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    Default Spindle

    Just installed 18,000 rpm spindle. Works using kmoton buttons cw,ccw and stop. Also if I run it at 20% the rpm is 3600 using a laser tach so that's good.
    Question:

    1 Want to set it up as an axis, it is open loop, manual says it can be done,do I need to put some thing in the in I file to identify it as an axis? And what would I add, I have it on dac 7, controlling delta vfd at 10 volts = -2047 all good. Do I need to add something to the in I file so the machine knows I want it be an axis, what should I add.

    2 in kmotion next to the red s it says 1000 shouldn't that say 18,000?

    3 every time I start kmotion the x and y axis say 0 but the z axis says -1 when I initiate why aren't they all 0.

    4 i don't see anywhere in the kmotion screen what rpm the spindle is running only % of speed?

    Joe

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    Default Re: Spindle

    Some details about the spindle, and how it's being controlled by the KFlop would be good...



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    Quote Originally Posted by m_c View Post
    Some details about the spindle, and how it's being controlled by the KFlop would be good...
    I am controlling two i/o bits that control 2 relays one for cw and one for ccw. They are outputs from a kanalog board. The relays close contacts for cw and ccw on a delta vfd.

    I am controlling speed from a kanalog DAC directly to the delta vfd.

    I followed the instructions for basic configuration in the spindle control manual

    Last edited by mirocha; 12-15-2017 at 06:03 PM.


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    Quote Originally Posted by m_c View Post
    Some details about the spindle, and how it's being controlled by the KFlop would be good...
    I am controlling two i/o bits that control 2 relays one for cw and one for ccw. They are outputs from a kanalog board. The relays close contacts for cw and ccw on a delta vfd.

    I am controlling speed from a kanalog DAC directly to the delta vfd. I can change the speed on the kmotion slider by percentage.

    I followed the instructions for basic configuration in the kmotioncnc spindle control manual directions.

    I set it up in the tool setup screen in kmotion.

    And it works to run the spindle and change speed but how do you have kmotion know what the rpm of the spindle is not just percentage of an unknown, to kmotion, maximum rpm. how does g code set the rpm, as it is now kmotion controls speed by a percentage but I don't see how it knows what the rpm is

    Joe



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    Default Re: Spindle

    I suspected this would be a VFD spindle, in which case there is no way to control it closed loop, unless you add an encoder.

    As for getting KMotionCNC to show the (open loop) speed, you need to alter the C programs you're using to set the speed, so that KMotion knows what the required ratios are to calculate the speed.
    What C programs are you using to set the speed?



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    Quote Originally Posted by m_c View Post
    I suspected this would be a VFD spindle, in which case there is no way to control it closed loop, unless you add an encoder.

    As for getting KMotionCNC to show the (open loop) speed, you need to alter the C programs you're using to set the speed, so that KMotion knows what the required ratios are to calculate the speed.
    What C programs are you using to set the speed?
    I am not using any c program at all for spindle control, yes this is an open loop 3 hp 220 volt 18000 rpm spindle, the kmotion manual has a section on setting up a spindle that uses i/o bits for cw and ccw and using DAC for 10V speed control. It works in kmotion using the jog buttons to start the spindle either cw or ccw and I can use the kmotion slider on the screen to adjust the spindle speed percentage and it works changing the speed of the spindle by percentage. That does not give rpm or tell kmotion any speed ratio.

    That's what I need to know, do I need a c program or add something to ini file. I would hope there's a way to tell kmotion the ratio, I don't see any where kmotion screen shows spindle rpm my screen does have 1000 next to the red s but that does not change when I change the percentage of spindle speed, as I said I can change spindle speed.

    I have my x,y and z axis working now time to get the spindle working.

    Does kmotion normally show spindle rpm some where, I'm new to cnc. Building a cnc router as a retirement project. Almost done just need to get the spindle right.

    Joe



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    Default Re: Spindle

    Hi Joe,

    You aren't being real clear on what you are doing. But I'm guessing you are using the Basic method where no C Programs are required at all. KMotionCNC just scales the RPM the way you specify and commands a DAC as described here:

    KMotionCNC Spindle Control

    In this case you need to calculate the proper scaling for your system. If -2047 DAC counts runs at 18000RPM then the scale factor to enter would be:

    -2047/18000 = -0.11372

    But then you say you would like to control the spindle like an axis. What do you mean by that and why?

