pics of another piece of anodized I just did, with the letter heights, down to .025" tall letters, and while the smaller letters do get fat and a bit fuzzy, they're still easily readable with even my old bi-focaled naked eyes! I wonder if Robert (or anyone else too?) would mind running a similar sample(s) and posting a photo of the results? I'm very curious about this now-- As much as I'm ready to break out my checkbook and get one of these, I'd really love to see some unbiased samples of some small text engraving! (sorry if I'm being a pain!)

[Dan Hintz]

Meaning, the slower the head speed, the higher the dots per inch resolution...? And if so, then slower speeds should render better results? Yes, no?

You have to keep in mind that each pulse of the laser (RF or DC) has a finite size... a circle of material will be bleached, vaporized, etc. For a 2" FL lens, that spot size is typically around 5 mils for a good beam (RF tubes), maybe 7-9 mils for a lesser quality beam (generally DC tubes). That sets the max resolution you can truly have. Overlapping those dots will give you a smoother edge, but in the end the resolution of the final image is relatively limited to the minimum dot size you can achieve. For a 5 mil dot, that's roughly 200dpi if the dots don't touch, at half overlap that's closer to 400dpi... but as you can see, the smallest feature you could hope to create would be 5 mils.

You can play tricks, so to speak, however... setting the print resolution to 1000dpi will allow you to print an 8 mil wide line (two dots almost completely overlapping), but you can still go no smaller than a 7 mil thick line. Keeping this in mind will help you set an appropriate print resolution, allowing you to trade speed for final image quality. For example, when printing to wood, I could print a decent image at 333dpi. Jumping up to 1000dpi doesn't really gain me any extra detail because the substrate itself is fairly low resolution... but it would gain me a deeper (or darker) engraving at the expense of more time.

[Dave Sheldrake]

Sit on your money for a bit longer Kev, quick decisions on lasers usually end up being bad ones ;)

DC tubes as mentioned above tend to use a PWM control (Pulse Width Modulation) if effect meaning you vary the length of the Pulse (laser on time)
RF tubes tend to use PRF (Pulse Repetition Frequency) in effect meaning you vary the number of pulse in a given time (distance when related to speed)

PWM = Length of pulse in a given time
PRF = Number of pulses in a given time

It is possible to vary the frequency of a DC tube but is a bad idea, the electronics / physics behind it is quite complex but it can lead to a far shorter lifetime on the tube if you do.They are designed to run within a small variation on frequency for 99% of Chinese tubes. Some western tubes like GSI Slc's can be varied but a 200 watt GSI Glass tube is just short of $25,000 for the tube alone compared to $3,500 for a 200 watt Chinese tube.

The 0.025" lettering you have posted is below the 1mm size a typical Chinese DC laser will produce, YAG and Fiber Chinese machines will go to 0.5mm but a DC Gantry (plotter type) will rarely give good results below 1mm x 1mm font sizes.

Be aware also China is very good at making some rather *generous* claims about what their machines will do, such as cutting 30mm acrylic with a 100 watt tube etc, yes 99% of what they say is true but rarely includes the caveats we all really need to know. 30mm acrylic WILL cut on a 100watt DC tube but at 0.1mm per second and the quality will be terrible.

Often the statements are true but the meaning behind them isn't.(you get given just enough information to come to the wrong conclusion)

Don't get me wrong I love Chinese lasers (and have/have had) quite a few of them, just don't be fooled into thinking they are everything that is sometimes claimed.

I have Chinese, Western, German and Japanese lasers and they all have their place but none of them are a "one size fits all" kind of solution.

cheers

Dave

[Kev Williams]

I assumed a fatter dot with a Chinese machine, but wasn't aware of why exactly until now! So should a assume a tighter dot result should be able to be had using 'tighter' 1.5" or so lens? I realize focus is more critical with a tighter lens but that shouldn't be an issue with flat aluminum panels. Realistically, if I can get crisp lettering down to .050" tall characters, that would be sufficient... :)

[Robert Silvers]

Kev - the spot size mostly has to do with the emitted beam diameter. You may want to find out the emitted beam diameter of any tube or unit that you are considering, because then you can calculate how small the size the spot may be. I am sure RECI will tell you their beam diameters if you email them.

Here is a spot size calculator:

http://www.buildlog.net/cnc_laser/laser_calcs.htm

And here is some info:

http://tinyurl.com/ksnvlch

http://www.parallax-tech.com/faq.htm

[Kev Williams]

Thanks for all the good info Robert, Dan and Dave, much appreciated! As I said in my previous post, if I can get basic lettering to look good down to .050", then I'm good to give it a shot. The price of the machine is about what I spend every 3 months on materials, so it's not a huge gamble for me. And hey, biz was so good this year I need a tax deduction! ;)

I have plenty of work I know the machine is definitely capable of doing nicely, and I have a new wood customer with jobs that require a high-power machine capable of engraving 8' long boards. The work it WILL do will free up the other 2 lasers at the very least. My utmost hope is the increased production the bigger laser (and the IS7000 I'm getting next week) will jog my biggest customer into sending me a few of the 6000+ jobs someone across the pond is doing for them.. Just a small piece of that pie will allow me to buy WHATEVER I need later.

[Dave Sheldrake]

Beam modes vary between tubes Rob, RECI are usually good but TEM01 - TEM08 isn't unusual. (the shape of the beam the tube produces)

Kev, yup shorter focal length = smaller spot but not always better spot quality. Focussing a big incident beam (the incoming beam from the tube) to a smaller spot also increases aberration (a straight beam going through a curved surface).

I'd probably look at going with an EFR ZX series 80 watt tube and a 38mm focal length lens.A Meniscus lens from II-VI InfraRed will give better quality without costing an arm and a leg (China tend to supply Plano - Convex lens's)

cheers

Dave

[Robert Silvers]

My attempts at cutting 1 inch acrylic.

Is there any way that I can improve this? The focus was a bit below the surface. I also tried surface focus, but I didn't like the taper.

