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Thread: Problem with RIP screen angle

  1. #31
    Banned submeg is on a distinguished road
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    I dont know your configuration, but you need to check Laser power values, and deevloper setings.
    If they are OK, just make some page setup, Print Uncalibrated target for that page setup (monohrom), Measure and enter values for uncalibrate target (no matter what values just enter what you measure).
    Then print calibrate target for came page setup (monochrom), and measure it, and enter in enter calibration data. Then you can repeat print calibrated target, and measure it again, if deviation is about 1% do nothing, if bigger enter new measured data, and repet print calibration .....

  2. #32
    PRC Member DoctorBlade is on a distinguished road DoctorBlade's Avatar
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    Quote Originally Posted by sid6581 View Post
    I just cannot calibrate in to monochromatic mode. The values deviate too much from each other.
    My setup:
    • ECRM VR36:
    • ECRM RIP 8.3
    • Exposure: 130
    • Screen Frequency:150
    • Screen Angle: 45
    • Resolution: 2540x2540
    • Screen Spot: Euclidean

    Values:

    0-0; 2-9; 4-13; 6-17; 8-21; 10-25; 15-33; 20-42; 30-56; 40-72; 45-79; 50-81;

    55-80; 60-84; 70-90; 80-96; 85-98; 90-100; 92-100; 94-100; 96-100; 98-100; 100-100.
    Why are your readings far from original values. Also please check at 50 you have 81 and then it went down again to 80 at 55. Is your curve the one below?


  3. #33
    Junior Member sid6581 is on a distinguished road
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    Quote Originally Posted by submeg View Post
    I dont know your configuration, but you need to check Laser power values, and deevloper setings.
    If they are OK, just make some page setup, Print Uncalibrated target for that page setup (monohrom), Measure and enter values for uncalibrate target (no matter what values just enter what you measure).
    Then print calibrate target for came page setup (monochrom), and measure it, and enter in enter calibration data. Then you can repeat print calibrated target, and measure it again, if deviation is about 1% do nothing, if bigger enter new measured data, and repet print calibration .....
    The first problem is with the film. I do not know who made the film so I am not able to find the specifications for the film. The second thing I was worried about is the density. Measured density in past 5 times for uncalibrated target was 4.8 which was too high(been told by a friend who said that 4.5 should be the max). Now I have to find a way how to find good exposure for the film and how to setup that density. If anyone has any idea, please notify me asap :)

  4. #34
    Junior Member sid6581 is on a distinguished road
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    Quote Originally Posted by DoctorBlade View Post
    Why are your readings far from original values. Also please check at 50 you have 81 and then it went down again to 80 at 55. Is your curve the one below?

    Unfortunately, yes. I am aware about that. I have to find exposure sweetspot. Some said that for finding good exposure I have to check for 50% dot gain swatch at the test sample. Please tell me if I did something wrong. As I said, density is too hing cause of the exposure. I have to do the sweep again. :/

  5. #35
    PRC Member tomcatinc is on a distinguished road
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    calibration and harlequin rip

    Calibration:
    When searching for right density, machines usually have their internal tests which are for example:
    resolution: 2540 DPI
    start laserpower: xxx
    end laserpower: yyy
    step: zzz
    Start laser power is the lowest laser power to start (lets say 900 of something), end power is the highest laser power to end with (lets say 1800 of something), step is increment to the next test (lets say 100 of something). In this example you will get 10 steps of laser power. Measure them and the one closest to 4.1 is a good one. Don't go below 3.9 for offset printing, flexo printing usualy goes a bit higher. If you don't have such a test on machine, perform it from RIP: RIP 100% inked square of at least 6x6mm with different laser settings.

    Regarding angle deviation, go to Harlequin Precision screening setting and set:
    Angle accuracy: 0.004 degree
    Freequency accuracy: 0.1 lpi
    Zero degrees frequency ajustment: 7 percent (you will have to play here a bit to find right value since there is no control weather this frequency is going 7% up or down)
    Maximum frequency deviation: 0.4 percent
    Enable HPS 2.0

    Try settings if the angles and screen frequncies work for you. You don't have to output it, just watch the log.

  6. #36
    Junior Member sid6581 is on a distinguished road
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    Quote Originally Posted by tomcatinc View Post
    Calibration:
    When searching for right density, machines usually have their internal tests which are for example:
    resolution: 2540 DPI
    start laserpower: xxx
    end laserpower: yyy
    step: zzz
    Start laser power is the lowest laser power to start (lets say 900 of something), end power is the highest laser power to end with (lets say 1800 of something), step is increment to the next test (lets say 100 of something). In this example you will get 10 steps of laser power. Measure them and the one closest to 4.1 is a good one. Don't go below 3.9 for offset printing, flexo printing usualy goes a bit higher. If you don't have such a test on machine, perform it from RIP: RIP 100% inked square of at least 6x6mm with different laser settings.