    Regards

    Regards
    TK http://dynomotion.com


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    Quote Originally Posted by TomKerekes View Post
    Hi Joe,

    You aren't being real clear on what you are doing. But I'm guessing you are using the Basic method where no C Programs are required at all. KMotionCNC just scales the RPM the way you specify and commands a DAC as described here:

    KMotionCNC Spindle Control

    In this case you need to calculate the proper scaling for your system. If -2047 DAC counts runs at 18000RPM then the scale factor to enter would be:

    -2047/18000 = -0.11372

    But then you say you would like to control the spindle like an axis. What do you mean by that and why?

    Regards
    Yes I am using the basic method, you say to use a scale factor, where do I enter the scale factor?

    In the tool setup screen I set DAC 7 scale -2.047 offset 0 min -2047 max 0 as in the example, the way it is written -2.047 = +10 volts.

    I did check with a laser tech and when the spindle is running if I change the percentage the rpm Is correct, 20 % setting gives me 3600 rpms 50% gives me 9000 rpms so that does work with what I entered.


    Is this where I enter the scale factor of 0.11372 if so what do I set the min value too?

    The manual says for spindles controlled open loop it is possible to configure an axis channel to output current speed directly to a DAC and there are advantages, using jog speed commands and ramp the speed. Also be able to use the configure screen, so I am just thinking that would be a good thing.

    Also what does the 1000 next to the red "S" mean and does kmotion show spindle rpm when the spindle is running or just percentage?

    Thank you for your quick response.

    Joe



    Joe



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    Default Re: Spindle

    Hi Joe,

    Enter the new scale factor after where it says "scale"

    The example assumes a range of 0 - 1000RPM. It isn't a percentage it is RPM. Your machine is 18 times faster so you will need to reduce the scaling by a factor of 18.

    Everything else should remain the same. as you still want an output of 0 to -2047 counts (0 to +10V)

    HTH
    Regards

    Regards
    TK http://dynomotion.com


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    Default

    Quote Originally Posted by TomKerekes View Post
    Hi Joe,

    Enter the new scale factor after where it says "scale"

    The example assumes a range of 0 - 1000RPM. It isn't a percentage it is RPM. Your machine is 18 times faster so you will need to reduce the scaling by a factor of 18.

    Everything else should remain the same. as you still want an output of 0 to -2047 counts (0 to +10V)

    HTH
    Regards
    Did not work, entered scale factor -0.11372, set slider to .1 and .2 in kmotion spindle barely spun, entered .5 in the box and pressed apply and vfd tripped out on error, at .1 or it may have been .2 on the slider, the vfd output was about 37 hz.

    Set the scale back to - 2.047 and spindle ran at 3600 rpm with slider at .2 and at .5 it ran at 9000 rpm. I am checking the actual rpm with a laser tach.

    The DAC output is changing the voltage output to the vfd using a scale factor of -2.047 and is linear with the slider relationship to the motor rpm.

    The number 1000 next to the big red "S" stated at 1000 when I changed the scale number.

    Just for my own knowledge what does that 1000 number represent.

    At this point kmotion does not know I have a 18,000 rpm spindle.

    Joe



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    Default Re: Spindle

    Hi Joe,

    I think you are confusing Spindle RPM set with the S Code with SSO (Spindle Speed Override).

    Try:

    #1 Set scale factor to -0.11372

    #2 Set some Spindle Speed with a GCode S Command. For example: S18000

    #3 With SSO slider at 1.0 the actual Spindle speed should be 18000RPM

    (You might also need to push the Spindle ON button)

    Regards

    Regards
    TK http://dynomotion.com


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    Default

    Quote Originally Posted by TomKerekes View Post
    Hi Joe,

    I think you are confusing Spindle RPM set with the S Code with SSO (Spindle Speed Override).

    Try:

    #1 Set scale factor to -0.11372

    #2 Set some Spindle Speed with a GCode S Command. For example: S18000

    #3 With SSO slider at 1.0 the actual Spindle speed should be 18000RPM

    (You might also need to push the Spindle ON button)

    Regards
    Wow there is nothing wrong, works great and the 1000 now shows the spindle rpm I set in the g code.

    The spindle does run faster than what I ask for, at 3000 the actual rpm was about 3026 and at 9000 rpm it was about 9057, I would think on a open loop spindle that's ok, I don't know any better.

    Thank you so much, it works!

    Joe



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    Default Re: Spindle

    Hi Joe,

    Great. Thanks for posting back.

    You might tweak the scale factor slightly to make it a little better. Try:

    -0.11372 x (9000/9057) = -0.11300

    Regards

    Regards
    TK http://dynomotion.com


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