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Thread: 2500 x 1300 flad bed laser 2 interesting issues... & RD works. Ideas appreciated!

  1. #1

    2500 x 1300 flad bed laser 2 interesting issues... & RD works. Ideas appreciated!

    Hi Folks, after running our new laser for about 10 weeks, and really testing it out, I've found some issues that the helpful Chinese sellers have been as stumped with as I have.

    IN a nutshell, it engraves/scans/etches beautifully, via RD Works, and also via Lightburn.
    I have that tuned down well, and the 10 x 4 ft file I spent 16 hours running on our Goldenlaser last Jaunary/Feb, etching acrylic, I decided to run as a test on cardboard on this machine and it did it in just 9 hours, in one piece- no splitting the file into 24 separate pieces because of memory issues. I am happy with that aspect. It took a bit to get the reverse interval calculations spot-on, but they're good now. I can engrave a solid box shape and get no curtains effects at all- just a nice even etch.

    As far as cutting goes, therein lies the problem. It has a big gantry with 2 tubes and 2 heads and both steppers in it. X movement is fine - it only has to move the 2 heads.
    In Y direction, when I cut circles or squares, (or letters) there is a noticable wobble or vibration as the gantry or Y moves towards the front.
    I mean in a circle, it shows up as a wobble in the 1 to 3 o'clock quadrant.
    IN a square, it is dead quiet when cutting along the X axis, and the Y axis moving away is a slight noise, but when Y moves toward the front you can hear a grinding sort of rumble.

    I'd describe it like the grumbling noise from a servo that does not have the PID settings right, and it is arguing with itself trying to hold itself still.
    It's not that bad, but that's what it's like.

    I have really dropped the speed and acceleration in the vendor settings and the User cutting acc & speed settings right down extremely low, and that has reduced 96% of the wobble, but it is still not quite right or good enough for my liking.
    It should not make a resisting noice when Y comes forward, but no noise in reverse. Logic says the effort or load on the stepper should be the same both ways...

    The effects are the same whether I cut a file in the any corner or middle of the bed.

    Any ideas would be appreciated. The pulleys/gears are tight, not slipping, and the timing belt is as taut as a guitar string. It is not a physical problem that I can see. There is no perceptible slop in Y. The gantry has no perceptible flex.
    Most of my parameters/figures are way less than many think I should have them, but I figured the inertia of the gentry takes some slowing and reversing, so I did not want idle speed and acceleration too high if it has to be resisted at the other end of the journey before the next cut.

    ____________
    As an aside, I asked for the laser to be built with servos. They said the cost would be too high, and that steppers are fine, so I asked for closed-loop steppers - Leadshine easyservos. They installed them, and it seemed all was good- fast engraving.
    They then set the machine to cut a file and then turned the tubes off and ran it in random paths for 48 hours, and then reran the original cut file
    The result was they said the easyservos couldn not handle the weight of the gantry and objected to losing steps when changing quickly.
    They put the steppers back in. I asked if they could have one of each- easyservo for X and stepper for Y. They said no - they had to be the same type.
    So I asked if they'd send the easyservos & drives out with the machine - that cost me about $350 extra, but I now have them to use on another project one day.


    So, I'm happy with the machine, and what it has simplified that out that the other two could not do, but I'd be a lot happier if i could solve the grumbling bumpy Y axis movements toward the front of the bed. At very low speeds they are imperceptible to any customer, but it's not good enough for me!

    Thanks for any thoughts- does anyone here have a similar system they'd share vendor and user parameters with me over?
    Last edited by Ian Stewart-Koster; 08-29-2018 at 8:55 PM. Reason: typos
    Best wishes,
    Ian



    ULS M-300, 55w made 2002 with rotary. Goldenlaser 130 watt, 1300x700 made 2011.
    Flat bed 2500x1300 150/90watt 2 tube laser, 2018 model.
    Esab router, 1989, 4.5 x 2.0 m, conv. to Tekcel, and modded a 2nd time.
    HP L260-60". Roland PNC-1410. Mimaki GC-130 SU.
    Screenprinting carousel 6x4 and 7x4 ft 1-arm bandit vac table.
    Corel Draw X3, Illy, Indesign & Photoshop CS2 & CS5, Enroute 4
    Pencil, paper, paintbrush, airbrush & dagger-liners & assorted other stuff.

  2. #2
    Just a thought (and likely wrong) but I'm wondering if the machine is moving based on plain old 1014 HPGL plotting? For large stuff I can only imagine how bumpy a circle would be! Years ago I used to painstakingly smooth everything I digitized, only to be appalled at the bumpy results of the actual PLT files as drawn on screen - the same PLT files my machines run! I've since quit all that smoothing!

