Re: Making Stepper Pullys

>--- In CAD_CAM_EDM_DRO@y..., "Ian Wright" <Ian@i...> wrote:
> HI John,
>
> It can be even easier than this - I 'reverse engineered' a couple
>of small
> pulleys I bought (yes I know its not a word usually associated with
>me <G>)
> from HPC Gears in Chesterfield - 2.5 mm pitch - and found that they
>simply
> use a circle of drilled holes and then machine just over half away
>and round
> off the edges - probably by tumbling. When you think about it, if
>you cut
> away the right amount of the holes you can get the angle of the
>sides pretty
> close to ideal.

Ian,
Yes this is one way but Bill is refering to standard type of timing
belt with the trapieziod form, you are refering to the HTD which have
a totally different tooth form.
Unlike a gear where the OD is greater than the PCD on a timing belt
pulley it's reversed. The OD is smaller than the PCD, the belt
actually 'lays' on top of the OD.

John S.

PS. The HTD type are still produced with hobbing cutters and not
drilled holes.