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baronep
01-04-2012, 09:04 PM
How does one cad spur gears in solidworks? And how would they be manufactured?

Cory
01-04-2012, 09:11 PM
Don't. Download them from McMaster, SDP, etc.

They are manufactured in a number of ways. Most common would be hobbing and shaping.

Tristan Lall
01-04-2012, 09:13 PM
Are you looking to model the gear exactly, or roughly for basic design work? (If exactly, see below; if roughly, use a cylinder the size of the pitch diameter.)

And will you be manufacturing gears yourself, or are you just wondering how gears are made industrially? (Either way, some ideas and references are presented below. The usual mass-production way is hobbing (http://en.wikipedia.org/wiki/Hobbing), but many other methods exist.)

Lots of existing threads on these topics exist (often with links to external tutorials). Some examples:
Where to find gear 3d models? (http://www.chiefdelphi.com/forums/showthread.php?t=99117)
Lasercutting Spur Gears? (http://www.chiefdelphi.com/forums/showthread.php?t=27622)
32DP 19T 20PA Pinion Wire (http://www.chiefdelphi.com/forums/showthread.php?t=38417)

Frenchie461
01-05-2012, 04:24 PM
If you aren't planning on rendering the gear for any reason, just use a cylinder (i.e a 20 tooth 20 dp gear .4 inches thick becomes a 1 inch diameter by .4 inch high cylinder).

If you are planning on rendering then download the models from here (http://team1323.com/cad/pages/gears.html)

s_forbes
01-05-2012, 04:41 PM
It's usually much easier to buy gears than it is to manufacture your own. Some sites like McMaster Carr have CAD models of the parts they sell, so there is no need to create your own model.

If you need to create a gear in Solidworks that you can't find a model for, the Toolbox works very well. In an assembly you can insert a part that has the desired number of teeth and diametrical pitch, then edit it if necessary.

Ian Curtis
01-05-2012, 05:11 PM
If you are interested in the math behind an involute gear and how to sketch one, this online tutorial (http://www.cartertools.com/involute.html) is a good one to follow.

If you want to draw gears to design and build crazy mechanisms and cut them yourself (you'll want a CNC machine), the guy responsible for Mach3 has been developing Gearotic Motion (http://gearotic.com/), which is a pretty incredible tool. It is free to download and play with, and only $75 if you want to be able to export the gears.

kinghashbrown
01-11-2012, 11:05 AM
I use toolbox for gears. It's also good for sprockets and bolts.

junefish
01-22-2012, 09:08 PM
I definitely agree that you should either download the CAD file from McMaster-Carr (et cetera) or utilise the Toolbox. If not, a "simple" CAD will suffice--i.e., a cylinder. If you actually want to CAD the gear, however, I believe that you attach half an ellipse to a circle & use a Rotational Sketch Pattern to surround the rest of the circle.

wireties
01-22-2012, 09:19 PM
FIRST Team 1296 borrowed a technique from the robo-wranglers. We make exotic-shaped aluminum gears from sheet metal and rivet them together to get the desired width. They would not last long enough in an industrial setting but on a FIRST robot, they are good enough. It works for us since we have an awesome sheet metal company as a sponsor.

HTH

Exla357
02-14-2012, 05:50 PM
There is a simple way to do it on Solidworks 2009, but it takes a lot of time because gear mates have to be made for each "tooth"

Make a cylinder, on say the Top Plane. Now, create a new sketch on the same plane as a point for the extruded cut that will be the airspace between the gears (if that makes any sense). Now, make the extruded cut. In features, select the pattern tab and choose "Circular Pattern." Select the extruded cut, check "Equal Spacing." For Parameters, select one of the edges of the circle. Now, increase the number of features until you get what you like, than accept.

Hope that made sense.

-Alex