So far I have not been able to get better edge quality by using lower power.

http://imageshack.com/a/img585/4711/25i7.jpg

[Scott Shepherd]

My attempts at cutting 1 inch acrylic.

Is there any way that I can improve this?


My educated guess would be "No". That's wayyyyyy too thick for that power laser with that lens setup. I have a 3/4" piece that looks awesome and it was cut on a 400W laser.

[Robert Silvers]

Can anyone explain why more power at a faster speed is better than less power at a slower speed?

If it is heat transfer causing distortion - I get it, except that yesterday I was told to turn down my power to get better cuts.

This test seems to show that more power is better.

Would a four inch lens make a big difference?

How long does it take to switch between lenses?

[Scott Shepherd]

Would a four inch lens make a big difference?

How long does it take to switch between lenses?

A 4" lens would do worse on that material, in my opinion. I can't cut thick acrylic without air and a 4" lens gets the air nozzle so far from the cut, you get serious fire issues and blistering of the acrylic. 1" is just exceeding the ability of your machine. I know you are just trying different things to learn, but honestly, even if you could get it to cut 1" thick, it would be so slow that you couldn't make any money doing it.

[Robert Silvers]

Laser engraver vs Brother MFC-8710DW laser printer:

http://imageshack.com/a/img823/6888/0qm3.jpg

http://imageshack.com/a/img405/4206/7nws.jpg

[Scott Shepherd]

Y'all stop cheating and use upper and lowercase letters in your tests! It's a much better test because it'll test how your laser handles ascenders, descenders and things like the dot on an "i".

Let's see the 3 point font with upper and lower case using L, p,g,l,i, and letters like that.

[Robert Silvers]

1 mm/sec is not all that slow to me for something that I may do once or twice and where it does the work by itself.

For real use I plan to be at 9mm or less thickness.

Tell me more about air. I am trying to hook up a real compressor as I am getting very little air, and do have fire.

I ordered part number


5225K713 (http://www.mcmaster.com/nav/enter.asp?partnum=5225K713)




from McMaster-Carr - and I think that will do it for me.

[Dave Sheldrake]

Can anyone explain why more power at a faster speed is better than less power at a slower speed?

It's not, Lasers are more stable in their output at lower powers, as soon as you get into the 90%+ range you can easily cause the mode of the beam to become unstable.


If it is heat transfer causing distortion - I get it, except that yesterday I was told to turn down my power to get better cuts.

Uh huh, quite true, what is happening in your samples is you are trying to butcher through material way too thick for that type of machine (power rating).Laser cutting generates gas, much of that gas is CO2, CO2 blocks IR radiation causing sporaddic power to be delivered to the workpiece. Lower power causes less heat to be generated in the material avoiding meltback and core melting,If I ever cut thick acrylic (above 12mm) it gets done on a 600watt. What you are seeing in your samples is a tube that is too weak to cut 1 inch acrylic, the results may suggest more power is better but when you are at the limit of your available power something is going to give.


Would a four inch lens make a big difference?

On that thickness it would get worse, you would lose power density so it would be akin to trying to cut through a brick with a kitchen knife.


How long does it take to switch between lenses?

About 5 minutes.


This test seems to show that more power is better.

It is, but only when it's real power not the difference between 50 watts and 100 watts, try more power as in 800 to 1,000 watts to really see a difference.

cheers

Dave

[Dave Sheldrake]

Tell me more about air. I am trying to hook up a real compressor as I am getting very little air, and do have fire

More air will help if it is properly delivered, a 10mm nozzle standoff with a 5mm exit hole will cause the laser to striate the cut (making it look like a gear wheel), in the case of acrylic more air isn't always the best answer, you need volume but at lower pressure to stop pre-setting of the vaporised acrylic before the cut goes through.

cheers

Dave

[Robert Silvers]

First I need my milliamperes meter to see if I am even at real max power. I do seem to have Gaussian distribution at my current indicated max power setting.

I don't follow how less power means the work gets less hot. You have to slow down the cutting speed, so that gives much more time for heat to build up.

And again, I just saw a recommendation for 600+ watts, so that is suggesting more power is good, not less.

I am going to describe it as "Use your highest power where you have Tem00, which may be less than your max power so do tests to find out what your highest clean power setting is."

[Dave Sheldrake]

I don't follow how less power means the work gets less hot. You have to slow down the cutting speed, so that gives much more time for heat to build up.

Bigger power = beam mode issues, beam mode issues means heat distribution will be wider, you are trying to vaporise something and not induce carbon formation.More induced heat means a wider effect.


I do seem to have Gaussian distribution at my current indicated max power setting.

Based on? you have a DWC?


"Use your highest power where you have Tem00, which may be less than your max power so do tests to find out what your highest clean power setting is."

Cheapo Chinese tubes don't get TEM00


I just saw a recommendation for 600+ watts, so that is suggesting more power is good

Not it's not, it's suggesting a machine that has a 600 watt source is likely to be far higher quality than a cheap Chinese one, tubes of that power level in DC versions are usually GSI or similar, totally different ball game. The laser heads are different, the drives are different, the optics are different, the focussing methods are different, the air assist / gas assist is different, the pulse rates are different, the wavelengths are more defined + a bucket load of other differences.


First I need my milliamperes meter to see if I am even at real max power.

Due to manufacturing tollerance in Chinese DC tubes a meter won't tell you if you are at max power, for that you need an Ophir setup and a DWC. All a meter will tell you is if your PSU is pumping the correct current into the tube, it won't tell you if the voltage is right or even close. That's long before you get into polarisation modes and aberration issues.

cheers

Dave

[Robert Silvers]

Yes, I may or may not achieve the rated max power of my tube, but all I have control over is adjusting the power supply for current, so I can at least make sure that when set to 100%, it is not above or below 26ma of current - which is what RECI suggests to do.

So based on what I just learned, we can boil it down to energy density, for which watts are one part of that, but so is spot size and if your beam has an ideal distribution or not. And spot size is a function of original beam diameter, focal length, and wavelength. And then on top of that is pulses per second, for which glass tubes have limited control over, and RF is much more flexible for being optimal in that regard. And there is no market for cheap 600 watt units, so when people speak of higher power units, it is implied that it will also have better optics.

