re:Re: Re: 3D Scanner/ Dizitizer

re a z-axis probe:
I used (about 1977) a measuring machine made from a Moore jig borer. The
part was probed in z with a sapphire ball mounted in an air bearing and
counterweighted to a controlled pressure. It was lifted up and lowered
gently to the surface, the z axis of the jig borer was rarely used. z
distance was measured with an interferometer to 1 x 10^-6 inch.
This concept might be a good way of adapting a mill to coordinate
measurements, make an auxillary z axis which moves quickly and with little
or no friction. No particular stiffness is needed, as the measurements can
be made while the machine is stationary. There are scales made without
seals that would have zero friction, or you can take apart a cheap
electronic caliper to do the same thing (no friction).

regards-
Elliot B.


Date: Sun, 18 Apr 2004 17:22:48 -0500
From: Harvey White <madyn@...>
Subject: Re: Re: 3D Scanner/ Dizitizer

On Sun, 18 Apr 2004 19:53:36 -0000, you wrote:

>Hi,
>
>I have been looking at ways to speed up digitizing, as using a a
>probe is so slow and really wears out the z axis if you are doing a
>lot of deep or large objects.
>
>I have hand held laser measuring equipment which Might do, it costs
>around £250 uk pounds.
>
>I have taken it to peices and was wondering if anybody on this site
>would now how to tap into the information that is sent up a flat
>ribbon conector to lcd digital readout. If this can be done it would
>be easy to divert the signals to the pc witha simple connector.

If the LCD has the standard two controllers on it, you will find that
the device acts like a memory location.

It will probably have either 4 or 8 data lines, a read strobe, a write
strobe (or a R/W- line) and a select line. The select line must be
down for the data to be available.

Paralleling something like a 74HCT374 across the data lines, then
adding another latch that records the state of the R/W- line, and then
activating that with the R or W strobe should be fine.

You'd need the exact manufacturer's data on what lines are what, but
that would do nicely.

You'd end up with a few flipflops and probably a little programming in
a microprocessor, or perhaps just a little programming in a
microprocessor.

Harvey


>
>I will attempt to post some pictures in the photos section.
>
>Thanks
>
>Remo.
>
>
>
>
>--- In CAD_CAM_EDM_DRO@yahoogroups.com, "ruanb1" <rrbasson@t...>
>wrote:
>> Hi Guys
>>
>> Just an idea, I am thinking off. It sure would be nice to be able
>to
>> have a scanning system (affordable) without the contact like the
>> probes.
>>
>> I was thinking: Can one not use the distance sensors (which is
>> cheap) mounted on the axes to fulfill this, I mean we basically
>> would just like distances, and with software then create the
>> models???
>>
>> Have any of you thought in this line or build something like this
>on
>> your CNC machines?
>>
>> It surely would not break the bank (although it might be hell of
>> slow scanning).
>>
>> Would appreciate your ideas
>>
>> Regards
>>
>> Ruan
>
>
>

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