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Thread: "Jitter" on Curves

  1. #16
    Join Date
    Feb 2012
    Location
    Nambucca Heads NSW Australia
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    190
    Quote Originally Posted by David Rust View Post
    Here is the .cdr file. It's pretty simple, all hairline curves.
    Try saving the file less than ver x6 for us mere mortals who still use versions from the arc!.

    Regards Steve
    I'm Back.... & Currently Using a 500 x 300 50w C02 Shenhui Laser
    with Corel Draw X5, RdWorks Ver8, Adobe Master Collection CS5, Ratsus Plugin for PhotoShop instead of Photograv.

  2. #17
    Join Date
    Dec 2008
    Location
    Canton, Ohio
    Posts
    259
    try this file on a piece of card stock and let me know if there is a difference.
    Attached Files Attached Files
    Life and death don't bother me. It's that little period of time in between that bothers me.

    Epilog Mini-24 40w with Rotary, Flame Polisher, CorelDRAW Graphics Suite X6, EngraveSoft, Windows 10 64-bit.

  3. #18
    Greg,
    Results are still degraded. Did you make any changes or did you just save as a v12?
    Epilog Helix 60w
    Epilog Mini 18 30W
    Purex Xbase 200
    CorelDRAW X7
    Wood Carver

  4. #19
    Ran the job at 50 speed, still jitter in the curves
    Ran the job at 25 speed, there is still jitter however the "magnitude" of the ripples is much less...

    The Helix sits on concrete, therefore there is no noticeable induced vibrations.
    The exhaust fan is mounted outside, the exhaust hose at the Helix has little to no vibration from the fan.
    The mirrors appear to mounted firm. I took a Q-tip wrapped in lens paper and tried to move them around, I also checked the adjustment screws and the mounting hardware. All appears to be tight and in good condition.
    I increased to belt tension just a small amount above what the spring tension is, no difference in performance.

    hmmm....
    Epilog Helix 60w
    Epilog Mini 18 30W
    Purex Xbase 200
    CorelDRAW X7
    Wood Carver

  5. #20
    Join Date
    Dec 2008
    Location
    Canton, Ohio
    Posts
    259
    I reduced the amount of nodes in the file.
    Quote Originally Posted by David Rust View Post
    Greg, Results are still degraded. Did you make any changes or did you just save as a v12?
    Life and death don't bother me. It's that little period of time in between that bothers me.

    Epilog Mini-24 40w with Rotary, Flame Polisher, CorelDRAW Graphics Suite X6, EngraveSoft, Windows 10 64-bit.

  6. #21
    Its a long shot, I'm sure you would have noticed, but is your material secure? Because if you are cutting something lightweight like paper, you can get some rippled cuts that look like this when your exhaust blower develops enough suction through the cut line to vibrate the paper like the reed in a kazoo. It can actually make a kazoo-like noise, and you will see a wavy pattern in the material. I reckon the air assist can potentially cause a similar problem. Dave
    Epilog 35 W 12x24
    Adobe Illustrator
    Dell PC

  7. #22
    Quote Originally Posted by David Rust View Post
    Ran the job at 50 speed, still jitter in the curves
    Ran the job at 25 speed, there is still jitter however the "magnitude" of the ripples is much less...
    Just for the record, I have never seen a laser that cuts clean, smooth lines at 25% speed. Our Epilog wouldn't do it, our Universal won't do it, and our Trotec won't do it. I think you need to get a lot more realistic with your speed. It's been so long since I have run an Epilog, I don't recall good settings for it, but try a speed of 10-15 and see what you get.

    I have run a lot of tests over the years on this very thing and it's always been there, in all 3 major manufacturers, for years and years. High speed vector cutting only works great on straight lines.

    Try it at 10-15 and see if that solves the problem. I don't think you have any mechanical issues, I think you're just trying to cut way faster than the machine is made to cut.
    Lasers : Trotec Speedy 300 75W, Trotec Speedy 300 80W, Galvo Fiber Laser 20W
    Printers : Mimaki UJF-6042 UV Flatbed Printer , HP Designjet L26500 61" Wide Format Latex Printer, Summa S140-T 48" Vinyl Plotter
    Router : ShopBot 48" x 96" CNC Router Rotary Engravers : (2) Xenetech XOT 16 x 25 Rotary Engravers

    Real name Steve but that name was taken on the forum. Used Middle name. Call me Steve or Scott, doesn't matter.

  8. #23
    Join Date
    Dec 2008
    Location
    Canton, Ohio
    Posts
    259
    FWIW - when cutting vectors, make sure the resolution is set to 1200 DPI. Do a search here and you will find that setting the resolution at this level yields superior results than at say, 300 and lower.
    Life and death don't bother me. It's that little period of time in between that bothers me.

