Re: [CAD_CAM_EDM_DRO] Re: Digitizers, Renishaw

I think technically you can't "legally" make them for your own use if they
are patented. One of you leagl begals can correct me if I'm wrong.

I'll have to check on the math...maybe tomorrow when I get some time. Right
now it's time to take a break!

I'd still like to see a diagram showing how those balls are connected into
the electric circuit.

Smoke
-----Original Message-----
From: Alan Marconett KM6VV <KM6VV@...>
To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
Date: Thursday, January 04, 2001 5:49 PM
Subject: [CAD_CAM_EDM_DRO] 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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