    Other thoughts: your 'guitar string taut' timing belt-- try loosening it. My IS7000 engraver, the initial X timing belt is short like the short Y belt on most lasers- While most of those Y belts are tight as hell, the belt on my 7000 has so much slack that it seems wrong, yet this machine is the most dead-to-rights accurate machine I own. Even with that sloppy belt, it's the ONLY machine I have that will cut perfectly round holes thru 1/8" aluminum with a 1/16" endmill in one pass. Another example, my Triumph 1390, if the X belt is too tight- which never really feels all that tight because it's so long- will cause the stepper to groan & vibrate on long runs at certain speeds, and at times I've had the stepper actually lock up. Once the belt is slacked off just right, all the vibration and noise vanishes. In tests (I have video's somewhere) I've determined that MY steppers at least, like, or need? - a certain amount of load, too much or too little and the stepper goes into racket-mode. I even bought a new stepper because of this, against Triumph's insistence nothing was wrong with it- And the new one does the same thing

    lastly, with your machine's groaning, it almost sounds like a there's a conflict between what the stepper is being told to do and what it CAN do- I'm familiar with this problem too, with my LS900's rotary; my machine's controller is older than the rotary and it's sub-controller card, and at times the X axis makes thumping noises, and occasionally even jumps out of position, due to some sort of steps-per-inch conflict. (I can get it fixed by upgrading or rebuilding my original controller, but haven't)

    I wish I understood steppers more

    Anyway, try loosening that belt, it'll always tighten back up if it doesn't help!
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  3. #3
    Thank you Kev. Against logic, I'll try loosening the Y belts - they're very long...
    but what has me stumped is that Y can move swsy from the front quite contentedly - it is only the forward movement that sets it vibrating. Not both ways.
    Best wishes,
    Ian



    ULS M-300, 55w made 2002 with rotary. Goldenlaser 130 watt, 1300x700 made 2011.
    Flat bed 2500x1300 150/90watt 2 tube laser, 2018 model.
    Esab router, 1989, 4.5 x 2.0 m, conv. to Tekcel, and modded a 2nd time.
    HP L260-60". Roland PNC-1410. Mimaki GC-130 SU.
    Screenprinting carousel 6x4 and 7x4 ft 1-arm bandit vac table.
    Corel Draw X3, Illy, Indesign & Photoshop CS2 & CS5, Enroute 4
    Pencil, paper, paintbrush, airbrush & dagger-liners & assorted other stuff.

  4. #4
    Join Date
    Sep 2016
    Location
    Georgia, USA
    Posts
    394
    Let us know how it goes. I think my system has a little bit of this too. I have read you keep the small single belt that from the motor drives the big long shaft tight but the long belts on each side that actually move the gantry/Y axis looser in comparison.
    700mm x 500mm Ke Hui KH-7050 Laser
    80W EFR F2
    S&A CW5000 chiller
    Chuck style of rotary attachment

  5. #5
    I wonder what the actual logic in that is, Doug?
    (what is your machine size, and controller?)
    Best wishes,
    Ian



    ULS M-300, 55w made 2002 with rotary. Goldenlaser 130 watt, 1300x700 made 2011.
    Flat bed 2500x1300 150/90watt 2 tube laser, 2018 model.
    Esab router, 1989, 4.5 x 2.0 m, conv. to Tekcel, and modded a 2nd time.
    HP L260-60". Roland PNC-1410. Mimaki GC-130 SU.
    Screenprinting carousel 6x4 and 7x4 ft 1-arm bandit vac table.
    Corel Draw X3, Illy, Indesign & Photoshop CS2 & CS5, Enroute 4
    Pencil, paper, paintbrush, airbrush & dagger-liners & assorted other stuff.

  6. #6
    I undid the Y axis long belt tensioners by 4 full turns - about 4mm - for no appreciable difference in cut or stepper effort, yet.
    They are the bed length, plus the loop up into the gantry and back down - possibly 3 metres each- certainly 9 ft at least.
    Best wishes,
    Ian



    ULS M-300, 55w made 2002 with rotary. Goldenlaser 130 watt, 1300x700 made 2011.
    Flat bed 2500x1300 150/90watt 2 tube laser, 2018 model.
    Esab router, 1989, 4.5 x 2.0 m, conv. to Tekcel, and modded a 2nd time.
    HP L260-60". Roland PNC-1410. Mimaki GC-130 SU.
    Screenprinting carousel 6x4 and 7x4 ft 1-arm bandit vac table.
    Corel Draw X3, Illy, Indesign & Photoshop CS2 & CS5, Enroute 4
    Pencil, paper, paintbrush, airbrush & dagger-liners & assorted other stuff.

  7. #7
    thanks to a few suggestions, its now cutting big and small circles and text acceptably, even at high speeds!
    The solution, (other than a swidgin of backlash) was twofold.

    1. I had loosened both y belts 4mm, for no improvement in grumbling noise nor wobbles.
    I lasered a 1000mm square, and the diagonals were out by 3 mm. Plus the Y length was short by 0.3mm.
    I thought about it a bit, and then retensioned the left Y belt (only), by 4.5mm overall. Basically one full tooth pitch and a bit. The right belt I left alone.

