View Full Version : This Type Of Gears
11-08-2007, 07:14 AM
This was asked over on the Autodesk Forums,
thought I'd see what the NURBS pros here think. How would you model this set of gears?
11-08-2007, 07:48 AM
Create the basic shape outline and revolve it. Make sure the outline includes the top area of the gear teeth. Then make a solid/extruded shape similar to the recessed area of the gear teeth. Create a rotational array to distribute them around the model. Pwr_Boolean subtract the recessed area from the original revolve object. Should be pretty simple.
11-08-2007, 10:11 AM
I've got a rough model of the bottom gear (but as before still not the same as the picture) but have to figure out the formula to match it up with the top gear.
What I seem to be missing is the right shape for the boolean-ing of the space between the gear teeth. I tried to create a profile and then a larger profile and blend them but the ends wouldn't close. All I have here is a triangular shape extruded, so it creates a pie shape that leaves the gear teeth as the bottom of the model thicker than at the top which is incorrect.
11-08-2007, 10:38 AM
11-08-2007, 11:12 AM
Create the shape you want for the gear teeth. Now before extruding create the circular array of shapes. Duplicate these wedges and hide them for now. Now create 2 Circles larger than the area you will be booleaning. Collapse one Circle to an Edit_Sketch and attach the other one. With the Circles selected select 2D_Boolean. Start picking one set of wedges. You should end up with a 2D object that is an opposite match to the teeth shape.
With solids modeling you need to kind of think outside the box. Its solids you will be booleaning to add or remove from the initial shape.
11-08-2007, 11:20 AM
You could also do the same thing with a tube shape and the teeth shape. This way you can make the angular shape you need and then Boolean or Cutter the object to get the shape(s) you need.
11-08-2007, 11:39 AM
I get the principle Eric though I'd have to actually run through it to solidify it.
I don't think you addressed the shape I need for the teeth initially. I have a "wedge" but it's not correct.
11-08-2007, 02:13 PM
George Vitetta taught me another method that would work for this type of model. What he does is create the curves for a single gear tooth. Then he array copies it around a circle (setting a rotation point in the middle). Then he uses the rail sweep tool (or blend) to connect it all up. He was going to do a little video tutorial of this technique, but I don't think he has had time.
11-11-2007, 02:26 AM
I'd be interested in seeing the video.
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