    Regarding angle deviation, go to Harlequin Precision screening setting and set:
    Angle accuracy: 0.004 degree
    Freequency accuracy: 0.1 lpi
    Zero degrees frequency ajustment: 7 percent (you will have to play here a bit to find right value since there is no control weather this frequency is going 7% up or down)
    Maximum frequency deviation: 0.4 percent
    Enable HPS 2.0

    Try settings if the angles and screen frequncies work for you. You don't have to output it, just watch the log.
    I have results from the last exposure sweep. They are all bad . Almost all 50% dot gains are above 80% and densities are from 5 to 5.3. I dont know what to do next. Can you help?

    I will try to re-tweak those settings for HPC and I will inform you if anything changes.
    Last edited by sid6581; 08-27-2012 at 02:51 AM.

  7. #37
    Moderator kazanchi has a spectacular aura about kazanchi has a spectacular aura about
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    Quote Originally Posted by sid6581 View Post
    The first problem is with the film. I do not know who made the film so I am not able to find the specifications for the film. The second thing I was worried about is the density. Measured density in past 5 times for uncalibrated target was 4.8 which was too high(been told by a friend who said that 4.5 should be the max). Now I have to find a way how to find good exposure for the film and how to setup that density. If anyone has any idea, please notify me asap :)
    And
    Quote Originally Posted by sid6581 View Post
    ...
    My setup:
    • ...
    • Exposure: 130
      ...
    ....
    And

    Quote Originally Posted by sid6581 View Post
    I have results from the last exposure sweep. They are all bad . Almost all 50% dot gains are above 80% and densities are from 5 to 5.3. I dont know what to do next. Can you help?

    I will try to re-tweak those settings for HPC and I will inform you if anything changes.

    Did you try any other exposure? 80 for example?

  8. #38
    Donor Shap will become famous soon enough
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    Film Imagesetter Calibration and Linearistion

    (Assuming that your laser exposure and film processing are stable and repeatable)...

    The first step is finding the correct Basic Laser Intensity for your specific combination of Film, Laser and Processing.

    This is achieved by exposing (UNCALIBRATED) patches of solid areas with different intensity values and measuring the resulting densities.

    My own target is 4.00 Dens for a solid 100% . I believe this value is adequate for most applications.

    Only AFTER you found out what is your Basic Exposure - you can start using this value and Linearise (calibrate) by exposing Known File Values and measuring the outcome on film.

    Every imagesetter manufacturer has a utility for creating a Correction Curve based on these measurement, to get your output into proportion to the requested values.

    My $ 0.02...

  9. #39
    Moderator kazanchi has a spectacular aura about kazanchi has a spectacular aura about
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    Quote Originally Posted by Shap View Post
    ...
    The first step is finding the correct Basic Laser Intensity for your specific combination of Film, Laser and Processing.
    ...
    And, as I know, ECRM's filmsetters have two ways to correct power of the laser:
    1. Like "hardware" - into machine's menu
    2. Like "software" - in page setup of the RIP

  10. #40
    Junior Member sid6581 is on a distinguished road
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    That ECRM VR36 was hooked on MAC and I had to update EPROM version to 1.11. I do not know if there are any changes considering laser operation prior to firmware upgrade. If there are any, please let me know.

    The thing about modes really keeps me confused. In LOCAL MODE, I have found a setup for tuning EXPOSURE, from 0 to 331. The 1000000$ question! Does RIP pull out any values form LOCAL MODE, in this case EXPOSURE values, so he could combine it with the values inside of the RIP, or do they work totally separately?

    If you can point me how I could find the proper exposure form my film so I could continue my way to linearization. Thank you all!

  11. Your ad here

  12. #41
    Junior Member sid6581 is on a distinguished road
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    Quote Originally Posted by sassoonman View Post
    dwvqklhrbkdfbv nmv ;kl]e[f]
    w;
    f
    o.O??? What the heck?

  13. #42
    Banned submeg is on a distinguished road
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    Just leave expositure in HQ as is, and use hardware laser adjustment till got, let say, 4.00 Densiti in 100% patch.
    Then print uncalibrated target, measure and enter data, and then calibrated target and measure and ented data.
    If data is less then +/- 1% you finish, if not print again calibrate target and measure ..............

  14. #43
    Junior Member sid6581 is on a distinguished road
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    Quote Originally Posted by submeg View Post
    Just leave expositure in HQ as is, and use hardware laser adjustment till got, let say, 4.00 Densiti in 100% patch.
    Then print uncalibrated target, measure and enter data, and then calibrated target and measure and ented data.
    If data is less then +/- 1% you finish, if not print again calibrate target and measure ..............
    Oh... So, if I make adjustments in LOCAL MODE, these values will effect in SERIAL MODE in Harlequin RIP? Values are different when doing on the machine. They go from 0-331.

  15. #44
    PRC Member tomcatinc is on a distinguished road
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    anyhow, try to get 100% patch to density around 4.2 - use the method you are comfortable with. Then see where is your 50%.

  16. #45
    Banned submeg is on a distinguished road
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    Do you know how to adjust Laser power on Device (Hardware)?

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