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Thread: Cutting 1mm sterling silver sheets.

  1. #16
    The video is of a CO2 laser with oxygen assist judging by the look of the cuttig head, not the fiber they list. I also second what Dave says about power. I have been recommended a minimum of 700W fiber to cut silver. I just checked the quote and it does list nitrogen as assist gas for silver.
    G. Weike LG900N 100W RECI RDWorks V8
    Leiming LM2513FL 1kW Raycus fiber laser cutter

  2. #17
    Quote Originally Posted by Jacob John View Post
    I was questioning him stating that it's a CO2 because their link states that it's a fiber. Definitely not questioning his experience.
    Dave has been very vocal about Chinese lasers using Oxygen assist. He will correct me, for certain, but they seem to skip some very important safety measures, which makes them a bomb waiting to happen. I recall him posting photos of a laser accident (if I remember correctly) and it wiped out a brick building and killed people. Just because the Chinese can do it and show a video of it working, doesn't mean it's safe. I'd tread very carefully into such a machine.

    I'm sure Dave can expand on the dangers.
    Lasers : Trotec Speedy 300 75W, Trotec Speedy 300 80W, Galvo Fiber Laser 20W
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    Real name Steve but that name was taken on the forum. Used Middle name. Call me Steve or Scott, doesn't matter.

  3. #18
    Thanks for the kind words Scotty, I'm still very much learning as well.

    CO2's wavelength see's silver like a mirror, once the Silver starts to melt it forms a highly reflective melt pool, that pool is in effect a liquid mirror.So scatter becomes a problem right away. Added to this the 10,640 wavelength of the CO2 beam isn't absorbed by the material very well at all (under 5% of the beam is actually *taken in* by the silver so for every 100 watts you fire at it, only around 5 watts are making it through.

    Oxy assisted CO2's aren't really cutting by use of laser beam, what happens is the tiny melt pool forms on the steel and the oxygen introduction causes a fast exothermic reaction oxidising the metal, that's what's actually doing the cutting.

    Fibre with it's 1,064 wavelength is not reflected by silver at any where near the magnitude that CO2 is so more of the *beam* is getting through, this allows the beam to break the molecular bonds of the metal allowing it to be cut (a photochemical action and not a photothermal , bandgaps etc) the Nitrogen is used to prevent oxidation of the surrounding area and the melt pool oxidising as well as a *pusher* to force the *liquid* metal through and out of the way
    I don't know much about precious metals however if sterling contains copper then you have a second two fold problem,

    Copper makes VERY good mirrors, so much so industrial CO2's use it for mirrors so that's going to be a problem, secondly copper is an exceptional conductor of heat, as you are trying to gain heat in the cut the copper will be doing it's best to conduct it away from the cut so efficiency drops again.

    Cut quality with low powered CO2's + Oxygen isn't great, it works and is accurate but the underside has very much the same finish as a plasma cutter with dross and scag being a bit of a problem, it will rarely if ever produce finished quality parts that don't require a bit more work like de-scag or dross removal (tumble polishing)
    Oxycuts are also always discoloured unlike nitrogen that cuts with a clean shiny edge

    If I was looking to cut silver @ 1mm I'd be aiming at 1kw Fibre and better still more likely 2 - 2.5kw to get decent speed and efficiency
    No longer an active member so messages may not be replied to.

  4. #19
    Just saw Scotty's comment about safety

    Very much so, untested and uncertified Chinese metal cutters that use Oxygen are bombs

    Oxygen is not flammable but it will make things that are normally not flammable into very flammable things. The gas lines on Chinese Oxy's tend to be Chinese quality, they aren't tested to UK standards and in the wrong circumstances can become "fuel" rather efficiently. They don't have tested "Intrinsic electrical safety" on lasers that use oxygen not only are all the supply routes of the oxygen strictly tested also the escape route of unused oxygen is controlled, you don't want a machine bed filling with unused oxygen gas if there is any signs of mineral oil or spontaneous combustion can become a big problem very quickly.

    A self fuelling oxygen fire is as bad as it gets, it burns HOT ...VERY and the fire fighting methods of putting it out are very different...as Scotty mentioned, I did a consultancy job in India on an oxygen based explosion in a laser...it literally looked like a JDAM hit the building, one of the fatalities was still there when I arrived, they were busy trying to wash him off the wall with a fire hose

    If you did want an oxy supported laser you can get them from the US and the UK that have been modified to meet the strict safety standards required for these kind of machines, in general though they are not the kind of machine I would counsel for a new laser user, they are simply too dangerous if you make a mistake and the results of those mistakes are very often fatal
    No longer an active member so messages may not be replied to.

  5. #20
    The easiest way I can put it?

    Apollo One, that was an oxygen fuelled fire
    No longer an active member so messages may not be replied to.

  6. #21
    To bump my own thread, I'm looking at this machine, but it comes with a hefty pricetag.

    https://www.laserstar.net/products/l...utting-system/

    Anyone know of something similar and less expensive? Gantry fiber, compact desktop if possible. They state using an air assist instead of oxygen/nitrogen is possible. I'm really not comfortable using oxygen considering Dave's comments.

