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How to Make Splines
Creo Parametric 2.0
S.F DunkerJuly 18, 2013
The existing component was modified to have a root diameter of 1.418
Figure 1
Create a csys where xand yare used to create the involute curve and zis the axis of the shaft. The
sketching plane will be on the end of the shaft.
Figure 2
Create four circles for the outside, pitch, basic, and root diameters. Previous features were suppressed for
clarity.
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Figure 3
Create the involute curve by equation by entering the following equations where ris the radius of the base
diameter. Select the csys created in Figure 2.
Figure 4
The involute curve is shown in Figure 5. It starts from the intersection of the base diameter and top
datum plane.
r = 1.446/2
ang = t * 90
s = (PI * r * t)/2
xc = r * cos(ang)
yc = r * sin(ang)
x = xc + (s * sin(ang))y = yc - (s * cos(ang))
z = 0
OD = 1.550
RD = 1.418 min
BD = 1.446
PD = 1.500
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Figure 5
Create a set of datum points, one at the intersection of the involute curve and the pitch diameter, the other
one at the csys. Connect the two points with a datum curve.
Figure 6
Measure the angle between the curve created in Figure 6 and the top datum plane. The angle is 0.433783
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Figure 7
Sketch two datum points on the spline_sketch_dtm and pitch diameter to represent the thickness of a
single gear tooth. The average tooth thickness, (0.0768 + 0.0755)/2 = 0.07615, was used.
Figure 8
Sketch one curve between PNT3 (tooth pitch point) and the csys, then sketch another curve 0.433783 off
the first curve, intersecting the pitch diameter and the csys.
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Figure 11
Copy the involute curve, then paste special. Apply move/rotate transformation to copies. Pick the z axis
and enter 86.6563. Figure 16 is the result.
Figure 12: Copy
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Figure 13: Paste Special
Figure 14: Apply Move/Rotate
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Figure 15: Rotate/Z Axis Selection
Figure 16: Rotated Involute
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Zoom in and confirm that the rotated involute passes through PNT3 and starts from the base diameter
Figure 17
Mirror the rotated involute about the front plane.
Figure 18
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The involute curves are symmetrical about the front plane. This is required according to the drawing.
Figure 19
Sketch the tooth using pick edge and use tangent constraints.
Figure 20
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Extrude the tooth.
Figure 21
Add chamfers and radii, and then group all features for the tooth.
Figure 22
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Pattern the group according to Figure 23. Divide 360 by the number of teeth: 360/30 = 12. This is the
angle between teeth centers.
Figure 23
Splines should look like Figure 24.
Figure 24
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Create cut for other chamfer and radius.
Figure 25
Finished product.
Figure 26
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Top and bottom teeth are symmetrical about the front plane, according to drawing section a-a.
Figure 27