Here is my beam at 98% power (as indicated on the software) - how good or bad is this? Or do you need a side photo close to a clear edge? I don't have that because I did it on an unpolished edge, but I can cut it out.

http://imageshack.com/a/img19/4016/v63w.jpg

[Dave Sheldrake]

Impossible to say Rob, you need a DWC to look at beam profiles instead of the effect of a beam on an unknown quantity (material)

There are a massive number of variables once the beam gets fired at a mirror or a lens (even when just passing through space) it gets very much into the realms of Particle Physics which while interesting can get a "glazed over" look from most people. Even at it most basist level, a simple thing like particles in the air between the incident point and contact point on the materials. If you have dust or smoke or vapour or gas in the air for example and that dust is above the wavelength size you get absorption or reflection, below wavelength size you get scattering.
That's just the effects of dust, well before the many other variables get taken into consideration.

Most of it can be summed up with "does my machine, Chinese or Western do what I want it to do"

If yes, the physics rarely matter
If no, then it gets complicated.

cheers

Dave

[Robert Silvers]

My beam diameter is 8.5mm at the location where I measured it. It may be 8mm at the muzzle.

The calculated spot size is about 0.0034 but I seem to be more like 0.008 in the real world. Those US lasers must look better from being closer to the 0.0034. If so, they would have about as much energy density from a 20 watt as I have from a 100!

So maybe I was wrong to compare my price to a 100 watt US machine. I probably could have compared it to a 40 watt.

[Dave Sheldrake]

A western 30 watt will do what an eastern 60 watt will do on average.

It's not quite so viable to compare RF to DC (budget types) as they are different animals and vary a lot in quality. That said a GSI Slc DC tube will kick any of the lower end RF's (sub 150 watt) out of the game park. It should do though, it's nearly $26,000. Chinese RF units are coming on fast, not quite "there" yet but doing well.

If you want a better , more defined spot from the Z4 get a meniscus lens from II-VI InfraRed, China tend to fit Plano-Convex's (usually the wrong way up as well) as they are cheaper but they area cheaper for a reason. Figure on a II-VI lens costing about 3x as much as an eastern version.

cheers

Dave

[Robert Silvers]

Has anyone changed to that lens and measured their spot size before and after? If it can raise my energy density a lot, I may want it. I don't think it need it for practical purposes, but I enjoy doing the comparison. What will it cost me?

[Robert Silvers]

http://www.parallax-tech.com/faq.htm#cut

"If we remove the perfect assumption (the lens is not perfect and the laser is not perfect) then you would be doing amazingly good if your lens and laser are good enough to give you a spot size of 100 micron diameter ( 0.1 mm ). You will be doing excellent if you get 200 micron ( 0.2 mm ) and very good if you get 300 micron ( 0.3 mm )."

When I first saw that with my beam diameter and focal length the best spot size that I could get was 0.08mm, and I had an actual spot size of about 0.2mm, and I knew that I was only achieving 1/6 of the potential energy density - it seemed like I should upgrade the lens.

But then I read on, and this FAQ says that 0.2mm is an "excellent" spot size and 0.1mm is "amazingly good."

"Therefore, if you get a CO2 laser and an ordinary (affordable) ZnSe lens, you should be happy to get a spot size diameter anywhere from 250 to 500 micron = 0.25 to 0.5 mm diameter. From your spot diameter you can calculate the spot area and from there you can calculate your beam intensity at any power setting."

It says I should be happy, but I need to find out what I can expect for a spot size reduction with a ZeSe meniscus lens.

Here is how to figure that out:

http://www.iiviinfrared.com/resources/spherical_aberration.html

A Meniscus lens will have a spot size of about 1.5x smaller than Plano-convex.

That will change my power density from 3094 to 6938 watts per square mm, which is like keeping the same lens but bumping my power to 225 watts.

But then I saw someone else say that they would only increase cutting speed by 5%, which confuses me.

And I see them for sale ranging from $35 to $500, with no evidence that one is better than the other.

[Dave Sheldrake]

But then I saw someone else say that they would only increase cutting speed by 5%, which confuses me.

welcome to the exponential function. Power density is a measurement of power / area in 2 axis. Laser cutting is a product of power/area/depth (3 axis)

cheers

Dave

[Rodne Gold]

Most of it can be summed up with "does my machine, Chinese or Western do what I want it to do"

If yes, the physics rarely matter
If no, then it gets complicated.

cheers

Dave
+100000
These things are just tools ..either they do what you want or not.
The only difference really is affordability ... some folk can afford a $5k entry fee and live with compromises , if you cant afford $20k for a "better" machine any compromises are academic.

[Dan Hintz]

]
When I first saw that with my beam diameter and focal length the best spot size that I could get was 0.08mm, and I had an actual spot size of about 0.2mm, and I knew that I was only achieving 1/6 of the potential energy density - it seemed like I should upgrade the lens.

But then I read on, and this FAQ says that 0.2mm is an "excellent" spot size and 0.1mm is "amazingly good."

"[/COLOR]Therefore, if you get a CO2 laser and an ordinary (affordable) ZnSe lens, you should be happy to get a spot size diameter anywhere from 250 to 500 micron = 0.25 to 0.5 mm diameter. From your spot diameter you can calculate the spot area and from there you can calculate your beam intensity at any power setting."

It says I should be happy, but I need to find out what I can expect for a spot size reduction with a ZeSe meniscus lens.

Don't get too worked up about the Parallax site... their overall description is correct, but they also give rules of thumb rather than hardcore numbers. Western lasers are typically at 5 mil spot size for 2" lenses, 3 mil for 1.5", and approaching 1 mil for the setups which include beam collimators (like ULS's HPDFO).



Dave, you'll have to verify me on this one as it's been a long time since I ran the numbers... didn't the meniscus lens have a bigger issue with aberration near the lens edge compared to a plano-convex (given the same basic production quality), which meant you needed a larger diameter meniscus to avoid the edges? Someone do a search here, I vaguely recall writing up a minor thesis on the subject a few years back.

