Re: Encoder recommendations

I've got HP/Agilent HEDS-5505-A06 that are testing out fine. They are
within the Gecko encoder current supply limits, and the A06 specifies
1/4" thru shaft. There is an index variation that makes is possible to
get a home location to a small fraction of a motor rotation, instead
of by just a home microswitch. My HP's don't have the index, but I may
piggyback an rotational index on if my homes don't come out as
repeatable as I'd like.

The caution about step rate and encoder resolution is a good one. I
have 500 CPR, and with a 40K step / sec output, my rapids calculate to
~88 in/min. Your results depend on the motor volts / 1000 RPM spec. I
can email you a nice little machine setup calculator if you need it.

Linear encoders, definitely stay away.


--- In CAD_CAM_EDM_DRO@yahoogroups.com, "A. G. Eckstein"
<a_eckstein@b...> wrote:

> US Digital encoders are great for Geckos [you do not want or need the
> differential output due to the current draw], but you need to look

at the

> tradeoffs of how much resolution you will need vs the speed at which

you

> will get it!
>
> In my case, I mounted 500 line encoders on the ball screw and get

0.0001

> resolution! With my current setup, this allows rapids on the order

of 90 IPM.

> If I were to go to lets say 2000 line encoders, my resolution goes to
> 0.000025", BUT do to the speed of my computer, I have to slow down

things

> and only get 38~ IPM
>
> As for using linears, UNLESS you have ABSOLUTELY NO BACKLASH, the table
> will sit there and oscillate and maybe even violently! Been there

tried

> that when I switched from DRO to CNC.
>
> Also last time I checked, the max you could get is 500 line which
> translates into 0.0005" and will this be enough resolution for you??
>
> Just some thoughts.
>
> Bubba
>
>
> At 11:24 AM 10/29/2004, you wrote:
>
>
> >I just got a great deal on ebay for 3 servo motors. :-)
> >
> >Problem was, all of the encoders were broken.:-(
> >
> >I now have to replace them but was wondering what was recommended. I
> >am using gecko 320's with Mach2 and would like the highest
> >resolution. Motors are 4000 rpm no load and will be running about
> >1000 rpm when on the machine. Back of shaft is 1/4" and 3/4" long. I
> >would like to use US Digital since I'm familiar with them.
> >
> >How about linear feedback instead?
> >
> >
> >
> >
>
> Bubba
>
> OLDER THAN DIRT
> Country Bubba
> (Actually the inventor of Country and Bubba)
> In God We Trust
>
> LaGrange, GA
>
> http://bellsouthpwp.net/A/r/Arts_home_page/cnc/
>
> [Non-text portions of this message have been removed]