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Thread: Used laser engraver addition

  1. #1
    Join Date
    Feb 2006
    Location
    Beavercreek, OH
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    476

    Red face Used laser engraver addition

    Finally brought home a laser engraver. No its not one of those nice brand spanking new Epilogs or even a Rabbit or a Trotec. Its a 5 year old Hurricane Hugo 60 watt machine that they were unable to get the laser to fire. After getting it home I found a few of the problems.

    1. The 6" ducting hole was reduced to 3 or 4 inches which would explain why the inside of the machine looks like they were burning the wood or running the laser to high.
    2. Extremely dirty inside.
    3. For some reason the laser high power lead from the laser power supply to the laser was cut in 2 and twisted together. That one by itself scares me.

    The only saving grace is a "0" hour 60 watt tube from lightsource.
    The machine has a tremendous "z" and it did include the rotary attachment.

    It will need a thorough cleaning before any real troubleshooting can start and maybe a new high power lead if I can't install a new end.

  2. #2
    Good luck on that project. Keep us posted.

    I went to Fairborn High School and played a lot of games against Beavercreek.
    Mike Null

    St. Louis Laser, Inc.

    Trotec Speedy 300, 80 watt
    Gravograph IS400
    Woodworking shop CLTT and Laser Sublimation
    Dye Sublimation
    CorelDraw X5, X7

  3. #3
    FWIW, I reduced the 6" hole in my Triumph to 4" because the smaller hole speeds up the air flow, which puts the actual moving air closer to the table, and the smoke... Smoke evacuates faster. So the smaller exhaust on your machine may have been an attempt to cure the smoke residue problem rather than being the cause of it-
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  4. #4
    Join Date
    Feb 2006
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    Beavercreek, OH
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    At this time I intend to stick with a 6" duct. My initial plans are to use an old 7" roof vent. I stopped by the local electronics dude and we were able to piece together the parts to make a resistor to test the laser. Oddly enough he didn't have a 50K ohm resister in his stash so we had to make one up.

  5. #5
    Join Date
    Feb 2006
    Location
    Beavercreek, OH
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    476
    Yesterday while digging into the machine and cleaning, lots of cleaning, I found the red Cathode wire spliced within maybe 5-10" of the laser tube. The connection was held together with a simple orange run of the mill wire nut. The other splice was just twisted together with no protection at all. I am looking at replacing the wire if possible and at the minimum taking it down to one splice. My thoughts on a splice would be the wires straight and meshed together with no points, soldered, heat shrink-ed, silicone rtv allowed to cure then several more layers of heat shrink. Does that sound like the correct way? I want to do this right since there are 30K volts going down in.

  6. #6
    Join Date
    Sep 2009
    Location
    Medina Ohio
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    You may not be able to solder the wire to the tube most just twist and seal it there. you could damage the tube with to much heat.

  7. #7
    Kev, I can visualize that the air flowing in the tube would be faster at the entry point, but surely you don't think it would evacuate air at a higher volume.
    Chinese 6040 by NiceCut. Originally 60 Watt upgraded to 150 Watt.....I thought I had pretty much every problem in the book of laser cutting. It turns out that there is a set of books.

  8. #8
    The increase in air speed creates more vacuum, which is more efficient at removing smoke than sheer air volume.

    Think vacuum cleaners- the end of the small attachments hose will suck up MUCH more dirt from deeper within carpet fibers than the same air flow spread across a wide carpet cleaning head, simply because the deep dirt is drawn into the faster moving airflow. Getting a wide head to draw up an equal amount of dirt would require a much higher volume of airflow, which is why they use brushrolls

    --Also, the amount of air volume lost to a 4" hose from a 6" hose is minimal.

    More realistic reference- I have a plastic blast gate on a 4" solid-flex vent pipe near my fiber. If I close the gate somewhat, the vent draws MUCH more smoke than it does full open...
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  9. #9
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    Sep 2009
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    Quote Originally Posted by Kev Williams View Post
    The increase in air speed creates more vacuum, which is more efficient at removing smoke than sheer air volume.