[Dave Sheldrake]

Dave, you'll have to verify me on this one as it's been a long time since I ran the numbers... didn't the meniscus lens have a bigger issue with aberration near the lens edge compared to a plano-convex (given the same basic production quality), which meant you needed a larger diameter meniscus to avoid the edges? Someone do a search here, I vaguely recall writing up a minor thesis on the subject a few years back.

Spot on Dan :) Plano suffer from the Zernike aberrations more so than Meniscus but to avoid spherical abbs the lens needs to be bigger :)

cheers

Dave

[Robert Silvers]

welcome to the exponential function. Power density is a measurement of power / area in 2 axis. Laser cutting is a product of power/area/depth (3 axis)

cheers

Dave

Still the relationship between the two lenses would be the same with various depth materials. So for a 3mm material, the 2.25x difference in power density would still be 2.25x for a 9mm thick material.

Has anyone bought one of those $30-$50 Chinese Meniscus lenses that say they are made in the USA? For this wavelength, it would seem easier to make a perfect shaped lens than visible light since you have 10x looser tolerance for perfection.

[Dave Sheldrake]

So for a 3mm material, the 2.25x difference in power density would still be 2.25x for a 9mm thick material.

Power density is an area function, cutting power is a volume function.


it would seem easier to make a perfect shaped lens than visible light since you have 10x looser tolerance for perfection.

?? Visible light runs 400 or so nm to 700 or so nm,


lenses that say they are made in the USA

Made in the USA means nothing, it depends on the manufacturer. II-VI, Zeiss, RMI are all great "Bobs backroom lens shop LLC" doesn't confide anything.

cheers

Dave

[Robert Silvers]

Power density is an area function, cutting power is a volume function.



?? Visible light runs 400 or so nm to 700 or so nm,



Made in the USA means nothing, it depends on the manufacturer. II-VI, Zeiss, RMI are all great "Bobs backroom lens shop LLC" doesn't confide anything.

cheers

Dave

Going from a spot size X to a spot-size X/1.5 is the same as going from a 100 watt to a 225 watt laser. Do you disagree?

Ok, so going from an 10600 to 700 is a 15x difference, so an IR lens is 15x less critical for lens imperfections because the wavelength is 15x longer.

BTW, the took apart my lens unit. It is 20mm in diameter, and was in upside down. The convex shape was pointing down. I changed it to point up.

[Scott Shepherd]

Going from a spot size X to a spot-size X/1.5 is the same as going from a 100 watt to a 225 watt laser. Do you disagree?




I'm not a physics student, but from know what I know about lasers, I'd say that's a very false calculation there. If you put a 2.0" lens in and cut 1/2" thick acrylic with 100P and 2S, putting a 1.5" lens in, it's NOT going to cut at 100P and 4S, or 50P and 2S. It doesn't work that way at all with the laser I have been exposed to.

I've used a 2.0 lens and a 4.0 lens over the years and the 4.0 lens doesn't produce 50% of the power of the 2.0 by any means.

[Dave Sheldrake]

Do you disagree?

Yes, you are basing the calculation on power density in relation to better cutting ability,

You have a finite power in the incident beam, at the infinite level of the material surface you have X watts per SqMM, that is an area function, once the beam transgresses the material surface you are working in 3 dimensions not 2.Not only is the radiation being absorbed by the flat 2 dimensional surface it is also expanding due to the curve in the 3rd dimension as well hence being lost in progressively higher rates as the beam diverges.


o an IR lens is 15x less critical for lens imperfections because the wavelength is 15x longer.

Not quite sure how you got that idea?


doesn't work that way at all with the laser I have been exposed to.

Quite right Scott, Rob is getting confused between an area factor and a volume factor. If the beam at focus was a cylindrical shape into infinity then it may have some merit but it's a (hopefully) Gaussian curve with a finite limit on the amount of energy being focussed.

Rob, Lasers follow the inverse square law and the exponential function when cutting, unless of course you don't factor in the finite power levels being emitted. If they didn't you could build a star wars death star for 50 bucks out of a laser pointer with a G2 focus lens attached to it.

cheers

Dave

[Scott Shepherd]

Quite right Scott, Rob is getting confused between an area factor and a volume factor. If the beam at focus was a cylindrical shape into infinity then it may have some merit but it's a (hopefully) Gaussian curve with a finite limit on the amount of energy being focussed.

I just know it doesn't work :D

[Robert Silvers]

I removed the lens and cleaned it, and flipped it over so that the convex part now points up.

I have auto focus working, but I am perturbed that I need to make new height gauges. I think in the future I will be able to take this apart and put it back where I don't lose focus, but flipping the lens over may have made that impossible this one time.

While it was apart, I replaced the 3mm Phillips screws with 3mm socket head cap screws.

My beam is almost 0.002" smaller now.

I believe this upside down lens was increasing spherical aberration and making my 100 watt laser behave like a 65 watter. This may explain why my cutting speed was slower than the charts.

[Robert Silvers]

I want to take this step by step, because there may be some steps that you agree with.

Step A:

Reference http://www.iiviinfrared.com/resources/spherical_aberration.html

Spot size due to spherical aberration: = (k * (D * D * D)) / (F * F)

F = 50.8mm
D = 8mm
K = 0.0187 for Meniscus and 0.0286 for Plano-Convex.

So approximate possible spot size is 0.094mm for Meniscus and 0.144mm for Plano-convex.

Agree or disagree?

Step B:

If you divide these, then we can see that a Meniscus lens would be expected to reduce the spot size by a factor of 1.528.

Agree or disagree?

Step C:

http://www.buildlog.net/cnc_laser/laser_calcs.htm

Power density of 100 watt laser with perfect beam and 0.094mm spot size is ~14348 watts/mm^2.
Power density of 100 watt laser with perfect beam and 0.144mm spot size is ~6140 watts/mm^2.

Agree or disagree?

