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Elliptical Gears on Solid Works
- Thread starter Kriegen
- Start date
CorBlimeyLimey
Mechanical
![[cheers]](/data/assets/smilies/cheers.gif "[cheers] [cheers]")
Gear trax is great for making gears. Only thing i can think of for making gears like that would be to use a curve driven pattern to control the teeth around the elliptical body.
Regards,
Scott Baugh, CSWP![[pc2]](/data/assets/smilies/pc2.gif "[pc2] [pc2]")
faq731-376
Regards,
Scott Baugh, CSWP
faq731-376
FooFire,
1st order, [basic true ellipse], 2nd order? with basic, with 2nd order, with 3rd order, 4th order? combination of what with what?
Basic ellipses, must have same N.O.T. (twins) & should be odd N.O.T. and must rotate about their focal points.
The simplest to manufacture, therefor to model?
2nd & subsequent orders may rotate about center of the shape.
Sketch in centerline of each tooth space, calculate the different shape of each valley at that point, useing the pitch radius at that space to establish the equivalent Gear space form.
Therefor if your ellipse has 35 teeth you will have to calculate 35 tooth spaces & Cut each tooth space independantly. (Tip) a 3 point arc constructed with points at the OD, PD and base dia or root dia will have an error of less than .0005" on the involute form, two arcs contructed from 5 points, 1,2,3 & 3,4,5 will have less than .0002" error of form, the error takes on an "S" shape or stacked double "S".
The shaper machines used cams or later on, CNC to cut these gears.
Then comes the higher orders now it becomes fun, but should be do-able.
Cheers Les H.
1st order, [basic true ellipse], 2nd order? with basic, with 2nd order, with 3rd order, 4th order? combination of what with what?
Basic ellipses, must have same N.O.T. (twins) & should be odd N.O.T. and must rotate about their focal points.
The simplest to manufacture, therefor to model?
2nd & subsequent orders may rotate about center of the shape.
Sketch in centerline of each tooth space, calculate the different shape of each valley at that point, useing the pitch radius at that space to establish the equivalent Gear space form.
Therefor if your ellipse has 35 teeth you will have to calculate 35 tooth spaces & Cut each tooth space independantly. (Tip) a 3 point arc constructed with points at the OD, PD and base dia or root dia will have an error of less than .0005" on the involute form, two arcs contructed from 5 points, 1,2,3 & 3,4,5 will have less than .0002" error of form, the error takes on an "S" shape or stacked double "S".
The shaper machines used cams or later on, CNC to cut these gears.
Then comes the higher orders now it becomes fun, but should be do-able.
Cheers Les H.
Hi,
I hope, you realize that not only all the teeth in one quadrant are different, but each tooth has different flanks. I once wrote a VBA program for this, however, it's not ready for prime time. It puts out a polyline for AutoCad that, I am pretty sure, can be turned into an extrusion by almost any program.
I will not release this thing to the public, but if you want, let me have your data and I'll send you the result. Keep in mind, however, that it is written to accept diametral pitch and, therefore, does not allow you to e.g. specify elliptical axis it will, however, let you define the ratio of the two axis and the number of teeth.
P.S. Not quite true: they are a bunch of lines representing a single tooth of a rack that I rotated around the ellipse, but they can be easily connected to form points or polylines. The reason why I didn't just draw involutes is, I couldn't figure out how to do this with the curvature of the ellipse constantly changing.
I hope, you realize that not only all the teeth in one quadrant are different, but each tooth has different flanks. I once wrote a VBA program for this, however, it's not ready for prime time. It puts out a polyline for AutoCad that, I am pretty sure, can be turned into an extrusion by almost any program.
I will not release this thing to the public, but if you want, let me have your data and I'll send you the result. Keep in mind, however, that it is written to accept diametral pitch and, therefore, does not allow you to e.g. specify elliptical axis it will, however, let you define the ratio of the two axis and the number of teeth.
P.S. Not quite true: they are a bunch of lines representing a single tooth of a rack that I rotated around the ellipse, but they can be easily connected to form points or polylines. The reason why I didn't just draw involutes is, I couldn't figure out how to do this with the curvature of the ellipse constantly changing.
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