When you start Solidworks and choose "click new document " in the "file" command, you may choose the following three modes.
1) Part, 2) Assembly, 3) Drawing
And as I stated in the last blog (Solidworks, actual operating environment on a low budget)" modeling" is different from "design."
If you start a machine design, to meet the offer requirement you may create a new part by diverting an existing part. Or, may use it in case of tight delivery date, or when you already purchase the part on the market and use it.
Both the cost and the delivery time are almost determined in design. Of course, depends on manufacturing staff, assembly team and designer's skill, to do the design, and deliver a high-quality product.
There is never enough time to do a design, even if you design all parts from the beginning every time. And there will always be problems, time loss, and human mistakes.
You can use a maker part which makes mainly the "gear" part if it meets specifications. In this situation, the simple design tool in the toolbox is convenient with the assembly mode of SolidWorks.
It is very hard to draw from the beginning and to model a helical gear. But you can make a model with the simple design tool if you have the necessary parameters such as the number of teeth, and helical angle. However, it will be different from a real gear product because it is just a simple design tool. (Inventor has a similar function as the design tool)
Watch it in Youtube by accessing the link below.