Step D:

If you have a 0.144mm spot size, and you want a power density of about 14348 watts/mm^2, you need a laser with about 234 watts.

Agree or disagree?

Step E:

Therefore, a 100 watt C02 laser with a Meniscus lens can perform the same as a 234 watt laser with a Plano-convex lens.

[Robert Silvers]

I've used a 2.0 lens and a 4.0 lens over the years and the 4.0 lens doesn't produce 50% of the power of the 2.0 by any means.

The comparison has to be done on lenses of the same focal length. The 4 inch has more depth of field, so the spot does not get larger as quickly throughout the depth of the material, so the effects cancel each other out.

[Scott Shepherd]

The comparison has to be done on lenses of the same focal length. The 4 inch has more depth of field, so the spot does not get larger as quickly throughout the depth of the material, so the effects cancel each other out.

Where do you suggest getting lens with the same focal length and different spot sizes from? On all the mainstream lasers, the spot size is relative to the focal length, so there's no way to separate the two.

[Robert Silvers]

Where do you suggest getting lens with the same focal length and different spot sizes from? On all the mainstream lasers, the spot size is relative to the focal length, so there's no way to separate the two.

By one lens having more spherical aberration than the other.

[Rodne Gold]

Surely if it was so easy to get "extra" 2.5x the power with merely a lens shape change , all laser mnfgrs would supply their lasers with such a lens.

[Robert Silvers]

Surely if it was so easy to get "extra" 2.5x the power with merely a lens shape change , all laser mnfgrs would supply their lasers with such a lens.

I am convinced that it is a fact that reducing spot size by 1.5x diameter will raise energy density by 2.25x, and make a 100 watt laser perform like a 225.

What is unknown to me is if going from my stock Plano-convex lens to a good Meniscus lens will reduce the spot size by 1.5x as the II-VI website claims, or something less.

As to why the cheap Chinese machines don't do this? There is a 10x difference in prices of the lenses, and you can market 200 watts and raise the price by a lot, but you cannot easily market "better lens equal to lots of free watts" and raise the price of your machine in a highly competitive market.

[Dave Sheldrake]

A, B, C, D all good (I haven't done the figures but I'll trust you have)


Step E:

Therefore, a 100 watt C02 laser with a Meniscus lens can perform the same as a 234 watt laser with a Plano-convex lens.

Problem, again you are considering only 2 axis, X & Y and missing the finite power available (ergo Z)

Surface powers are calculable quite easily, BUT once you move away from it's focal point the divergence of the Gaussian beam drops your power density very quickly, more so with shorter focal lengths, add in to that much of the radiation is absorbed by the material inducing heat (Lasers beams themselves have no temperature as they have no effective mass, temperature is a product of molecular excitation, no molecules = no measurable heat) (Caveat: close enough but I'm not about to write up 15 pages on particle physics at 8 o'clock on a Sunday evening)
The more divergence there is in the beams curve the more surface area the beam is in contact with.(the *cone* gets bigger) The arbitrary figure for DOF is 1.4x spot diameter in either direction BUT that is NOT a parallel beam, it is simply an arbitrary figure) so even 0.1mm below the focal point and even though it is within the DOF the power density has changed.

Power density of lasers is a theoretical thought experiment based on IF the beam was 1mm^2 at the same ratio of incident power the density would be X, due to there being a finite limit on the amount of incident power to do the reverse test you would need to expand the beam and have the same power density @ 10mm^2 100mm^2 1000mm^2 etc etc

In effect although the thought experiment suggests @ 1mm^2 a 0.144mm spot size is ~6140 watts/mm^2. you don't have 6140 watts of available energy hence if you did expand the beam you density would drop.

What you are missing is:

A laser beam is working in 3 axis not 2
A laser source has an upper limit on the energy it can supply (you cannot magically get more power just because the spot size is bigger)
Spot sizes are finite irrespective of DOF calculations
Laser beams are Gaussian curves not tapers ,cones or straight lines after they hit the focal lens.
The math only works if you calculate finite power and reducing spot sizes, not if you increase spot sizes.

cheers

Dave

[Robert Silvers]

I may have found a problem with all of this:

http://www.iiviinfrared.com/resources/determine_spot_size.html

This chart shows that spherical aberration does not play a role except for beams over about 15mm. I am confused as I thought the lens diameter would play a role, but they have no variable for it.

[Robert Silvers]

Surface powers are calculable quite easily, BUT once you move away from it's focal point the divergence of the Gaussian beam drops your power density very quickly

You can still calculate the spot size for any given depth, and for any given focal length, which is fixed in my example, the spot sizes will increase at the same rate.



What you are missing is:

A laser beam is working in 3 axis not 2
A laser source has an upper limit on the energy it can supply (you cannot magically get more power just because the spot size is bigger)
Spot sizes are finite irrespective of DOF calculations
Laser beams are Gaussian curves not tapers ,cones or straight lines after they hit the focal lens.
The math only works if you calculate finite power and reducing spot sizes, not if you increase spot sizes.

Take two lenses. One with a 0.2mm spot size, and another with a 0.1mm spot size. As you said, both will only be perfectly in focus and have that spot size at one depth of the material, and then they will diverge in a cone. But 10mm deep into the material, and so out of focus, the larger spot will still be twice as larger as the smaller spot. Do you agree with that? And if so, I think that means that what I said works out.

If we want to look for a reason why the real world does not work out like this simple math, I bet it has to do with this:

http://www.iiviinfrared.com/resources/determine_spot_size.html

[Dave Sheldrake]

and you can market 200 watts and raise the price by a lot

Not unless somebody has disproved the main principle of the first law of thermodynamics in the last 20 minutes. "The total energy of a closed system remains the same"

cheers

Dave

[Robert Silvers]

Not unless somebody has disproved the main principle of the first law of thermodynamics in the last 20 minutes. "The total energy of a closed system remains the same"

cheers

Dave

I am not sure what you mean. 200 watt lasers sell for much more than 100 watt lasers, but you can't add a Meniscus lens to a 100 watt laser and charge as much as if you sold them a 200 watt laser with a Plano-convex lens.

