Point rotation BUG in the stock SpurGear script/add-in

[Anonymous]

The following code (line 209 in the python script version) is incorrect - I have not checked the JS or Cpp versions but it's likely the bug is there as well.

    # Rotate the involute so the intersection point lies on the x axis.
    cosAngle = math.cos(-pitchPointAngle + (tooththicknessAngle / 2))
    sinAngle = math.sin(-pitchPointAngle + (tooththicknessAngle / 2))
    for i in range(0, involutePointCount):
        involutePoints[i].x = involutePoints[i].x * cosAngle - involutePoints[i].y * sinAngle
        involutePoints[i].y = involutePoints[i].x * sinAngle + involutePoints[i].y * cosAngle

The error is that the point rotation will be skewed because the Y transformation is computed on the already transformed X.

The corrected code follows

    # Rotate the involute so the intersection point lies on the x axis.
    cosAngle = math.cos(-pitchPointAngle + (tooththicknessAngle / 2))
    sinAngle = math.sin(-pitchPointAngle + (tooththicknessAngle / 2))
    for i in range(0, involutePointCount):
        x = involutePoints[i].x
        involutePoints[i].x = x * cosAngle - involutePoints[i].y * sinAngle
        involutePoints[i].y = x * sinAngle + involutePoints[i].y * cosAngle

[ekinsb]

I recently just updated the spur gear program and did find a couple of bugs that I fixed in the process.  I don't remember the details now though of what I fixed.  The new version is coming out in a Fusion 360 update scheduled for next week.

[Anonymous]

This issue (point rotation) looks to be fixed in the updated version, which looks excellent by the way. I haven't had a chance to really test it out yet but the descriptive image caught my eye and i noticed that "Module" is labeled incorrectly - What is labled as "Module" is actually Circular Pitch which is Pi * Module. I'm trying to figure out how to describe module with a graphic myself but it's hard to do without declaring d = m*z (Pitch Diameter = Module * Teeth)

[ekinsb]

The incorrect picture was identified right after the update went out and has been corrected and should be in the update next month.