Re: [CAD_CAM_EDM_DRO] Udated DRO

Hi All
Re Cable Encoder Drives.

I have used a system I first saw used on a Texas Instruments chart
recorder, which had a smallish drum with about a 1 millimetre pitch
"thread" on the outside. The wire lay in this, and was attached at one
point. This removed the possibility of any slip, and as the wire is
constrained into the thread it does not "screw" or bunch. I have done
this in various ways - one of the easiest was a DC motor from an H.P.
printer carriage with encoder on the back, use the encoder as the read out
source, and apply a constant DC voltage and current to the stalled motor to
maintain the wire tension. You can get enough tension from a current which
does not worry the motor in the stalled condition.

Jim Gregg

At 08:53 PM 7/6/00 +0000, you wrote:

>Art,
>
>OK, the cable does a 180degree wrap around the 5mm encoder shaft, right?
>Did you groove the encoder shaft to keep the cable in one place on the
>shaft. The picture of the encoder shaft on your web site is too small to
>tell. It seems the cable might slip going around such a small diameter.
>
>I have a half dozen of the motor/encoder units from E. Goldmine and I'd
>like to make a dro for lathes. The cable idea might work well on the bed
>travel.
>
>Bob