[Dave Sheldrake]

If we want to look for a reason why the real world does not work out like this simple math, I bet it has to do with this:

It's more basic than that. You do NOT have an infinite power source. Spot size power density only work in reducing spot sizes NOT increasing.
Basic secondary school education these days teaches that Entropy ALWAYS increases.


And if so, I think that means that what I said works out.

Noooo it doesn't! you don't have an infinite power source!

Light a nice size fire in your backyard,

Get a 15mm bore hosepipe and spray the fire with 1 litre of water @ a flow rate of 500 litres per hour.
Get a 15mm bore hosepipe and spray the fire with 500 litres of water @ a flow rate of 500 litres per hour.

Both have the same flow rate, both are water, both have the same exit hole in the pipe, both have the same emergent pressure.

One doesn't put the fire out!

cheers

Dave

[Robert Silvers]

Spot size power density only work in reducing spot sizes NOT increasing.
Basic secondary school education these days teaches that Entropy ALWAYS increases.
The distance before the focal point for which the beam is contracting to 2mm diameter is going to have about the same energy density as the distance after the focal point where the beam has expanded back to 2mm in diameter, except for minor environmental loses.

If you disagree, then tell me how much different they will be.

[Robert Silvers]

I ran the full equation here:

http://www.iiviinfrared.com/resources/determine_spot_size.html

While the 1.5x spot size reduction seems to be true for a beam width in the 25-30mm range, with an 8mm beam width, the spot size difference is only about 1.02 times different! This is because the diffraction limit dwarfs the spherical aberration factor.

This means that if I change my lens from Plano-Convex to Meniscus, I can expect my 100 watt laser to perform like a a 104.4 watt laser that has a Planto-Convex lens.

So this website which claimed up to a 5% difference now makes sense:

http://www.ophiropt.com/co2-lasers-optics/focusing-lens/knowledge-center/tutorial/lens-design

So in summary, I will probably buy new lenses as Meniscus, but I am not going to buy one of the same focal length I current have as the performance difference is minor.

[Dave Sheldrake]

except for minor environmental loses.

That *minor* environmental loss is going to be the absorption rate of the material, the amount of energy converted into heat, the amount of energy available to overcome reflectance, refractance, Zernike aberration, mode change, divergence, backscatter, co2 absorption, particulate scatter or reflectance.

Without knowing the exact atomic structure of the material the beam is directed at it's impossible to calculate as you are missing one variable. If it were not any more than minor losses then nobody would ever need bigger lasers, I could sell my 7.5kW Mitsu and buy an 80 watt ULS.

A laser beam doesn't hold it's shape once it comes into contact with a solid.

cheers

Dave

[Dave Sheldrake]

This means that if I change my lens from Plano-Convex to Meniscus,

A Chinese Plano to a II-VI Meniscus is a world of difference. Quality control and lens radius is far superior on a quality lens Vs Chinese cheap stuff.


I can expect my 100 watt laser to perform like a a 104.4 watt laser that has a Planto-Convex lens.

No it won't because you don't HAVE 104 watts!

cheers

Dave

[Robert Silvers]

That *minor* environmental loss is going to be the absorption rate of the material

But that would be the same between the two examples, so it is not a variable that we need to consider for comparison purposes.

I think you were trying to reconcile how I could be so far off the reality and came up with various potential reasons, but in the end, it was due to the fact that it was improper for me to only consider the differences in minimum spot size due to spherical aberration when the much larger diffraction limitations also needed to be considered.

[Robert Silvers]

No it won't because you don't HAVE 104 watts!

I am simply saying that a better lens can make my 100 watt laser perform as if it were 104 watts.


A Chinese Plano to a II-VI Meniscus is a world of difference. Quality control and lens radius is far superior on a quality lens Vs Chinese cheap stuff.

I am already down to 0.006" spot size with my included lens, so it seems close to as good as Piano-Convex gets as far as spot size goes due to diffraction limits. Now maybe it has poor coating, I am not sure.

I am not too worried about the radius - as the long wavelength makes it easy to get that within diffraction limits.

Most likely if I spent ~$500 on a II-IV, it will show a spot size reduction close to my calculation.

[Dave Sheldrake]

fact that it was improper for me to only consider the differences in minimum spot size due to spherical aberration when the much larger diffraction limitations also needed to be considered.

Forget all the aberrations, particle physics and II-VI web stuff, it's down to power...the amount of input energy. This is the limiting factor for any laser.


But that would be the same between the two examples, so it is not a variable that we need to consider for comparison purposes.

It's exactly what needs to be considered, if we use 10 watts of the available energy to cut the first 1mm depth

The 100 watt has 90 watts remaining
The 200 watt has 190 watts remaining

In a straight linear comparison at 10mm depth the 100 watt has no more power available(power/energy, a potential to do work), the 200 watt has 100 watts remaining.

It's REALLY simple Laser Physics. There are no free gains ,if there were we would all be running our cars on over unity converters.

cheers

Dave

[Dan Hintz]

No it won't because you don't HAVE 104 watts!

Let me try it a different way, Dave.



Rob, your tube puts out 100W of power... period. If you were able to capture all of the energy exiting the end of the tube, it would measure 100W. You can form that 100W of energy into a really fine dot or a really fat beam, but it is [y]still[/u] 100W.

What makes a laser cut is the ability to raise the density of that power above a certain threshold. The smaller the dot you focus it into, the higher the power density. Too low of a power density and you will simply warm the substrate up, but not cut through.

So, when you talk of using different lenses to create a finer point, you are not increasing the power of the laser (which is 100W), you are increasing the power density. Laser's are sold as the tube output power (the 100W), not by power density, so your desire to sell a 100W laser as a 200W+ laser because of a lens change does not follow. It's akin to saying a car that normally goes 100mph is now a 150mph car because you put smaller wheels on it and the speedo shows 150mph... the engine is still the same size (to be fair, this is not a perfect analogy, but you should get the idea).

