Re: Does anyone know of some cheap gear designsoftware ?

> Hi again John:
>
> You could be correct as to the accuracy <or lack of...> of the
>above link,
> I don't know.
>
> However regarding a 14.5 PA (pressure angle) gear of 12 teeth,
>
> Machinists handbook 23 (page 1772) says the MINIMUM number of teeth
> for these pressure angles should be:
>
> 20 degree PA - minimum teeth 18
> 25 degree PA - minimum teeth 12
>
> By extrapolation then, a 14.5 PA angle gear should have more than
>18
> teeth (ie a 14.5PA gear of 12 teeth is undefined and so using it
>for
> an example/counterexample is not relevant). In any case, for small
> gears you probably want to be hobbing them (a valid cnc
>operation!),
> otherwise the required mill bit dia would be exceedingly small!
>
> Anyway to bring it back 'on topic', I found geargen 1.1 at this
>site:
>
> http://www.bookcase.com/library/software/msdos . desktop . cad .
>html
>
> and I'll give it a try as you suggest.
>
> cheers
> Doug Fortune
> http://www.cncKITS.com

Doug, It's just a good guide to choose a low numder of teeth such as
this to see if the undercutting is present to give you a quick idea
if they are obeying the true definition of involute.
Many CAD programs only draw a rough shape.
If this is deamed off list we can take this over to the DIY - CNC
group at http://groups.yahoo.com/group/DIY-CNC/

John S.