where can i get standard dimensions of components for designing?

to start any designing , standard dimensions are needed, where can i get these dimensions to start designing ?

2 Answers

The word "DESIGN" means a lot... The dimensions which we see as standard dimensions are obtained through a lot of calculations.. e.g. If you want to design a gear for particular conditions.. say for some force and with a certain material... the a design engineer does some calculations regarding beam strength etc. to find the necessary dimensions of gears (like module, no. of teeth).
Then after getting the dimensions we start modelling.