[Robert Silvers]

Dan,

Yes, I know. I agree with what you say, and don't believe I said anything that contradicts it.

[Robert Silvers]

A good lens will make your 100 watt perform as well as a 130 with a poor lens. Yay!!

cheers

Dave

I am not comparing good to poor so much as Plano-convex vs Meniscus. I am saying that for an 8mm beam diameter, Meniscus has a 4.4% advantage in power density potential.

[Robert Silvers]

your desire to sell a 100W laser as a 200W+ laser because of a lens change does not follow.

That is not what I meant, and not what I said.

I was asked if it was so easy to raise power density with just a lens change, then why wouldn't every laser come with the Meniscus lens? I said that the lens costs 10x more, and it is not as marketable and hence they could not get as much increased selling price as selling them a higher-wattage laser.

[Robert Silvers]

Let's reboot.

My goal was seeing how much better a Meniscus lens would be over Plano-convex for spot size, assuming both lenses were the same focal length and "quality."

Answer is: The spot size would be smaller by a factor of about 0.978. This will change power density by about 1.044.

That is all I am saying.

Yes, II-VI brand lenses may be better in other ways, such as radius, and surface quality.

[Dan Hintz]

That is not what I meant, and not what I said.

Evidence to the contrary, it seems, as shown below.


...and you can market 200 watts and raise the price by a lot, but you cannot easily market "better lens equal to lots of free watts" and raise the price of your machine in a highly competitive market.

You suggested a lens change would allow Chinese manufacturers to raise their prices because they could market the machine as higher wattage. As I said, this doesn't follow. The manufacturers could sell the machines with a meniscus, a plano-convex, or no lens whatsoever, but it would have zero effect on the tube wattage. They could still only list the machine as whatever wattage the tube puts out.





You can't keep saying one thing and then come back later and claim something else. We're trying to help you, but if you keep biting the hands that feed you we're going to stop offering bread.

[Robert Silvers]

You suggested a lens change would allow Chinese manufacturers to raise their prices because they could market the machine as higher wattage.

Reading back I can see how it was ambiguous in how I said it, but I never meant that they could market a 100 watt laser as a 200 watt laser after changing the lens. What I meant is that they could market a 200 watt laser as a 200 watt laser and that was marketable as a way to gain power density, but a fancier lens was not as marketable as a way to gain power density.


We're trying to help you, but if you keep biting the hands that feed you we're going to stop offering bread.
You are a very helpful person. For this specific question I was only trying to calculate the potential gain from a Meniscus lens, and while I did not know how to do that when I asked the question, I have since learned how to do that and have posted links to the equations and an example with my specific setup.

[Robert Silvers]

Somewhere I posted that cutting 5mm acrylic was 95% power and 10mm/sec - and that was slower than the charts. I think someone responded that it did seem slow.

Since I flipped my lens over and retuned it - now the same acrylic piece at 95% power will cut in the 15-20mm/sec range. I think things are good now.

[Dave Sheldrake]

I was only trying to calculate the potential gain from a Meniscus lens

It's not the gains in delivered power that matter Rob, it's the gain in beam profile / quality. II-VI info while very valuable in a lab is little use in real world situations where there are other variables to consider (read: when dealing with cheapo laser machines)

Some basic issues:

The lens will be sat on a mount that is unlikely to hold it centrally
The lens barrel is in a tube made to a price and not a standard
The mirrors will be good / average quality with a reflective index around 95 - 97%
Your tube can only dream of TEM00
The power supply won't be that stable on output
The tube water temperature will vary (even if only by 2 degrees or so)
The lens barrel will get warm in use
The mirrors will get warm in use
The table is highly unlikely to be flat / parallel with the gantry rail
The tubes gas mix will contain quite a bit of Helium (to cover for the high pump energy causing heating)
The tube output will fluctuate far more than an RF unit
Your air assist is likely orders of magnitude farther away from the work than it should be
The air assist will be side input causing all sort of vortexing issues with the air output
The exit hole in the cone will be too big
The nozzle standoff will be too much
Your alignment will be off (even stabilised lab lasers drift 100Mrad per day)

All this before we even get to the physics of the optical train. The equations II-VI kindly provide are VERY useful if your working with high end lasers or lab equipment but alone when used on Cheap Chinese machines they are just guides rather than solid testable factors.

If however when a client calls I just give them the results of the physics equations they will be less than happy when the results don't match the numbers (that to be honest, is if they even understand them, Zernike calculations aren't basic maths)

For a normal Chinese laser?

Good quality meniscus lens (don't need to spend $1000's a simple $120 lens will do it)
Good quality Gold Si or Moly Mirrors (molly if you forget to clean things)
Keep the belts and slides clean (and greased with lithium grease in the case of slides)
Clean BOTH sides of the final lens (most people forget the top as it's enclosed)
Keep the mirrors clean (dirty mirrors no matter how good reflect about as well as a brick)
Clean the output coupler of the tube (they go bang if you don't)
Keep the crud cleaned out from below the work area (you should see how fast an extractor will accelerate a fire)
Watch for bubbles in the right hand end of the tube (even the pump impeller under water all the time can cause bubbles,have a look at the outboard on a boat for an example)

Above all, if it's not broken don't fix it or it soon will be.

A Chinese laser is never going to be a ULS or Trotech, it's not meant to be, if it does what you want it to be happy, if it doesn't you bought the wrong machine.

One of my machines is a test bed, it's a 180 watt HX1290, if it gets broken I'll learn from it and not do the same thing to my shop machines.

cheers

Dave

[Dave Sheldrake]

I think someone responded that it did seem slow.

Yup, I did.

Be aware that tubes settle after a honeymoon period so you may find that drops to 14 to 16mm a second after about a month or so.

cheers

Dave

[Robert Silvers]

I asked Triumph about Meniscus lenses, and they said "The focus lens of your laser TR-9060 is high quality Meniscus lens with 2 inch focus length."

They said that additional 2 and 2.5 inch Meniscus lenses are $60 each.

It did seem that the flat side had a little curve to it.

