Re: Digitizers, Renishaw

Gordon,

I would think the "star" has an insulating layer (pcb), with the "tips"
of the star metal for contacts. The three "pairs" of balls are wired in
series. That should do it, but 6 4mm balls on a 30mm ring circle don't
have 2mm spacing (is my math ok?), so we'll have to work on that. a foam
"spring" (non conductive) presses on the top of the star.

Patented? Probably so. But as I understand it, we can make a model of
it for our own use. We just couldn't SELL them without a license
(someone can correct me if I'm wrong).

This would be good for the "auto origin" hardware we were talking about
also!

DEFIANTLY not 1000's of $$ to make!

Alan KM6VV

Smoke wrote:

>
> The only thing I can't visualize from the description Peter provided, is how
> the actual electrical circuit is constructed.
>
> A skecth would be real helpful here. I think this system could be built for
> a whole lot less than $1000. Is it patented?
>
> Smoke
>
> >That's just the kind of information we're looking for! And it doesn't
> >sound too hard to make! It would be useful to get a better idea what
> >the "star" looks like, but I just drew the balls and star up in Vector,
> >and with a few tries, we should be able to get a star that works (good
> >contact angles). Pictures would help! Do you have any? Also, do you
> >have a URL for CNCDIGIT?
> >
> >Thanks for the contribution!
> >
> >Alan KM6VV
> >
> >
> >
> >PMeinhard@... wrote:
> >>
> >> Hi
> >> I´m digitizing on a little stepper-driven mill using a Renishaw. (got a
> >> broken one from the company I worke for and repaird it). The innerparts a
> >> quite simple and there ist no need for high accuracy . So I think it´s no
> big
> >> thing to built one. Basic thing: The Probing Arm has to be able to move
> in
> >> every direction to avoid breaking . They manage it that way: 6 little
> >> Steel-ball (4mm) are fixed in a circle of 30mm diameter. always two with
> gap
> >> of 2mm between them , half buried in electric isolating material. on
> them
> >> lies a 3-arm-Star of 4mm matrial making an electrical connection while it
> is
> >> pressed with a soft spring on them . This is now forming an electrical
> >> circuit . Lifting an arm of the star would break the circuit. In the
> center
> >> of the star ist an arm leading straight down through a much bigger hole
> in
> >> the center of the isolating material ,60mm long with a little ball on
> the
> >> end. The star is always centering itself, drawing the ball in each
> direktion
> >> makes one star-arm lift off the balls and breaking the circuit. And that
> >> simple thing costs about 1000$- 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
> >
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