How to create involute gear
How to create involute gear
(OP)
Hello everyone.
I have faced problem with create involute gear in NX. First of all in Cartesian coordinates the involute of a circle has the parametric equation:
In NX there is law curve -> law by equation but when I put this two equation I get line. What I do wrong?
I also found this manual:
Link
but when I create gear with small numbers of teeth the shape of teeth doesn't match shape of co-working gear. In attachment I put my gear with imported geometry from Hasco to show problem. Anyone have forced similar problem and can help me?
I have faced problem with create involute gear in NX. First of all in Cartesian coordinates the involute of a circle has the parametric equation:
CODE
x=r*(cosΘ+ΘsinΘ) y=r*(sinΘ-ΘcosΘ)
I also found this manual:
Link
but when I create gear with small numbers of teeth the shape of teeth doesn't match shape of co-working gear. In attachment I put my gear with imported geometry from Hasco to show problem. Anyone have forced similar problem and can help me?
With best regards
Michael





RE: How to create involute gear
Link
RE: How to create involute gear
xt=function(t)
RE: How to create involute gear
CODE
CODE
but I get line. Please look at the attached pictures.
Link
Link
The main problem is, when I create gear with small no of tooth for example z=20, there are some differences between my model and imported geometry from hasco. There are also collisions with co-working gear. Do You remember which function You used to create law curve?
With best regards
Michael
RE: How to create involute gear
See:
https://en.wikipedia.org/wiki/Gear#Tooth_profile
and also page 5 of the following pdf
http://www.bostongear.com/pdf/gear_theory.pdf
www.nxjournaling.com
RE: How to create involute gear
John R. Baker, P.E.
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To an Engineer, the glass is twice as big as it needs to be.
RE: How to create involute gear
I had taught that
CODE
With best regards
Michael
RE: How to create involute gear
With best regards
Michael
RE: How to create involute gear
RE: How to create involute gear
RE: How to create involute gear
And here - correct involute curve, 10 turns.
Be happy!
RE: How to create involute gear
With best regards
Michael
RE: How to create involute gear
Part of that program is a function that calculates a point on an involute curve, as follows:
CODE --> VB
' Calculates positions on a segment of an involute curve Private Shared Function InvoluteFunction(data As Object, u As Double) As Position ' Note that the involute curve here is parameterised by radial distance from the origin (r). ' The more common approach is to parameterise by angle (theta) but this causes a ' singularity at the start point (derivative vector has zero length), which leads ' to a nasty Bezier curve whose first and second poles coincide. Dim params As Double() = CType(data, Double()) Dim a = params(0) ' Radius of base circle of involute Dim r0 = params(1) ' Radial parameter value at start point of involute segment Dim r1 = params(2) ' Radial parameter value at end point of involute segment Dim r = r0 + u * (r1 - r0) Dim theta As Double = System.Math.Sqrt(r*r - a*a)/a Dim x As Double = a * ( System.Math.Cos(theta) + theta * System.Math.Sin(theta) ) Dim y As Double = a * ( System.Math.Sin(theta) - theta * System.Math.Cos(theta) ) return new Position(x, y, 0) End FunctionIn some cases, the involute curve is extended with a straight line. This might be related to the "undercut" idea mentioned in cowski's answer