Re: [CAD_CAM_EDM_DRO] Renishaw, digitizers

>
> In a message dated 1/11/01 7:48:28 PM Hawaiian Standard Time,
> jmelson@... writes:
>
> << 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 >>
> Group,
>
> I designed a version that uses a ball from a heim joint. About a 3/8" unit
> would be good . The probe shank is pressed into the center of the ball. I
> have a cylindrical housing that has a delrin bottom plate. Into this, I would
> have three setscrews set so the probe runs deads true by spinning with a dial
> indicator, The three screws would then be locked and connected to a 3 input
> "and" circuit. The trick is to make the fit of the ball to the cylinder bore
> about .0005 clearance. A light spring would press the ball/probe down from
> above. I checked the quality of several ball joint balls and they do vary.
> You must get one of aircraft quality if possible. They have much better
> roundness and squareness of the face to bore. This design may need to be
> sealed to work properly, a tiny bit of grit will make it unreliable.
>
> I will post a drawing if there is interest.
>
> Peter
> THRD, Inc.