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Laser cutting machine

Discussion in 'Design and technology' started by Johntudor7, Nov 22, 2017.

  1. Johntudor7

    Johntudor7 New commenter

    Has anyone purchased a low end laser machine, if so, how does it perform; what are its limitations. I do understand you get what you pay for but when finances are limited, options are also limited.
     
  2. elder_cat

    elder_cat Lead commenter

    Don't have on myself, but there are various YouTube videos demonstrating the typical cheapish Chinese-built lasers sold on eBay. From the vids they seem to be OK if you're looking to do stuff like cutting thinner acrylics etc. The main bugbear seems to be the limitations of the software controlling them, so I suppose it depends on what you intend to use them for.
     
  3. Scubadt

    Scubadt New commenter

    We had a laserpro one. It did the job for cutting and engraving acrylic and mdf, but the software it uses is pretty clunky. Since have another brand that acts exactly as if it's a printer, straight from 2D Design. No farting around with 2 or 3 bits of software or file formats.
    If you don't mind a bit of fiddling around the laserpro was fine, but it did drain a bit of time setting everything up.
     
  4. Johntudor7

    Johntudor7 New commenter

    Thanks for your replies. What make and model did you buy second time round Scubdadt, we will be using 2D Design?
     
  5. Scubadt

    Scubadt New commenter

    It's a GCC Mercury III, I think. It was in the region of £10k I'm sure, but it's been worth every penny. The original one was an HPC one, not laserpro, which may be part of the GCC machines full name.
     
  6. Duke of York

    Duke of York Star commenter

    I used to sell laser cutters and got to know everything there is to know about the brand I was selling and its immediate competitors in the high end market and where they differ from the cheap ones. I'll try to explain how, although they are all laser cutters there are such fundamental differences between the cheap and expensive ones, it would be like saying that cheese and ham are identical since they are both categorised as food.

    The most fundamental difference between the cheap and the high-end laser cutters is the type of laser tube they have.

    Low-end lasers use glass laser tubes, which suffer from short lifespans, typically six months. When they fail, they have to be replaced with a new tube. The gas in the tube is prone to leaching through the seals, so even if you keep a spare tube in stock, there is no guarantee it will work when you need to use it. Being glass, they are prone to getting damaged in transit. They require very high voltages in the KV range to stimulate the laser. Components working in this voltage range are prone to early failure. Finally, laser tubes generate a fair amount of heat, so glass laser tubes are water cooled. In an ideal world, the water will pass through a chiller, however the very cheap lasers will be supplied with a bucket in which a submersible pump similar to that used in a fish tank. The water is pumped up a rubber tube into a glass coil inside the laser tube then into another rubber tube to return it to the bucket. It's a technology that hasn't changed since lasers first became available in the early 60s.

    High-end laser cutters use RF stimulated laser tubes. These were originally designed for military use and have constantly evolved. They are robust, precision devices made from metal and give a long life, typically around ten years. They are initially expensive, but when they reach the end of their lives, they are re-charged at relatively low cost. They are air-cooled by powerful fans so there's no need for the messing around with water and the inherent problems it has.

    To appreciate the next part, you need to understand a little about how lasers work. LASER stands for light amplification by stimulated emission of radiation. If you raise the level of energy in an electron, it reaches a point where it becomes unstable and needs to release the excess energy to return to its natural state. It releases the excess energy in the form of a photon - a particle of light. The photon in turn, raises the energy in another electron so it produces another photon, which has identical frequency and phase as the original photon etc etc etc, until you have a coherent beam of intense light. It takes time to get the process going; and although this may only be a matter of milliseconds, there are very good reasons why you want this to be as fast as possible.

    RF stimulation generates a significantly faster response from the laser than is possible with glass tubes. It allows the laser to be sent as a series of pulses, whereas with glass tubes, you get a continuous laser.

    Now lets consider what happens to the material when the laser heats it. Each material reacts differently to being heated. Plastics might shrink away from the heat, wood will char, paper and card will burn and so on. By varying the pulse frequency to suit the material, it's possible to minimise the unwanted effects on the material. RF lasers can when correctly used, cut paper and textiles with no noticeable side effects. Glass lasers can't avoid these.

    Next we come to the user interface. The majority of cheap laser cutters use a generic user interface. It's overly complex to understand what each parameter that can be changed does; and since it was developed in China, the instructions on how to use it are difficult to comprehend unless you're Chinese and read the manual written for the Chinese market. Although I understood the technology well enough, it took me the best part of half a day to comprehend how to get to grips with the the basics of the software. You have to go through many more processes of sending your design to the machine before you can press the start button than you need to with the expensive machines.

    Manufacturers of the expensive machines invest a lot of money in improving their machine designs and also a lot in improving the user interface. I left the market around five years ago, so I can't advise what the latest machines offer, but long before I left, the software had evolved to the extent that the user had the option of merely selecting the material being processed and entering its thickness, then all the settings were automatically calculated. Everything was taken care of.