    I redid the 1 metre square cut and it came out the right size on all edges, AND with equal diagonal lengths now.
    AND what's more, the groaning in the Y stepper vanished.
    It was as if the teeth had been marginally out of synch before, but are aligned just right now!

    2. Lasering small text and shapes still gave a mess at speeds above 15mm/s. It was ok slower than that.

    I took a gamble and pulled the User>cutting parameters
    Idle acceleration down to 100, and max cutting acceleration = 100, acceleration factor = 35%.

    I left the speeds at previous figures- start speed 1mm/s.

    Suddenly I could laser the same sample I've been trying for weeks at speeds up to 300mm/s and not have a mess!

    Admittedly when cutting 25mm thick acrylic we're travelling along in single figures of speed, but it is still good to have clean text at higher speeds.

    I've been racking my brain for ages trying to solve it!
    Best wishes,
    Ian



    ULS M-300, 55w made 2002 with rotary. Goldenlaser 130 watt, 1300x700 made 2011.
    Flat bed 2500x1300 150/90watt 2 tube laser, 2018 model.
    Esab router, 1989, 4.5 x 2.0 m, conv. to Tekcel, and modded a 2nd time.
    HP L260-60". Roland PNC-1410. Mimaki GC-130 SU.
    Screenprinting carousel 6x4 and 7x4 ft 1-arm bandit vac table.
    Corel Draw X3, Illy, Indesign & Photoshop CS2 & CS5, Enroute 4
    Pencil, paper, paintbrush, airbrush & dagger-liners & assorted other stuff.

  8. #8
    Gantry wasn't / isn't?- exactly square, on a machine of that size I can only imaging the side-loading forces being exerted on the rail bearings, they don't go diagonally without a fight! So it sounds like you still need to square the gantry up with the all the belts loose or disconnected, then tension the long belts equally- That and the speed adjustments you've made should have that thing running like a new Bentley!
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  9. #9
    Thanks, Kev. I think it was in fight mode before I realigned it, and the belt teeth in the Y gears were not in unison left and right, due to unequal tensions or slightly mismatched stretched lengths.
    But measuring the diagonals as being skewed out by 3mm, then tensioning the left belt nearer to 4.5mm tighter , allowed the diagonal to shrink, made it run square and so much more quietly. (that's my explanation anyway!)
    I think I relieved the out-of-kilter tensions.
    Best wishes,
    Ian



    ULS M-300, 55w made 2002 with rotary. Goldenlaser 130 watt, 1300x700 made 2011.
    Flat bed 2500x1300 150/90watt 2 tube laser, 2018 model.
    Esab router, 1989, 4.5 x 2.0 m, conv. to Tekcel, and modded a 2nd time.
    HP L260-60". Roland PNC-1410. Mimaki GC-130 SU.
    Screenprinting carousel 6x4 and 7x4 ft 1-arm bandit vac table.
    Corel Draw X3, Illy, Indesign & Photoshop CS2 & CS5, Enroute 4
    Pencil, paper, paintbrush, airbrush & dagger-liners & assorted other stuff.

  10. #10
    50 mm_n.jpg
    For the record, above shows the wobble caused by Y axis issues, and that was at 50mm/s speed.
    It was worse when lasering faster, and even slowed down to 5-8mm/s it did not go away.
    That's what I was trying to diagnose out of it.

    100 mm rough.jpg

    That was at 100 mm/s, partially improved, but still atrocious, for quality.
    I could get it much better at 14 mm/s or slower, but all that did was dampen the problem to roughly acceptable levels, rather than eliminate it.


    300 mm_n.jpg

    That above is after I had finally severely dropped the cutting and idle acceleration , and lowered the start speed a lot, and adjusted the left Y belt tension.
    That is at 300 mm/s, showing neatness at high speed that was previously impossible at even a sixth of that speed.
    Of course I cut much more slowly, but this just shows the improvement.

    I'm now going to try & see how the RD Works 'acceleration factor' figure in User tab settings changes things- unless someone can tell me. It's at about 35% at the moment.

    Catch96C3.jpg
    That's a photo of it just before they boxed it up & shipped it over here.
    Best wishes,
    Ian



    ULS M-300, 55w made 2002 with rotary. Goldenlaser 130 watt, 1300x700 made 2011.
    Flat bed 2500x1300 150/90watt 2 tube laser, 2018 model.
    Esab router, 1989, 4.5 x 2.0 m, conv. to Tekcel, and modded a 2nd time.
    HP L260-60". Roland PNC-1410. Mimaki GC-130 SU.
    Screenprinting carousel 6x4 and 7x4 ft 1-arm bandit vac table.
    Corel Draw X3, Illy, Indesign & Photoshop CS2 & CS5, Enroute 4
    Pencil, paper, paintbrush, airbrush & dagger-liners & assorted other stuff.

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