Re: [CAD_CAM_EDM_DRO] Re: Digitizers, Renishaw

Just musing...or more like a wierd daydream just went flitting thru:

Wouldn't it be cool if someone could come up with a really tiny side
scanning radar system that would work on these little machines. All you'd
need to do is runa a single pass across the part from above and the
sensor(s) would be able to detect all the minute variations of the part.
Then all, you'd need is to covert the image into 3D, import it to Rhino or
something other program to build an .stl, .dxf or whatever file and then
send that to your software used for generating the gcode.

Smoke

>Good idea Smoke, I think an aperture
>system would be a good way of doing it.
>
>But it has occured to me that nobody
>really got what I meant by optos.
>Imagine the optos that are used to break
>a light beam when your x-travel gets to
>home position.
>
>But they don't have to be on/off light
>beams. Shine one at an angled or curved
>surface and it returns a analogue value
>in volts. ANY movement of the reflecting
>surface will cause the exact amount of
>light to change, up or down, giving a
>"hit".
>
>You don't need to make it so it measures
>the movement, just detects it. This is
>easy, the signal can be "zeroed" every
>time, then as the probe is lowered ANY
>change in signal from the opto(s) will
>give a "hit".
>
>
>
>
>--- In CAD_CAM_EDM_DRO@egroups.com, "Smoke" <Smoke@5...> wrote:
>> I think you might be able to use a gunsmithing/potography trick with
>those
>> opto set ups.
>>
>> First you mask (black out) the end of the pick up unit with some
>sort of
>> disk (or possibly a short length of "rod") glued in place. Put a
>VERY TINY
>> pinhole in the disk (rod) to allow light to come thru.
>>
>> Mount mirror on the end of the probe, with the probe free to move
>angularly
>> when it contacts a surface. With a small enough pinhole thru a thick
>enough
>> disk, the angular movement should be enough to block light return to
>the
>> opto unit. The probe would need to be free enough to move yet be
>able to
>> return to center position CONSISENTLY when the probe has been moved
>away
>> from contact with the part. It might be necessary to increase the
>movement
>> of the mirror by mounting it on the end of a "multiplier arm"
>between the
>> probe and the sensor rather than directly on the end of the probe.
>>
>> How much "adjusting" it would take remains to be seen.
>>
>> Smoke
>>
>>
>> -----Original Message-----
>> From: Ian Wright <Ian@i...>
>> To: CAD_CAM_EDM_DRO@egroups.com <CAD_CAM_EDM_DRO@egroups.com>
>> Date: Thursday, January 11, 2001 5:12 PM
>> Subject: Re: [CAD_CAM_EDM_DRO] Re: Digitizers, Renishaw
>>
>>
>> >Hi Jon,
>> >
>> >The only way you could get a similar accuracy using an opto set-up
>would be
>> >to make the disk very wide relative to the length of the probe and
>put tiny
>> >shutters at its periphery between LED/opto sensors. This would
>probably
>> work
>> >but, you would have a big problem in preventing the disk rotating
>whilst
>> >keeping the movement light enough.
>> >
>> >Ian
>> >--
>> >Ian W. Wright
>> >Sheffield UK
>> >www.iw63.freeserve.co.uk
>> >----- Original Message -----
>> >From: "Jon Elson" <jmelson@a...>
>> >To: <CAD_CAM_EDM_DRO@egroups.com>
>> >Sent: 11 January 2001 19:56
>> >Subject: Re: [CAD_CAM_EDM_DRO] Re: Digitizers, Renishaw
>> >
>> >
>> >>
>> >> Well, there's the rub. The Renishaw design causes an open
>> >> circuit when the contact probe is moved .0002" in ANY
>> >> direction. I can see how this will work with an electrical
>contact
>> >> between two hard, rigid parts. I can also see how bad contact
>> >> could occur, as you say.
>> >>
>> >> I don't see an easy way to make a low-force probe that will
>detect
>> >> such tiny motion in any direction by optical means.
>> >>
>> >> Renishaw obviously solved this problem, and have been making
>> >> these devices for many years.
>> >>
>> >> Jon
>> >>
>> >>
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>> >>
>> >>
>> >
>> >
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>
>
>Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for the

discussion of shop built systems, for CAD, CAM, EDM, and DRO.

>
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