  7. #22
    Forgot to add, I looked at waterjets, which are awesome, but I'm worried about both the cost of consumables (garnet), maintenance, and kerf considering I want intricate designs. Plus, any idea on cutting speeds with a 30,000psi system? I'd love to hear some waterjet opinions in addition to the above posts on a desktop fiber.

  8. #23
    That LaserStar machine, for the hefty price (I'm guessing north of 45?) would have to be kept pretty busy to pay for itself and still leave a little left over for the operator! And for that money, would an autofocusing stepper driven table be too much to ask?
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  9. #24
    Think nearly 2/3 more.

    So now I'm considering:

    - Waterjet
    - Plasma
    - Kern CO2 cutter - And man I love their machines but I'm afraid of the risk of using Oxygen to cut. My machines are in my garage, and I'm afraid of fire or worse.

    Any thoughts? It needs to cut intricate designs so a waterjet, I'm not sure can cut to the kerf for some pieces though maybe a desktop microjet exists somewhere.
    Trotec Speedy 300 - 80 watt
    Synrad 30 Watt - CO2 Galvo
    LaserStar 3804 - 50 watt fiber - SPI Source
    Tykma Minilase - 20 watt fiber - SPI Source - (MOPA)
    CorelDraw X7

  10. #25
    Yes, small water jet machines exist, about $20k and will do up to 12" x 12". Made by Omax, who make larger industrial sized machines

    https://protomax.com/?utm_source=eas...SAAEgJL__D_BwE
    Brian Lamb
    Lamb Tool Works, Custom tools for woodworkers
    Equipment: Felder KF700 and AD741, Milltronics CNC Mill, Universal Laser X-600

  11. #26
    a little browsing found me this webpage - https://waterjets.org/archive/gettin...d-tool-offset/

    -they note it's old material but contained some possibly helpful info, an excerpt:
    Kerf” is a machining term that refers to the material removed during cutting... For example, if you cut a board with a saw, part of the board is turned into sawdust. If you put the two pieces of the board back together, you would find that they are slightly shorter than they were before, because some of that material (about the width of the saw blade) had been removed during cutting. The same effect applies with a waterjet machine: part of the material is removed during cutting. Of course, with a waterjet, the amount of material removed is much less than with a saw blade.

    Typically, the waterjet kerf will be about 0.020″ to 0.060″ (0.5 mm to 1.5 mm), depending on the nozzle and the horsepower of the pump. There are some specialty nozzles that have a very small kerf on the low end of this range and are useful for cutting jewelry where the material is expensive and fine detail is required. Most systems have kerf widths ranging from 0.030″ to 0.040″ (0.76 mm to 1.0 mm).
    A waterjet won't blow your home to bits, and it seems you might be able to find some nozzles that may work..
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  12. #27
    Thanks Brian and Kev! Omax is who I'm actually getting to run some test cuts for me early next week. They tell me that the kerf is .03" (.76mm).

    You think that small enough for intricate designs? They're confident that it will be.

  13. #28
    I forgot to add, the next question will be how much Garnet will I consume when cutting these pieces? Since that's a consumable, it will obviously add to the cost of producing a piece, but is it minimal enough to where I won't have to worry about it as far as pricing is concerned.

  14. #29
    I think .030" kerf, which amounts to a .015" corner radius is going to be plenty acceptable. I also suspect that with the thin material you want to cut, that might be able to be customized down even smaller. As for the consumption of the garnet, not sure that's going to be a big cost, first, it's usually not that expensive (at least not in blasting media) and from the pictures of the Omax unit, they appear to have an abrasive cup that isn't very large looking. I'm sure they can do a test cut and give you a breakdown of operating costs, garnet, electricity, does it use normal water or de-ionized? All of that should be something the sale man can get you info on.
    Brian Lamb
    Lamb Tool Works, Custom tools for woodworkers
    Equipment: Felder KF700 and AD741, Milltronics CNC Mill, Universal Laser X-600

  15. #30
    Quote Originally Posted by Brian Lamb View Post
    I think .030" kerf, which amounts to a .015" corner radius is going to be plenty acceptable. I also suspect that with the thin material you want to cut, that might be able to be customized down even smaller. As for the consumption of the garnet, not sure that's going to be a big cost, first, it's usually not that expensive (at least not in blasting media) and from the pictures of the Omax unit, they appear to have an abrasive cup that isn't very large looking. I'm sure they can do a test cut and give you a breakdown of operating costs, garnet, electricity, does it use normal water or de-ionized? All of that should be something the sale man can get you info on.

    Thanks Man! I'm getting more optimistic about this being a solution. I love my lasers, but for cutting, well, it just isn't cutting it. I wish there was a way to calculate the length of my pieces in EZCad because these waterjets have a speed in inches per minute. I could probably ballpark the cut time if I had that info, though it seems to cut a lot faster than my 50 watt. A small piece of copper on my 50 watt is about 12-18 minutes depending on size. That same piece in sterling is about 8 minutes. I think the same piece would be about a minute on the waterjet, maybe less.
    Trotec Speedy 300 - 80 watt
    Synrad 30 Watt - CO2 Galvo
    LaserStar 3804 - 50 watt fiber - SPI Source
    Tykma Minilase - 20 watt fiber - SPI Source - (MOPA)
    CorelDraw X7

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