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Thread: laser continues cutting after the image is completed on rotary

  1. #1

    laser continues cutting after the image is completed on rotary

    Good morning,

    New member, first post. New laser owner of 2 weeks.

    I don't like asking questions on forums unless I have exhausted all of my options and attempted to fix my own problems.

    I can engrave on a flat surface like nobody's business. Aluminum, titanium gun parts, granite, Pmags, computers and iPhones.

    After more than 200 hours of trial and error on my new Chinese 50w fiber laser (JPT from Amazon) I believe I may have reached my limit.

    I am trying to engrave a tumbler on the rotary. I am fighting small gaps in the splits if I open them up to anything over .09. Splits of 20 gives ok results with just fewer vertical lines in the piece. If I make the splits like 5, there are many vertical lines in the image, as well as what looks and feels like the rotary it bouncing from one stop to the next.

    I like the results at .09, but anything under 1.0 creates a situation where the laser drags a line from where it's finished, to the spot where the laser comes to rest. It can not be cured by un-clicking the check box "return to start point." That only affects the rotary stopping point.

    I've watched videos on laser timing, I've etched test pieces that look great at multiple speeds and power levels.

    I've changed every number I can in the laser start and stop tables, both higher and lower. I've messed with parameters.

    I don't feel I have screwed anything up in the original settings, when I'm finished messing around, I close the file with out saving the changes, so it goes back to all the original settings. (I checked)

    I'm at a loss here. Hopefully someone has some advice for a newbie.

    Thanks in advance.
    Last edited by Rob Steffens; 01-29-2021 at 11:20 AM.

  2. #2
    It is almost literally impossible to "seamlessly" together split sections when engraving by fiber rotary. The simple reason is, the math doesn't work...

    The mirrors are incredibly precise in what they do. The rotary, and the part you're engraving however, are not even close. To get a perfect seam every time, the part diameter, in all directions (static dia, rolling radius, azimuth), cannot vary more than say .01mm. Any changes will result in a visible engraved overlap, or visible space between lines. The rotary's themselves aren't bad at accuracy, but they need to adjusted to a higher res than the factory 6400 ppr mine was set at. I have mine set for 20,000. Much smoother transition and less start/stop shock. Note, in the F3 menu, "other" tab, at the top is a place to enter a 'start mark delay', 300ms works pretty good to give the chuck time to stop before the next engraving starts. This might help your current problem somewhat.

    Learning to use the 'rotary text mark' feature is a good thing, when engraving text the rotary automatically engraves each letter individually. It also works with individually hatched graphics that may overlap in the rotary plane but don't touch each other; if you can separate the pieces so they'll stay in focus around the radius, just individually hatch the pieces. Great tool for doing that, is the "Hatch one by one" check box in the hatch menu, that's what it's for one note on hatching one by one, if any graphics you consider 'one' graphic has holes in it, those graphics will need to be grouped first, then just batch-hatch all graphics one by one.

    hope this helps--
    ========================================
    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 for your reply.

    I will change the 6400 to 20,000 as suggested. I thought I read somewhere that the 6400 setting was predetermined and couldn't be changed.

    Any thoughts on why the laser is engraving from the image, back to it's resting point? (probably a more technical term for this, I'm sure)

  4. #4
    first, the change from 6400 to 20000- Inside the machine you'll find the rotary wires plugged into its own controller, which you need to access to change the PPR values via dip switches--
    Mine is similar to this one
    rotdriver.jpg
    -the steps per rev settings are on the left, switches are on one of the sides, out of view. The software settings and dipswitch settings must match. No warranty issues with pulling a cover to change controller settings btw...

    As to the 'image'-- are you engraving an actual photo image, or vector graphic?

    I've never attempted a photo image on the rotary. But many many times simply engraving photos of any type on any laser has resulted in the very first, or very last thing engraved, is one side of the photo's boundary. Very frustrating to spend 20 minutes creating a perfect image only to have the laser saw a damn line across the top or bottom.

    There is a familiar anomaly with the 'fast' hatch routine - the 'short' hatch that stays connected on the edges rather than broken- at times, for no rhyme or reason, that hatch can create a non-laser-off jump line from one spot to another. Usually that line is visible on-screen, but sometimes not.

    The only other thing I can think of is you may need to adjust your laser's Start-Laser Off-End-Polygon "TC" settings, those below the basic speed/power settings. And below the TC settings is an "advanced" button, hit that and in the upper right corner are the "Jump" settings... I've never had to mess with those, but all lasers are different. I'd check thru the EzCad manual for explanations on those
    ========================================
    ELEVEN - rotary cutter tool machines
    FOUR - CO2 lasers
    THREE- make that FOUR now - fiber lasers
    ONE - vinyl cutter
    CASmate, Corel, Gravostyle


  5. #5
    Thank you again. Yes, changing just the 6400 to 20,000 without changing the dipswitch settings only managed to expand the image longways.
    I will have to open up the machine after I look at your picture.

    I don't have enough permissions to view the photo you attached.

    The image I am engraving was a vector file I created in Adobe Illustrator.

    So, here is the solution that I came up with after another full day of testing.

    I had tried the rotary on the Y axis from the left and then the right side. After moving it to the X axis, and inverting the image, I stopped seeing the line jump from the end of the image being cut.

    You mentioned engraving a photo on the rotary..... If it's handled like a bit map, I'm not sure how to do it the right way. My first couple of attempts to use the rotary was with a bitmap. The rotary didn't really respond that well. It never rotated and tried to engrave it like it was on a flat surface. The image disappears once the radius falls off.

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