Re: Littlemachine Shop 3 axis DRO

I have one of the positron 3A head units. It does not have any
serial outputs on the head itself, just 3 ports that connect to the
scales. As for mounting the scales, It takes a bit of work to get
them correctly mounted because they have to run true with the
machine slides. The mounting blocks will have to be made to suit
your particular machine. On my setup , the scale head is fixed and
the scale is fastened to the milling table so the scale moves
through the head.On a lathe , the scale would be fixed to the bed
and the head would move along with the traverse.
I did not use the supplied brackets for the scales instead opting to
make more rugged mounting points. I also folded protective covers
for the scale out of thin steel plate to keep dust and swarf off the
scales.
I lubricate the stainless steel surfaces of the scale with a lighty
oiled rag. This also helps to remove any dust that might settle on
them.
One thing to note is that the Positron 3A head does not read the
scales and then display this reading on the 7 segment LED because
when I switch the unit on the scale could be reading 25mm but the
positron will read zero. Instead it seems to be using the scales as
a form of encoder. Pressing zero on the positron does not zero the
scales.
The single axis units that I own work differently. They read the
scales and display the same reading on the heads. Also pressing zero
on the head zeros the scale as well.


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Patrick J" <patrick@d...>
wrote:

> > Littlemachineshop.com
> > The Picture shows 3 Linar Scales built in China and a Digital

Readout

> Head.
> > I am looking for Doc's on the DRO head itself. (does it have a

serial

> > output to RS232 ?)
> http://www.littlemachineshop.com/products/product_view.php?

ProductID=2012

>
> I am also interested to find out more about it. Any drawings or

photos

> showing how to fasten the moving part to the moving object ? (ie

backside)

>
> And how fast can one read from it, and in what procol? RS232?
> (I need to read the position with a PIC MCU)
> Are they sensitive to oil, dust, vibrations?
>
> And that expensive cable.. wonder if there is any way to skip it :P
> if not.. one end seems to be a really special plug, and the other

one looks

> like a standart PS/2 computor mouse/keyb contact ?