Helical Gear or Angled Spur Gear?

[CS5050]

This may seem like a concerning question, but I am going to ask it anyways.

Is there such a gear as a spur gear simply cut on an angle?

We are researching the use of helical gear application, but there is some debate about how to model a gear, properly.
I have drafted a sketch (involute) in the center of a cylinder and lofted the cut on the angle desired in each direction to create a tooth profile. My colleague has done something similar the but the sketch is drawn on a plane angled and cut directly on this angle.

Mine results in a helix, his results in a tooth profile cut directly on that angle.

Looking at physical gears on site, under magnification, it appears that a gear we have in hand is has the profile cut directly on an angle, rather then in a loft (creating a helix). But my research has only found gears in depicted with a helix, so I wonder about this gear?

thanks!

 

[SwinnyGG]

The helix angle of the gear you have in hand might be very shallow which makes it appear to have a non-helical cutting pat.

Cutting a gear tooth by moving the cutting tool in a straight line which is not parallel to the gear axis would result in gear teeth which have non-uniform depth and thickness. It would also be more difficult than hobbing, how gears are usually made.

 

[spigor]

The involute profile must be drawn on a right section (transverse) plane

https://www.youtube.com/watch?v=XJ2nAUeiCHM

The gear's parameters are given in the normal plane, so first you need to calculate these parameters in the transverse plane, draw the involute profile in the transverse plane and make a helical extrusion. The formulas for the parameters in the transverse plane can be found here:

https://books.google.pl/books?id=ko...AQ#v=onepage&q=gear transverse module&f=false

Good luck!