    You drew your design and printed it. In the printer properties you selected the material, entered its thickness and pressed the start button. The machine then automatically adjusted the table to the correct focus height, ran the job and you got a perfect result. So simple to use and ideal for school use.

    Now let's consider some H&S factors.

    Lasers carry some significant hazards. Most of you will be aware of the hazard of being exposed to the laser, but what about the risk of fire or of the risk on inhaling toxic fumes?

    High end laser cutters have interlocked access doors that prevent the laser being used when the are open. Cheap lasers don't.

    High end lasers have heat detectors within the enclosure that shut the laser off and sound an alarm if the material catches fire.

    The companies that sell high-end lasers will be aware, if they are any good, of the necessity of adequate fume extraction and what needs to be done with the fume.

    Cheap lasers invariably come with an extraction fan that pumps the fume outside the building to pollute the atmosphere and become a health risk to anyone passing by the vent. Expensive laser cutters will be sold by a reputable dealer with an extraction and filtration system that safely contains the fumes.

    I hope it's possible to see here that there's a vast difference in what you get for your money. I doubt I will ever be in the market for a laser cutter myself; and I'm glad I've been able to move on from flogging them.

    The history behind how and why lasers cutters became part of a D&T dept's wish list is an interesting story in its own right and if there's anyone who who doesn't know it and is interested, they can ask me.

    My career in flogging laser cutters lasted around fifteen years before I decided to retire from it and my views about why they were purchased and the benefits they brought my various customers are mixed. Some business customers who understood how they could benefit from them became extremely prosperous. Others didn't; and I wish they'd never convinced themselves it was what they needed.

    Schools, and in particular UK ones have been the fastest growing market for laser cutters, but I've yet to find many that genuinely comprehended their true potential or had much idea how to access it. The most frustrating part of that part of my working career was the inability of teachers being able to get the time out of their schedules to be properly trained..

    I can't tell you how many times teachers had to disappear from the training at crucial points to cover lessons, oversee playground duty or manage kids boarding buses. Nor can I tell you how many times I took calls from from frustrated teachers who had damaged their machines because they'd missed that crucial part of their training.

    I found it ludicrous that in the first instance teachers were spending years to prepare bids to purchase a machine, yet couldn't be allowed the time to understand what it was they were actually bidding for or how it differed from another machine, exactly what they intended to use it for and how when it was delivered were deprived of the time to learn how to use it properly.

    Ironically, I sold the second laser cutter any school ever bought. The first one went to a school who bought a very cheap one to explore its potential and wrote an article about what they'd done with it that inspired the teacher who bought the second laser to investigate the technology further.

    He had come from industry before he became a D&T teacher. He visited the school with the first laser, was impressed with it's potential, but entirely unimpressed with its quality. He researched the market, eventually found me and after he bought his machine and he and his team received two days uninterrupted training in how to get the best from it.

    I marveled at the results they achieved and in an article the HoD wrote, he said the training was the best inset he'd ever had. I need to put this in the context that back in the year 2,000, I had no idea of why a school might find any use for a laser cutter. Knowing what I now know os school laser use, I could have given him the best inset any teacher on the planet has ever received, but those were very early days.

    I'm more than happy to pass on my experiences in an entirely impartial way, particularly now I'm out of the business.

    I won't name who the rogues in the industry are, but if anyone wants to know what to look for to avoid them and the questions to ask, I'm more than happy to advise.
     
    gardenclanger and Scubadt like this.
  7. Johntudor7

    Johntudor7 New commenter

     
  8. Johntudor7

    Johntudor7 New commenter

    Thank you very much for your reply, I think you have clarified my fears and thoughts. The problem I have, the same as most other departments, is lack of funding. We will never be able to afford the machine we want, we have been given about £4000. Is there a second hand market?
     
  9. Scubadt

    Scubadt New commenter

    Duke of York...great reply. Very interesting.

    What, in your mind, is the true potential of laser cutters in schools?

    Ours is used almost every day, though mainly for personalizing projects (and homers!) We're trying to work together projects which take a cad sketch and end in a laser cut scale model, but as you say, time constraints are severely limiting.
     
  10. Duke of York

    Duke of York Star commenter

    They occasionally come up for sale, but usually get snapped up quickly. In the fifteen years I was in the business, we were asked on seven occasions if we wanted to buy used machines. We bought them, serviced them and sold them on with recharged tubes, so the customer wouldn't get any nasty surprises. I have seen some on ebuy from time to time and sometimes it's possible to pick up an ex-demo machine from a dealer for a good price.

    As I indicated in my post, the high-end manufacturers are constantly looking for ways to improve their products, or have needed to change them for reasons such as the EU RoHS legislation, which forced them to use different components.

    When they introduce a new range, the old range gets discontinued, so the demonstration machines for the old range get sold off cheaply. Among the reasons that manufacturers change their ranges are improvements in laser and software design, intended to increase productivity, because the high-end machines are primarily designed for industrial use.

    Something that isn't always understood by teachers is what industry use the machines for. A significant part of it is for engraving rather than cutting; and for that, the higher the engraving speed, coupled with the higher the engraving quality are frequently what drives the innovations.

