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Tech supplies\glass tube laser cutters, recommendations?

Discussion in 'Design and technology' started by henryrolls, Jan 8, 2019.

  1. henryrolls

    henryrolls New commenter

    It's that sad time when our trusty 10 year old Gravograph LS900's laser is failing, the lens is cracked and the X movement occasionally misses steps. Gone too are those happy days of decent funding, but we have been told that there is 'some' money in the pot for a new one.
    I'm still waiting for a quotation from Gravograph for a like-for-like, as well as a complete overhaul, but I suspect (unlike a lot of technology) a new one won't have come down in price much and it may not be cost effective to replace so much on an ailing machine like ours, so we might have to settle for an inferior machine.

    So I'm compiling a list of cheaper proposals for our finance director. I spoke a very helpful salesman from Technology supplies, and have 3 machine prices ranging from £9000+vat for an X252 80w Glass tubed machine (smaller bed size but eqivalent to a 40W metal tubed one, our LS900 was 30w) to £12470+vat for the Mercury III (Metal tubed but only 25W and smaller bed size).

    I've also seen Tilgear do a Berghmann 60w machine with a bigger 600x900 bed for £8000+vat (I have seen it over a grand and a half cheaper on YPO but not sure about the extra fume extraction Tilgear mention.

    From what the salesman has told me, glass tubed machines do have shorter lifespan, but at around a grand to replace the tubes they are still cheaper to run than the several grand it costs when the metal tubes go (as with our LS900). He did say that etching on the metal tubed machines is more precise.

    Does anyone have any unbiased experience of both glass and metal tubed machines, and may be able to offer advice or recommendation of any machine?
     
  2. Duke of York

    Duke of York Star commenter

    I spent some fifteen odd years in the laser cutter industry and can suggest reasons why your machine is losing steps, why your lens got cracked and why it makes no sense to buy a machine with glass laser tubes.

    It takes a while to explain, but I'm happy to do so when it's not as late as it is now. If you're interested, PM me. I'd be surprised if your machine needs to be replaced on the information you've given or you'd be better off with a cheap replacement.

    Your machine just sounds like it needs a bit of TLC to return it to it's original state.
     
  3. BW12345

    BW12345 Star commenter

    Am using an ebay/Chinese variety of laser cutter. Cost new <£2k. The tube (60W ) "wore out" so we replaced it with an 80, as the psu was adequate (£220). Once aligned - (not difficult, it just takes some thought and care), it's doing well. Also gave it an ammeter £5 and a quieter fan £90. We'd previously put a proper chiller on it (and an interlock on the lid !!)
    I'd be interested to know a common reason for "losing steps" Duke -?? Ours isn't doing that. Yet.
     
  4. Duke of York

    Duke of York Star commenter

    It isn't really losing steps in the sense that the pulses to the motor are disappearing, it's more that the motor isn't able to use them.

    Stepper motors don't have a lot of torque, so if the motion system gets dirty the motor will sometimes appear to stall.

    Remember that laser fume can be dirty and sticky. A fair amount of fume ends up coating the belts, bearings and idlers. It will even find its way into the motor itself. If your extraction system isn't efficient at removong the fume and if you don't keep the machine clean, over time, the build up of crud becomes too much for the motor to overcome as intended.

    In practice, it's rare for a machine to be used over its entire working area, but does most of its work on a small part of it, increasing the exposure to fume on part of the belt and part of the track. When engraving at high speed, the motor may have the inertia to carry the carriage over a dirty patch, but not at the speed the controller is expecting.

    Stepper motors do not give feedback on how far they have travelled. They rely on the fact that x number of steps means y distance of travel. If the controller is sending the steps, but the motion system is sluggish in places and not travelling the expected distance, it appears as though some steps got lost.
     
  5. TimHall82

    TimHall82 New commenter

    Hi, I work for a company that designs and builds laser cutting equipment in the UK (Kent Lasers). Stepper motors themselves are usually very reliable devices, it is usually the electronic drives that fail before the motor (the part that amplifies the step and direction signals) this could be due to a failing driver output, or power supply (not enough current/voltage to adequately control the motor) This can easily be checked with a voltmeter.

    Fume extraction is also very important, as dust and contaminants from cutting can get into bearings, which then forms an abrasive "grease" that wears out linear carriages ect... I would steer-clear of any Chinese equipment, especially the ones with a bucket of water for cooling, I have seen some dangerous Chinese machines on my servicing duties, including no safety interlocks and exposed electronics - even when purchased from UK distributors.

    Glass tube lasers are not bad, however, and will happily meet the needs of education environments if designed and set up correctly. Their longevity can also reach many years, again if implemented correctly.

    Kent Lasers do offer free servicing for schools in the South East, so maybe its worth contacting them, even if they can get you up-and-running again for a few months, maybe this will be enough to get you by until funding is available?

    Their machines will also be more powerful (and have larger cutting areas) by comparison to other equipment

    I hope that helps?
     

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