    Think vacuum cleaners- the end of the small attachments hose will suck up MUCH more dirt from deeper within carpet fibers than the same air flow spread across a wide carpet cleaning head, simply because the deep dirt is drawn into the faster moving airflow. Getting a wide head to draw up an equal amount of dirt would require a much higher volume of airflow, which is why they use brushrolls

    --Also, the amount of air volume lost to a 4" hose from a 6" hose is minimal.

    More realistic reference- I have a plastic blast gate on a 4" solid-flex vent pipe near my fiber. If I close the gate somewhat, the vent draws MUCH more smoke than it does full open...
    Moving air is all you are doing a bigger hose has less restriction and moves more air just like a hose if you have the same amount of water flowing through a large and small hose it takes more pressure to push it through the small hose to get the same amount out

  10. #10
    Quote Originally Posted by Kev Williams View Post
    --Also, the amount of air volume lost to a 4" hose from a 6" hose is minimal.
    That's HEAVILY dependent on the fan curves for your blower. A 6" duct has more than double the cross sectional area of a 4" duct. Your fan may be able to compensate somewhat with more backpressure, but it's absolutely not true across the board.

  11. #11
    Kev, I think you are using a distorted understanding of the Bernouli principal.

    Yes the speed near the tip of a vacuum cleaner attachment is going to produce higher air velocity but only at the tip.
    Aren't we talking about the vent hole in the guts of the table? Not a vacuum tip near the head.
    Regardless of the velocity of the air just as it leaves the table, the total amount of air would be less if it goes through any hole that is small enough to make it speed up....resistance to flow (smaller hole) results in a decrease in pressure in the vacuum tube. It might seem to compensate exactly by increasing air speed but it's just not true. It is not a straight line 1:1 equation. Visualize the results as the hole gets ever smaller. You could easily test this by measuring the volume of air flow at the exit end or even just the velocity.
    In fact you can test this on a normal vacuum cleaner by listening to the sound of the motor as you block suction. The motor speeds up because there are less air molecules being pushed out by the fan blades. When the motor reaches max speed vacuum is also at a max but airflow is now zero.
    One thing that may be useful about faster exit speed is that the increased air velocity at the intake end would minimize the amount of smoke and particulate settling on the edges of the smaller entry orifice but once inside the tube I promise the airflow, although a bit more turbulent, from there to the final exit will be slower in velocity.
    Chinese 6040 by NiceCut. Originally 60 Watt upgraded to 150 Watt.....I thought I had pretty much every problem in the book of laser cutting. It turns out that there is a set of books.

  12. #12
    sucking smoke out of a laser box ain't rocket surgery guys, it's a simple matter of the smoke being drawn to the airflow.

    Fact: I have two HF blowers sucking air out of my Triumph, and I share one identical blower with my fiber and LS900... so essentially I have 4x airflow in the Triumph as the 900-- so with all this airflow science that I admittedly don't know much about, someone explain to me why it is that I have to wait nearly a full minute for smoke to completely evacuate from my Triumph, BUT, virtually ALL smoke in my LS900 is evacuated immediately as it's created, even with the door wide open! Why do you think this is? Because Gravograph designed their box to evacuate smoke extremely efficiently with minimal air flow. Part of this efficiency comes from using a 4" inlet rather than a 6" inlet, which would probably require a larger blower to draw the same amount of smoke. Who cares about airflow principles when they don't work in my real world? When I first got my fiber laser, I attached a 4" to 6" adapter to the vent line. The end of the vent was about 10" above and 6" to the right of the work table. I used the 6" pipe believing it would 'catch' more smoke, than a smaller pipe. Wrong-- most of the smoke drifted right past the large opening without being drawn in at all, but once I pulled the adapter off, which was about 10" long, the 4" pipe very visibly drew smoke from 6-8" away. I've found that be decreasing the opening size even more draws smoke faster, from even closer to the table. But the compromise is that the smaller the hole gets, even though it does pull smoke faster and from a bit farther away, less total smoke is drawn in, more smoke drifts away due to the narrower airflow path. So my happy medium is I close the gate about 1/4 to 1/3. So I have a slight issue with the speed near the tip of a vacuum cleaner attachment is going to produce higher air velocity but only at the tip, because the air that IS moving faster at the tip is coming from somewhere, and in my experience, from a fair distance in front of the tip, and that's the air the smoke will find

