Re: [CAD_CAM_EDM_DRO] glass scale alignment

Denis Casserly wrote:

>The read head looks like it rides on white (teflon?) pads and I guess that
>they have to ride on some sort of reference track inside the extrusion which
>holds the scale - right?
>

Some have the teflon pads ride on the GLASS, which is a lot more wear
resistant
than the aluminum. And the ones with the tiny bearings have them ride
on the
aluminum. But, I guess they could have sliders thet run on the
aluminum, too.

> If that's the case I'll try to find that track that
>the pads ride on. The alignment looks like it a set of 4 grub screws and 2
>large clamp screws in an intermediate plate between the read head and the
>read head mounting bracket on the travelling axis. The adjustment setup looks
>like it will rock the head around relative to the scale.
>
>
>>The analyzer grating in the read head needs to be VERY close to the
>>scale, on the side with
>>
>>
>Yes, I can get it the read head to output by detaching it's mount, moving it
>around until I can get a reading, and moving it up and down the scale after I
>get the relatonship correct. So I think the head will read and it's an
>alignment issue between the head and the glass scale.
>
>

Yes, the "azimuth" alignment between the head and scale can be critical,
and it can get
knocked out of adjustment by rough handling.

>I've never heard of the manufacturer before, the only information that I can
>get off the scale is: ' METRIC 01 MM ' . Other than that there's nothing else
>on the scale or the read head. Here's the nameplate data off the Anilam DRO
> Model # 102-2, Serial # MW8121671, is that of any more help?
>

Oh, if it is used with an Anilam readout, it is very likely to be an
Anilam scale, too.

> I'll try to
>locate the spot where the teflon pads contact, the wire or track that you
>referred to earlier, perhaps it is broken and the read head can't get to the
>location where it will read the glass and output reliable data. Is it
>possible that the reference track is a tiny wire rope that's pulled taut
>inside the extrusion. I think that there was one hanging off the machine from
>the vicinity of the glass scale.
>
>

If the link between the external moving part and the head itself is
bent, it may prevent the
head from hugging the scale as it needs to when everything is
assembled. Some scales
use the springiness of the link to provide the force to hold the head
against the scale.

I can't imagine a wire rope being used here. I wonder if that was a
ground braid for
the signal cable? The scales I've had apart used either a piece of
spring steel about
1/4" wide or a stiff piece of music wire to drive the read head. This
piece is either
in tension or compression, depending on which way you are moving the
read head.
There may also be a spring of some type that provides the force to keep
the head
against the glass slide (and on the track it needs to follow in the spar.)


Jon