Re: [CAD_CAM_EDM_DRO] encoders and table position

On Friday 06 June 2003 01:06 am, Jon Elson spake:

> Weyland wrote:
> >Okay, having looked into it a bit more, it doesn't look like the linear
> >scales I have are going to work with the Kaluga/Mauch DRO board after all.
>
> Why won't they work? Are they analog scales? You can get the basic
> resolution of the scales pretty easily, but that might be too coarse.
> As long as they provide some sort of quadrature signal, it should be
> relatively simple to interface them.

Well, for a few reasons as I understand (or not).
First is that no one seems to be able to tell me with certainty what the wires
do, and as far as I've found in my searches, there isn't any standard to the
color coding of the wires.
Second, is that it seems I have a few different
configurations, two are six pin connector, and one is nine pin.

Now, in taking the six pin apart, I did find that they are actually only using
five wires, but again they are coded differently, and I've not the knowledge
nor equipment to figure it out I think.

> >My reservation against using the itty-bitty QEDS units I have
> >is that they measure screw movement and not table position.
>
> Yes, if your screw is of low quality, then anything read out by an
> encoder on that screw will be no better.

Exactly my feelings...
I am considering heavily the option of ballscrews and nuts at this point, but
I'm still thinking I want my positioning done by table, not screw position.

(Besides the fact that it's starting to look like I'm trying
to make a silk purse from a sow's ear. This *IS* an older
benchtop mill. Still I've got to start *somewhere*...)

> >Has anyone come across a *relatively* inexpensive solution to
> >constructing linear encoders for use with the K&M board & EMC?
>
> There are some schemes for using rollers or wires to turn shaft encoders
> with linear motion of the machine. These have been discussed in great
> detail in past threads.

I saw that, thanks.
I'm not sure I'm partial to the idea, and was more wondering if anyone
had come across a relatively inexpensive solution to linear encoders.

From what I can tell, one could buy a linear strip and
reader head for *relatively* small dollars, but I'm trying
to think of just how I would mount the strips.

For that matter, is it possible that I might be able to simply buy
the reader heads and use them with the scales I've already got?
At $25.00 each from US Digital, it makes
a very reasonable solution to this problem.

Or am I missing something here?

Thanks for replying and any further suggestions.

Best,

Weyland