Re: [CAD_CAM_EDM_DRO] Bridgeport Textron DRO

jackw19x wrote:

>I'm trying to make my swap meet Bridgeport/Textron DRO work (linear
>glass scales); maybe someone has an idea.
>
>1) The display lights up and reads 0.0000 on both axes.
>
>2) When I move the read heads on the scales nothing happens, although
>once one axis did change to 0.0005 for a few seconds.
>
>3) I can't see any light coming from the read head LED's--but maybe
>they're infrared, etc.
>
>

Yes, very common for the older scales to use IR.

>4) Maybe the read heads have to be carefully aligned a la the
>installation manual in order to do their work? I haven't wanted to
>actually install the scales until I knew they worked.
>
>

Possible, but most scales, if they haven't been fouled up internally,
will still work off
the machine, if moved carefully. If moved roughly, the read head can
jump off whatever
track they are supposed to run on. I'd (carefully) open them up -
sounds like you've already
done that - and make sure the head is riding on whatever serves as a
track. The "analyzer"
grating needs to be REAL close to the main scale, but if it touches, it
will destroy either
the analyzer, the main scale, or both.

>5) The dust strips are off the scales--maybe light contamination is
>the problem?
>
>

It could be, but they should work in normal room light as long a a big
fluorescent lamp
isn't shining DIRECTLY into the works.

>I was able to get the install manual from B'port--but there are no
>pinouts or descriptions of what kind of signals the scales should
>send to the box or what brand of power the box should supply to the
>scales. If someone knows these parameters or has a service manual
>gathering dust, let's make a deal.
>
>

The older scales were mostly analog, and so you had varying voltages
that changed roughly like
sine waves as the stripes passed each other. Are these pure inch scales
or metric scales with
inch conversion in the readout?

Have you cleaned the scale? How about the analyzer gratings in the read
head? If these are
as old as I think they may be, the IR LEDs may have lost enough light
output that the
photocell adjustments need to be re-set. It would be much easier to do
that with an
oscilloscope, but a DVM could be used. Are there a bunch of TINY pots
on the read
head?

Jon