Re: [CAD_CAM_EDM_DRO] Re: Digitizers, Renishaw

Hi
I´m digitizing on a little stepper-driven mill using a Renishaw. (got a
broken one from the company I worke for and repaird it). The innerparts a
quite simple and there ist no need for high accuracy . So I think it´s no big
thing to built one. Basic thing: The Probing Arm has to be able to move in
every direction to avoid breaking . They manage it that way: 6 little
Steel-ball (4mm) are fixed in a circle of 30mm diameter. always two with gap
of 2mm between them , half buried in electric isolating material. on them
lies a 3-arm-Star of 4mm matrial making an electrical connection while it is
pressed with a soft spring on them . This is now forming an electrical
circuit . Lifting an arm of the star would break the circuit. In the center
of the star ist an arm leading straight down through a much bigger hole in
the center of the isolating material ,60mm long with a little ball on the
end. The star is always centering itself, drawing the ball in each direktion
makes one star-arm lift off the balls and breaking the circuit. And that
simple thing costs about 1000$- but the idea is great.
The accuracy is about 0.005 mm.
( the dimensions are as kept them in my mind and might vary a little)
The Software I use is simple but good, CNCDIGIT. cost about 150$( as far as I
remember) remeber
Regards
Peter