    With the best will in the world to look after the demo machines, taking them to trade shows etc, inevitably they eventually get scratched, so a dealer might choose to replace a demo machine. Manufacturers sell dealers demo machines at a discount, so they can display the machines in the best light. If you can live with a scratch, you might pick one up at a good price.

    I hinted earlier that the history behind how and why lasers cutters became part of a D&T dept's wish list is an interesting story and is worthy of consideration for making a case for purchasing a laser cutter or deciding to spend your money on something else.

    If you go back in time, some bright spark decided that schools needed to teach CAD/CAM and introduced it as a curriculum requirement. The trouble was, as visionary as this decision was about what the nation needed schools to teach, the cheapest machinery to do it with at the time was going to set a school back forty grand and have a massive classroom footprint. Companies that had previously supplied schools saw this as an opportunity to develop ranges of Mickey Mouse CNC machines, which were too complicated for children to program. Teachers too, since they could never get enough time away from their teaching duties to learn how to use the technology properly.

    These machines were ridiculously under-powered, took an eternity to machine anything, since they could only drive 2mm cutters and were frequently left to run a file overnight in the hope it would be finished by the morning. If this wasn't daft enough, they relied on double-sided sticky tape to hold the workpiece in place. It rarely did, so at some point in the night, the cutter became worn, applied too much pressure to the workpiece, so the fixing tape gave way and broke the tool as it flied off the table.

    Every school I visited to install a laser cutter had an example of such a machine gathering dust in a corner.

    Teachers had been tearing their hair out trying to get this rubbish to work, so when the potential laser cutters had to overcome all the frustrations was noticed and the word spread, they quickly became the must have thing. The early advocates of the technology had some great ideas on how to use laser cutters effectively, but I'm sorry to say that as the market grew, it attracted cowboy suppliers and widespread misinformation between teachers on what to buy.

    Something I read on this forum frequently, for example when teachers were looking for advice on what to buy, was advice to buy the largest and most powerful machine you can afford.

    That is probably the most stupid advice anyone could follow.

    You only need a large machine if you intend to cut large parts. I've yet to visit a school that has the budget to sustain the purchasing of large pieces of material and those that go down this route inevitably find that a kid cuts something out of the centre of a large sheet, rendering it hard work to use the rest of it.

    Laser power...

    What this means needs to be understood. There isn't a laser manufacture on the planet who has been able to change the laws of physics, so we need to get our heads around why some claim greater cutting performance over their competitors. In the early days of selling lasers to schools, one of my competitors claimed that their 25W laser could cut through 20mm thick acrylic. They weren't lying, but they were misleading in their advertising. They could just as easily have claimed that a 10mW laser could do the same and still not be lying.

    To get your heads round this, try to imagine how long it would take to cycle a thousand miles, to drive it in a low-power car, versus a high-power one for to fly it in either a small prop plane or a jet. Each one is capable of doing that journey, but how long will each option take; and are their any downsides those options have?

    'll tell you from the outset that nobody in their right mind would attempt to cut 20mm acrylic with a 25W laser and I'll tell you three good reasons why not.

    The speed at which a laser can penetrate a material is directly related to how much energy is applied to the material and how dense it is, along with how long the material is exposed to the laser. In theory, a laser of any power can cut through any thickness of material if you have enough time.

    In other words, a job that takes a minute with a 1,000W laser will take ten minutes with a 100W one and forty minutes with a 25W one.

    The longer you expose a material to heat, the higher the chance there is of you damaging it beyond repair, the higher the chance that the fumes will ignite and set fire to the material and in the case of acrylic, which is highly inflammable and difficult to extinguish, once lit will probably result in the loss of the machine or an expensive repair. It can also lead to loss of life since acrylic fires are very intense.

    And yet, this nonsense has been propagated by the people who flog this company's machines on the basis that the claimed machine's performance isn't a lie.

    I wonder how many schools have the budget to afford 20mm thick acrylic?

    Most of all, I wonder how many schools have a clear plan of what they intend to do with their laser cutters. I'll let you into a secret. My D&T education in the 60s consisted of woodwork, metalwork and technical drawing. It taught me the skills for how to make stuff well enough to gain a career in technology that was both interesting and financially rewarding. I can say without a shadow of doubt that it's highly unlikely this will have been possible if my school technology education had revolved around using a laser cutter to tick a box that our education had covered CAD/CAM, but all I'd done was make a model of something from cardboard, because that was the only material the budget could run to and the pathetic ideas suggested by those who design the curriculum include toy designs.

    What are these people on?

    A year or so ago I suggested it was easily possible to inspire kids with technology by looking at medical applications for it.

    It's well within the capacity of a sixteen year old kid to understand what an ECG is all about or how to understand how to record it. Equally, they could appreciate what a spirometer does and how to make one. These were once rocket science, but they're not now. As hard as you try with a laser cutter, you won't be doing anything to improve a child's education or improving the success of the nation in general. You're only ticking a box that the kid was taught CAD/CAM in a pointless way.
     
    gardenclanger likes this.

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