extension rail track pitch????

[eddie]

hello all,

i am building an extension rail for my 11x14 empire state.

how do i measure the track for the correct pitch? where do i get tracks of the right pitch?

thanks
eddie

[John Schneider]

The pitch is the number of teeth per inch, and you can buy gear racks from McMaster:
http://www.mcmaster.com/#catalog/115/1052/=uywmm
There are a number of other considerations, like gear pressure angle that probably won't matter too much for your application.

[eddie]

but what about the pitch of the teeth? is it all the same?

[erie patsellis]

Gearing is typically measured in diametrical pitch. if you google stock drive products, they have an enormous amount of information on their website that will answer your questions (and some you haven't thought of yet!)