Calculating steps per inch - what's wrong with my math??


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Thread: Calculating steps per inch - what's wrong with my math??

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    Default Calculating steps per inch - what's wrong with my math??

    I'm using ClearPath Nema 34 servos with the input resolution set at 6400. They are connected to CNC Router Parts Nema 34 Pro drives at a 3.2:1 ratio.

    My math...

    3.14159 / 3.2 = 0.9817

    6400 / .9817 = 6519.3032 steps per inch.

    But that isn't correct, it's way off.

    Just playing around with numbers in Mach3, it should be closer to 6590.

    What the heck am I doing wrong???

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    I’m on my cell so this might not be wel thought out. In any event the first thing that comes to mind is that that drive is really a gear box and that you are most likely using it in a reduction mode. If that is correct then you need to make 3.2 revolutions of the motor to get one rev off the gear box output shaft. That is 20,480 counts.

    The trouble is this isn’t your counts per inch. To do that you would need to know what the lead of the lead screw is or the ratio to the rack. You don’t have the information needed for a complete answer.

    Quote Originally Posted by bobmagnuson View Post
    I'm using ClearPath Nema 34 servos with the input resolution set at 6400. They are connected to CNC Router Parts Nema 34 Pro drives at a 3.2:1 ratio.

    My math...

    3.14159 / 3.2 = 0.9817

    6400 / .9817 = 6519.3032 steps per inch.

    But that isn't correct, it's way off.

    Just playing around with numbers in Mach3, it should be closer to 6590.

    What the heck am I doing wrong???
    I really don’t know. At this point we need more information to get anywhere.



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    Default Re: Calculating steps per inch - what's wrong with my math??

    Here's what I get:

    Attached Thumbnails Attached Thumbnails Calculating steps per inch - what's wrong with my math??-cncrp-cp-eln-rez-jpg  
    Gary Campbell GCnC Control
    Servo Control & ATC Retrofits


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    Quote Originally Posted by wizard View Post
    I’m on my cell so this might not be wel thought out. In any event the first thing that comes to mind is that that drive is really a gear box and that you are most likely using it in a reduction mode. If that is correct then you need to make 3.2 revolutions of the motor to get one rev off the gear box output shaft. That is 20,480 counts.

    The trouble is this isn’t your counts per inch. To do that you would need to know what the lead of the lead screw is or the ratio to the rack. You don’t have the information needed for a complete answer.



    I really don’t know. At this point we need more information to get anywhere.

    Its running on a 20 pitch, 20 degree pressure angle rack.

    Not sure what else you'd need.

    - - - Updated - - -

    Quote Originally Posted by islaww View Post
    Here's what I get:
    That's basically what I came up with. But it's not right.



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    Default Re: Calculating steps per inch - what's wrong with my math??

    How are you determining that the steps per you calculated is incorrect?

    Ben


    Sent from my E6810 using Tapatalk



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    Default Re: Calculating steps per inch - what's wrong with my math??

    Oh yeah you all have the same and correct steps per for the counts. The 1 count difference is just a rounding error because you used different methods to get to the same place. Wizard just missed the 1 inch pitch diameter and didn't use that info to divide his answer by 3.14159.

    Ben

    Sent from my E6810 using Tapatalk



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Calculating steps per inch - what's wrong with my math??

Calculating steps per inch - what's wrong with my math??