Re: [CAD_CAM_EDM_DRO] 12 teeth 48 pitch gear

----- Original Message -----
From: <cadcamcenter@...>

> "The motor shaft has a 48 pitch gear attached. The gear has 12 teeth"
>
> >From this, is it possible to figure the outside/inside diameter or
> both?

Your gear is 48 diametral pitch. Diametral pitch is defined as the total
number of teeth divided by the pitch diameter. The pitch diameter occurs at
the circle of contact with a mating gear, approximately half way between the
root and crest of the tooth.

If you divide the number of teeth by the diametral pitch you get the pitch
diameter. Thus 12/48 = .25 dia.

Note that diametral pitch is a function of diameter and not circumfrence.
Therefore the rack will have 48 teeth per 3.14 inches of length. The 12
tooth gear will advance .25pi per revolution or .7854 inch.

> If I am to look for a rack or geared wheel to mesh with this 48 pitch
> gear, what do I have to look for/specify?

The rack must also be 48 pitch.

You can take out backlash in several ways. The easiest would be to
over-mesh the gears. They are designed for running clearance - hence
backlash - when the pitch circles are tangent to each other. Push them
together a little more and you will get an interference fit. The purist
might argue that this is bad practice because it upsets the pressure angle
relationship and leads to excessive wear. This is true, but for a machine
that is made of used parts it is perfectly acceptable.

Doug