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Thread: Laser Engraver DAC settings not fast enough

  1. #21
    Member TomKerekes's Avatar
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    Default Re: Laser Engraver DAC settings not fast enough

    Hi Dan,

    You could just add that in a loop. Such as:

    Code:
    for (;;)
    {
        WaitNextTimeSlice();
        DAC(7,ch7->Dest);
    }
    But I don't think that would make any difference. If you explain what configuration you are using and post some GCode we could take a look at it. If properly configured the X axis motion should be at the commanded feedrate and the analog output from Kanalog should settle to the commanded value within several hundred microseconds. If you do the math (200us x Velocity) would that explain something like you are seeing?

    At some point you mentioned 50ipm. At that speed the error would be 50/60ips x 200us = 0.2mils

    If the Laser itself has a time delay one trick I have used is to implement a digital delay of the Trajectory. By delaying the Trajectory, and not the Laser commands, the Laser commands then occur in advance of the position. You might consider that at some point. But it sounds like you have some more drastic issue if you can't even get a recognizable result.

    Regards

    Regards
    TK http://dynomotion.com


  2. #22
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    Default Re: Laser Engraver DAC settings not fast enough

    Hi Tom,

    A little update on our trouble shooting status:

    We installed amp meters and volt meters and everything from the Kanalog out to the laser appears to be working properly.

    I started messing around with the settings in the KmotionCNC.

    Before with all of the advice you had given we had steady motion but little to no variation in the DAC output.

    I went into the Trajectory Planner Menu in KmotionCNC and changed the C Axis "Radius Inch" value from zero to different values (the box after the Degrees check box) and the DAC reading started to really jump around but we ran into the same issue as before where it's not a continuous motion in the X & Y (there is some slowing down) but the laser is going from high to low very quickly. The best setting is 0.1 for the Radius inch box that we have gotten to work there is still some slowing of the drive axis but we are getting an image that is recognizable. But about 1/4 way through the drawing the laser motion comes to a crawl.

    Is there something else that we didn't think about in the Trajectory settings which was causing the C Axis to drive very slow during coordinated motion?

    There will be a video headed your way when we finally get this ting working.
    Thanks Again
    Dan



  3. #23
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    Default Re: Laser Engraver DAC settings not fast enough

    Here is a test I made up for the attached image.

    Attached Files Attached Files


  4. #24
    Member TomKerekes's Avatar
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    Default Re: Laser Engraver DAC settings not fast enough

    Hi Dan,

    Using Degrees with Zero Radius seems to work correctly for me.

    I Plotted your G Code as C (the desired Laser setting) vs Y Posiion for the first scan line:

    Laser Engraver DAC settings not fast enough-gcode-c-vs-y-png


    I ran the GCode and captured trajectory data in KFLOP for the first scan line. Here is the Y Position vs time. Note Y is at constant speed:

    Laser Engraver DAC settings not fast enough-y-position-vs-time-png


    Here is the C Position vs Time:

    Laser Engraver DAC settings not fast enough-c-position-vs-time-png



    Here is the Kanalog DAC Output captured on a Scope

    Laser Engraver DAC settings not fast enough-dac_voltage-png



    Here is the Trajectory Planner Settings that I used:
    Laser Engraver DAC settings not fast enough-tp_settings-jpg



    Here are the Configuration settings used for the C Axis
    Laser Engraver DAC settings not fast enough-config_settings-png



    Here are the Step Response settings used for the C Axis
    Laser Engraver DAC settings not fast enough-step_settings-png

    HTH
    Regards

    Regards
    TK http://dynomotion.com


  5. #25
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    Default Re: Laser Engraver DAC settings not fast enough

    Hi Tom, thanks for the help so far!

    We updated all of the applicable fields to match what you had. the only thing i left was the Max Limits in Step response has to be left at 1024 because my Laser driver can only accept a 5V in put from the DAC.and Cnts/deg for C is still 1024. This was when C=1 we get a 5V signal.

    We ran into the same issue we had before. With Radius Inches (Trajectory Planner Menu) set to 0, the X and Y were smooth from feed rate to zero and back. But the laser wasn't fluctuating properly though the C readout seemed to be moving it up and down as it was supposed to. The Analog screen in Kmotion wasn't moving as fast either as when radius inch was set to 01.

    When i changed the Radius Inches to 0.1 the laser would power up and down fast like it was getting the rapid response from the DAC but it wasn't a perfectly smooth motion in the Y direction it woudl slow down or hesitate on it's way to the feedrate value..

    I've attached the current screen shots and updated initialization file based on your recommendations. It's getting better but it's not there yet.

    Thanks,
    Dan

    Attached Files Attached Files


  6. #26
    Member TomKerekes's Avatar
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    Default Re: Laser Engraver DAC settings not fast enough

    Hi Dan,

    It doesn't look like you are using the latest Test Version 4.34h. Please try that as there have been some mixed linear/angular feed rate issues fixed. I didn't think they would affect your situation but it appears they do.

    Regards

    Regards
    TK http://dynomotion.com


  7. #27
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    Default Re: Laser Engraver DAC settings not fast enough

    Quote Originally Posted by TomKerekes View Post
    Hi Dan,

    It doesn't look like you are using the latest Test Version 4.34h. Please try that as there have been some mixed linear/angular feed rate issues fixed. I didn't think they would affect your situation but it appears they do.

    Regards
    SUCCESS!!!!!!!

    It's finally running like it is supposed to.

    Now we have to learn the laser programming software and will make a video of it once we know what we are doing.

    Thanks for the awesome support Tom.

    -Dan



  8. #28
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    Default Re: Laser Engraver DAC settings not fast enough

    Hey Tom,

    It's been a long road but it think we are getting somewhere.

    Take a look...





  9. #29
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    Default Re: Laser Engraver DAC settings not fast enough

    So cool

    Regards
    TK http://dynomotion.com


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Laser Engraver DAC settings not fast enough

Laser Engraver DAC settings not fast enough