Re: mounting encoder with pulley

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Alan Marconett <KM6VV@a...>
wrote:

> Hi Lance,
>
> You're saying that the pulse multiplier in the G340 both multiplies

the

> pulses from the CPU, AND divides the pulses coming in from the

encoder?

> I guess I missed that. I was under the impression that the

little

> board was only slightly different from the one in the G210, called

a

> G901. The notes for the G901 don't mention any divider for the

encoder.

>
> My servos are 300W Sanyo Denki "Super R". I haven't found any
> additional information on them, other then what's on the nameplate.
> Maybe I don't need any pulley reduction on them, they probably have
> considerable torque!
>
> I was planning on trying them out on the original leadscrews (20

TPI?)

> on my RF-31 mill (ugh!), before I can get ballscrews. Probably

means I

> need a LOT of steps!
>
> 8000 * 20 is 160,000 counts per inch.
> 60 IPM would need 160K steps/sec.
>
> Sounds like a Gecko G340 could handle that, but there were some

comments

> about positioning errors at high pulse rates (over 250K?). And I

don't

> think my old computers are up to that! If I do any belt reduction,

I'm out.

>
> Yeah, I want to play with some G340s!
>
> Alan KM6VV
>
>

Alan nothing is divided. The board in the 210 and 340 muiltiplies
the incomimg steps so your computer doesn't have to try and output
more than it can (normally 25 to 45,000 pps). It works like this.
send the multiplier card a pulse and depending in its setting it will
send 2, 5 or 10 pulses to the normal motor drive circuit. One pulse
in gets you multiple pulses out of the multiplier card. Since the
upper limit of the normal Gecko circuit is 250,000 pps from ANY
source (straight input or from the multiplier board) you could not,
for example, stuff 40,000 pps in with the multiplier set at X10 and
try to feed the base circuit 400,000pps second. The output of the
encoder has four distinct transitions per 'line' so if you have 2000
lines you get 8000 pulses per rev.

This combination is not very well matched. Kinda like putting 30"
tires on a shopping cart. You have way to high a line count on the
encoders and the 20 TPI screws are an added limiting factor. The good
news is you should not face any torque issues!