Re: [CAD_CAM_EDM_DRO] Udated DRO

Bob,
No, the cable just rides on the shaft and is guided by the slot in the
encoder block. In theory, there should not be a tracking problem as you
"should" have all shafting parallel as well as all cabling. When I was
initially working on this, I tried using several wraps (like the old radio
dial), but the cable "screwed" on the shaft and therefore would not
maintain its parallel position relative to the bed.

I agree and have been concerned about the small diameter and lack of
friction. This is one of the reasons that I went to the 180 degree wrap.
However on the z axis, I did slot the shaft trying to get a smaller
diameter to increase resolution. If I remember correctly, I cut a groove
somewhere around .030-040" deep. So far, I do not appear to have to many
problems; however, I am also worried about shaft bending strength as I
approach 1/8" diameter. All kinds of trade-offs.

When I do the lathe, am going to hook the encoder to the lead screw for the
cross-slide. This will be done as I am worried about swarf in the cable
mech. and the space constraints.

Art

At 08:53 PM 7/6/00, 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
>
>At 05:23 PM 7/6/00 -0400, you wrote:
>>Bob,
>>No, I did not put a pulley on the encoder, but put a pair of pulleys in the
>>line to the encoder. See my web page at
>>
>>http//:www.surfsouth.com/~axtein/dro/dro1/index.html
>>

OLDER THAN DIRT

Country Bubba

(Actually the inventor of Country and Bubba)

axtein@...