    Epilog Mini-24 40w with Rotary, Flame Polisher, CorelDRAW Graphics Suite X6, EngraveSoft, Windows 10 64-bit.

  9. #24
    We had this problem on our Epilog 36EXT. Your pulleys have multiple set screws that keep them tight against the rods. The rods have a flat spot that interface with the pulleys. When we had this problem the set screws were loose. Not enough that we could feel slop when we moved the gantry by hand but it was enough that when the machine ran we would see it. Our solution was to re-tighten all the set screws and loctite them. Use a serviceable loctite though in case you ever have to service the machine.

  10. #25
    David- were you able to determine a cause and get this resolved?

    Dave
    Epilog 35 W 12x24
    Adobe Illustrator
    Dell PC

  11. #26
    I have had my machine do it at times too. I believe it is more to do with the file then your machine. While toolmaking, we would have certain programs that would be generated with a massive amount of points vs. a program with curves in it and the CNC 's would do the same thing - jitter on a radius cut. I think it has to do with the way the program is made from a design to moves (posting).
    Epliog Legend EXT 36x24 75 Watt
    Corel Draw x6
    Xenetech 16x25 rotary - use it everyday!!
    Mastercam X5 - Cam programmer/toolmaker in my former life

  12. #27
    Quote Originally Posted by David Fairfield View Post
    David- were you able to determine a cause and get this resolved?

    Dave

    Hi Dave, I was not able to get to the bottom of the the problem. I sent Epilog an example file with settings and they said that they also experienced "ripples". My confusion lies in the fact that I have two cut outs, on recent with ripples and one from a few months back without ripples. It is possible that I had different settings however I saved the setting configuration settings in the epilog print interface. I haven't dug back into it again since talking with them, once I get some time I'll do some more tests and get back to everyone.
    Epilog Helix 60w
    Epilog Mini 18 30W
    Purex Xbase 200
    CorelDRAW X7
    Wood Carver

  13. #28
    I think I got to the bottom of the Jitter problem...

    Problem Recap:
    - Jitter on curved cut edge while vector cutting paper, new problem, I have previously cut the same Corel file without the jitter. No issues on straight edges parallel or diagonal to the x-axis
    Troubleshooting:
    - re-aligned
    - re-leveled table
    - cleaned all lenses/mirrors
    - cleaned x-axis encoder strip
    - replaced x-axis motor (for different issue)
    - verified file had round hairline circles in tst file
    - cut circles at different speeds
    - cut circles in different areas of the table
    - sent files and pics to Epilog
    - conversed with them over the course of a month
    - Epilog said they ran the same settings and got jitter also, so it must be a limitation of the machine
    - replaced the x-axis bearings (under warranty)
    - varied tension on the x-axis belt
    - cut circles at 25 speed and still had jitter issues
    None of this fixed the problem...

    Discussion:
    I decided to do more tests and change other settings... I discovered that the settings for "vector only"cutting are not just, Speed(0-100), Power(0-100), and Frequency(0-5000 pulses per inch).
    DPI(75 - 1200 dots per inch) also plays into the equation... Once I discovered this I searched the manual and could not find where it mentioned that DPI was a factor in vector cutting. However when choosing a "vector only" cut, DPI is not grayed out. When I increase DPI over 600 all Jitter goes away....

    This is what I think is going on (may not be the case, just my observations):
    The DPI is a setting that affects x/y-axis movement and the Frequency is a tube setting that affects the firing of the laser. Two separate settings that both are used for vector only cutting. The only confusion I have now is that the Epilog manual states that Frequency is "pulses per inch"... this is why I originally didn't think that DPI was a factor. Is Frequency really supposed to be"pulses per second" as opposed to "pulses per inch"? Another thought... maybe frequency for the tube is consistent with the freq settings and the laser output is gated by the DPI setting....

    If frequency is really "pulses per inch" as the manual indicates then speed should have an effect on frequency...

    Resolution:
    - Set DPI to >=600
    - 100s/18p/500freq/DPI600 cuts paper at high speed without jitter
    Epilog Helix 60w
    Epilog Mini 18 30W
    Purex Xbase 200
    CorelDRAW X7
    Wood Carver

  14. #29
    I know this is a OLD thread, but I'd like to say THANK YOU to David Rust! This really worked charms to our cut quality!

    I can't believe that this worked! 1000x Thank you!
    Henri Sallinen
    Cardboard designer with a Epilog Helix 24 60w + Gunnar Matboard Cutter + Heidelberg Windmill letterpress

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