Re: [CAD_CAM_EDM_DRO] Renishaw, digitizers

Bill Phillips wrote:

> Jon Anderson wrote
>
> >3 conical depressions (like a countersink) would work as well, and might
> >be a lot easier to make and be sure they were on target. In fact, you
> >don't even need cones! 3 holes with well-chosen diameters so that they
> >sat part way down on the balls would work quite well.
> >
> >Jon
>
> If you have 3 holes how do you guarantee that each ball will sit down in
> exactly the same place each time? It will be much better to just mill slots
> rather than a holes. The slot will guarantee two points of contact for each
> ball. The six points of contact wil then fix the dangly bit repeatably in 3
> dimensions.

You, this makes a lot of sense! Maybe the slots should be fairly wide, so
that the contact points are not right at the top of the ball, but a good way
down the sides. The pressure of the small contact points would improve
the reliability of the contacts.

Jon