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How to create spur gear in Siemens NX?

Tutorial by Hegedűs György
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This tutorial presents the modeling of an external spur gear in Siemens NX.
The detailed modeling process is demonstrated on this video:

https://youtu.be/pVPjDyOn6R4

UPDATE: At ~ 2:40 leave the Limit options at default (At Point). See the errata video for the reason:
https://youtu.be/PUpdlyQcaOs

  1. Step 1:

    Copy these parameters into a text file and save it. Rename the file extension to .exp.

    [degrees]alpha=20 //Reference Pressure Angle
    c=sqrt(1/(cos(alpha))^2-1)/pi() //Parameter of Involute Curve
    [mm]m=3.5 //Module
    [degrees]phi=arctan(yc/zc)+90/z //Rotation angle
    [mm]r=m*z/2 //Reference Radius
    [mm]ra=r+m //Tip Radius
    [mm]rb=r*cos(alpha) //Base Radius
    [mm]rc=m*.38 //Tooth Blend Radius
    [mm]rf=if(m>1.25)(r-1.25*m)else(r-1.4*m) //Root Radius
    t=0 //NX Parameter
    [mm]xt=0 //x Coordinates of Involute
    yc=rb*(sin(deg(c*pi()))-cos(deg(c*pi()))*c*pi())
    yt=rb*(sin(deg(t*pi()))-cos(deg(t*pi()))*t*pi()) //y Coordinates of Involute
    (Integer) z=25 //Number of Teeth
    zc=rb*(cos(deg(c*pi()))+sin(deg(c*pi()))*c*pi())
    zt=rb*(cos(deg(t*pi()))+sin(deg(t*pi()))*t*pi()) //z Coordinates of Involute

  2. Step 2:

    Launch NX, create a new model file, push the CTRL+E keys and imports the expressions.

  3. Step 3:

    Create the involute curve by Law Curve command.

  4. Step 4:

    Create a circular pattern on the involute curve.

  5. Step 5:

    Draw a line which starts from the end point of involute and tangents the curve. Set its limit by equation.

  6. Step 6:

    Launch the Join Curve command and join the line and the involute curve.

  7. Step 7:

    Draw the tip and root circles by full circle. Draw a tangent circle for the tooth blend.

  8. Step 8:

    Trim the unnecessary parts of the curves.

  9. Step 9:

    Mirror the involute curve and the tangent circle.

  10. Step 10:

    Trim the tip and root circles.

  11. Step 11:

    Create a circular pattern, set the parameters.

  12. Step 12:

    Extrude the curves to get the spur gear body.

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