    I'm not trying to argue aerodynamic or Bernouli principles because honesly, I know nothing about them. I'm just trying to suggest ways to increase smoke evacuation without increasing airflow, which is definitely doable based on my experiences.
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  13. #13
    Join Date
    Feb 2006
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    Beavercreek, OH
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    My thoughts on this whole issue is the same principles that apply to dust collectors applies here. As I have been working on this machine I have found a number of potential issues to resolve.

    1. The cathode wire to the power supply was to short so they just pig tailed a 12" or so piece of 12/14 awg wire to make up for the difference. Not happy with that at all.
    2. The new laser tube that came with the machine, both the cathode and anode wires have no ends, gotta figure that one out, would like a mechanical connection. I managed to disassemble the old connector on one side. If I have to replace the wire to the power supply (cathode) I will have to run a new wire to the analog meter.
    3. There does not appear to be a resistor at the 5V wire and I am not sure what size to use. I see some say to use a variable one.
    4. During cleaning, OMG it was dirty, I found a small round piece of wood lodged between a limit switch and the rail. It may have been the problem all along.
    5. For the ground on the back of the machine, do I just run a wire to the ground on my electrical system or to one of the outside grounding rods for the main fuse panel?
    6. The new 80 watt power supply is twice as long and heavy as the old one. Not sure that's an issue.
    7. I am thinking of putting a section of metal ducting from the suction port at table height and a connector at the back to easily disconnect it. The duct they connected with was "plastic" and had no clamps to hold it on.
    8. For all the access doors, are there any issues with removing the dam key locks and putting rare earth magnets on them?


    PS I hope this isn't too many questions.

    Have a day blessed with the graces of God

  14. #14
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    Quote Originally Posted by Kev Williams View Post
    Because Gravograph designed their box to evacuate smoke extremely efficiently with minimal air flow. Part of this efficiency comes from using a 4" inlet rather than a 6" inlet, which would probably require a larger blower to draw the same amount of smoke.
    I'm not going to argue your experiences, but I am confident that your reasoning is flawed - since it is in conflict with know physical properties. Restricting a duct will increase velocity but it will reduce efficiency and cfm. A larger inlet (and ducting) would not require a larger blower to draw the same cfm. Just the opposite, the same blower will evacuate more air with a larger duct and inlet. That is just physics.

    Gravograph may very well have designed a better cabinet. I know my machine's designer has put zero effort into making it evacuate smoke efficiently - it is a box with a hole in it where you hook up a tube, lots of room for improvement there.


    Quote Originally Posted by Kev Williams View Post
    When I first got my fiber laser, I attached a 4" to 6" adapter to the vent line...
    I agree, that scenario would not provide a benefit. You would need to replace the entire 4" line going to the blower with 6" to realize the increased efficiency.
    Shenhui 1440x850, 130 Watt Reci Z6
    Gerber Sabre 408

  15. #15
    Join Date
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    Iowa USA
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    Go to your local auto parts store and buy whatever length you need of high voltage spark plug wire, just make sure its copper core instead of carbon. You might need to find a older store or farm store as the new ones with the kids on the counter will not have a clue. The metal used for tube connection is not really able to be soldered, successfully. You can gob solder on but its not a good connection. Mechanical connections such as split bolt connectors, screw or the like sold at Home Depot for splicing wires will work. Do not over tighten.

    If you have true 3 wire 120 volt outlets with a real ground wire attached to the U prong and the wire inside the machine from that 120 volt power cord is connected to metal or machine ground inside via the green wire that is all you need.
    Retired Guy- Central Iowa.HVAC/R , Cloudray Galvo Fiber , -Windows 10

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