[Dan Hintz]

It did seem that the flat side had a little curve to it.

Lay a straightedge across it... should be easy to see if there's any curve to it.

[Dave Sheldrake]

The focus lens of your laser TR-9060 is high quality Meniscus lens with 2 inch focus length

Sadly a contradiction by Triumph, if spares are 60 bucks then they aren't high quality.

A meniscus has quite a pronounced curve on the concave side, that should be easy to see without any kind of optical aid. I have a box of Chinese Plano's here and they do have a "bow" in the *flat* side but are quite a way from true meniscus.

cheers

Dave

ps: You work for AAC Rob? small world ;) seems like a lifetime ago I used to work with firearms.....

[Robert Silvers]

Yes.

It seems easy to make an IR lens diffraction limited. Then it comes down to transmission and reflection losses, which I know nothing about. I have nice optics on other things, including an Astro Physics telescope, a Takahasi telescope, a Sinar view camera will all Zeiss lenses, two Leica cameras, a Leica spotting scope, Leica and Swarovski binoculars, a Nikon microscope, and lots of Canon L series lenses.

So I am all about quality optics. That being said, I have seen no evidence that there are lenses that will improve my laser output given my current laser tube.

[Dave Sheldrake]

A poor Chinese lens on test is considerably worse than a good western such as an RMI or suchlike.

Chinese quality control is suspect to say the least. They are good (better than I could make for 50 bucks) but still not in the same ball park as II-VI or RMI etc. A good addition would be a DWC or better to get some real results, manufacturer claims are one thing, actual real world is something else.

272980
272981

This is the sort of equipment that makes a difference between having a good lens that pumps 100 watts and a bad lens that pumps 100 watts, the beam propagation characteristics are critical if you want results. Power meters, Amp meters and suchlike give overall snapshots of basic readouts but no detail to work with. Even using quality kit like the Ophir stuff won't tell you anything much apart from Raw power, a trash lens and a good lens will read the same on the CRX4:000 power meter and that's a $5,000 piece of kit.
Without knowing the propagation ratio and how close you are to a single mode M^2 of TEM00 the rest of the numbers are just so much theory and not much else. Once you have the data then waist location, spot size minimum, power density, shape, uniformity and divergence can be calculated, it also permits aligning the delivery optics and most importantly aligning the source to the lens system.

Once you have that data the rest becomes clear when looking for differences between good lens's and bad ones.

cheers

Dave

[Robert Silvers]

My lens was made in the USA.

[Rodne Gold]

Theory, albeit very interesting and informative , and practice are 2 different things

I use el cheapo chinese lenses in my "mainstream" machines , they do the job VERY well , they are ZnSE lenses.
I recently bought 10 lenses for $300 , LESS than the $350 GCC agents wanted for just 1 !!!!
Undoubtedly the better lenses DO work slightly better especially for cutting , but when running 8 lasers and having staff that are less than meticulous when cleaning lenses (despite training) , it is an economic decision as we treat lenses as "consumables"
In general laser engraving , the detail you get from these lenses is as good as any customer wants or needs , small spot sizes are a double edged sword too , especially when doing fills or large area solid engraving.

[Dave Sheldrake]

Exactly Rod :)

Wayyy too many variables to worry about optics in a production environment. Gaining $75 worth of production on a lens that costs $120 is pointless.

Rob is looking for perfection in machines not designed to provide it, the optical properties of a lens in Zeiss Bino's isn't a good comparison as the rest of the device is made to Zeiss standards, sticking Zeiss lens's in wallmart binos won't have much benefit.

The optical physics is great(technically interesting if you like physics) if it means anything and in the day to day running of a laser it means nothing.

cheers

Dave

[Pierre Brassard]

Hello Robert! I bought a Triumph laser cutter 50w via ebay two years ago. I'm having the same problem you encountered last year: I switched from Windows XP to Windows 7 64 bits, and Phcad won't work on the new computer. I tried contacting Triumph people through email (two different addresses) to get a compatible version, but they've been ignoring me so far! You said you had greater luck reaching them, and got a download link for a compatible version.
If you have any suggestion that could help me resolve this issue, I'd be very grateful!
Cheers,
Pierre

[Robert Silvers]

https://app.box.com/s/k39ff6z6sjed0yrqis04

[Kev Williams]

They have a version 7.01 now, cool. I've GOT to give it a tryout. I've been using the PHSOFT 4.47 version. I have PHCAD 5.76 but I've never been able to use it more than 3 minutes before it crashes or scrambles up all my saved parameter settings.

Thanks for the link! :)

[Kev Williams]

Seems to work okay, has a lot more features...

Now, if someone could just steer me to a plain english set of instructions or information that explains what the bazillion different parameters and their settings mean... :)

[Scott Shepherd]

Kev, it's really simple.

Step 1 - You find doger setting crawl 14 under advanced tabular mode change cutting power speed device stepping motor.

Hope that clears it up for you :)

[Kev Williams]

ha ha, you funny very man! ;)

but seriously-- here's a screenshot of one of the parameters dialogs and their settings...

http://www.engraver1.com/erase2/phparam.jpg

Now, from "control panel parameters" down, I have those pretty much figured out, although I'm not sure what "panel acceleraton" is, or why my panel needs to accelerate? ;) But pretty much everything in the "crafts parameters" section is a ??

Like, "acceleration mode", there's a choice between S-type and T-type-- ?? What's the difference?

From there down, I have no clue...

If there's ONE problem I have with this machine, it's the (how to put this?) power difference between short areas and long areas being lasered, and this mostly applies to text, such as T's, where the top is long, and the shaft is short. The long expanses get substantially more burn than the short areas. This is the root of my Cermark problems on stainless issues; if I get the short areas to burn correctly, the long areas overcook, and if I get the long area's to burn correctly, the short area's don't get enough heat and the Cermark won't stick--

I understand much of this issue likely stems from the glass laser itself, but I 'm wondering if any of these settings I don't understand might help to compensate? I'm just an unedjukated dummy who'd love to understand what all (some) of this all means! :)