RE: [CAD_CAM_EDM_DRO] EMC step rate configuration

Let me figure now what is different between your system and a pseudo system.
Drives, motion card, tachs. All the rest of the parts are the same. Lets
figure the price now
Your servos $200 per axis
Motion card $880
tachs $15 each is you scrounge well.
Total $1525

pseudo system
drivers $100 each
Total $300

Yep, your should certainly be do something extra for the $$$

Point is, we are talking a totally different price range. Considering the
bang for the buck it is VERY hard to find fault with the Gecko system and
for many people on his list will perform just as well as your true servo at
a price they can afford. OK, so you need to be careful in selecting the
encoder count or just spend an extra $30 per drive and get the version that
will pulse multiply so it is not an issue.

Tim
[Denver, CO]

>
> John Murphy wrote:
>
> > I'm finishing up my grizzly/EMC conversion... How cool it feels when
> > you
> > jog your first axis!
> >
> > Now I'm thinking I've made a big design mistake: I used some surplus
> > motors
> > with pretty high resolution encoders, which I'm driving with the
> > wonderful gecko G320's, and are coupled to 10 TPI acme screws
> > with 2:1 reductions. Working through the math, I end up with
> > MANY MANY (Way too many!) steps per inch. Way more than I
> > can use... (like 100000+ steps per inch)
> >
> > Configuring EMC, I'm finding the relationship between MAX_VELOCITY
> > and INPUT_SCALE to limit my max speed. I'm using the default
> > PERIOD, etc setting in EMC on a K6-266. Obviously, if I set
> > the velocity too high, EMC hangs during startup, since I've
> > set things faster than the pulses could be output.
> >
> > Short of changing encoders/motors (which I've done temporarily on
> > my Z axis, just to get a tolerable speed for tool changes), what are
> > my options? I don't care about speed while I'm machining much (it's
> > not a production type machine for obvious reasons), but jogging, etc
> > is slow.
>
> Well, this is the problem you run into with a pseudo-servo system!
> I have a real servo system, and am running with 20,000 encoder counts
> per inch on X and Y, and 40,000 counts/in on Z, and it is no limit at all,
> even on a 100 MHz Pentium classic! I have my limits set at 120 IPM,
> but that is limited more by my motors and servo amps than EMC.
> EMC would have no problem going much faster. It only has to
> make a position/velocity update 1000 times a second.
>
> Jon
>
>
> Welcome to CAD_CAM_EDM_DRO@...,an unmoderated list for
> the discussion of shop built systems, for CAD, CAM, EDM, and DRO.
>
> Addresses:
> Post message: CAD_CAM_EDM_DRO@egroups.com
> Subscribe: CAD_CAM_EDM_DRO-subscribe@egroups.com
> Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@egroups.com
> List owner: CAD_CAM_EDM_DRO-owner@egroups.com, wanliker@...
> Moderator: jmelson@... [Moderator]
> URL to this page: http://www.egroups.com/group/CAD_CAM_EDM_DRO
> FAQ: http://www.ktmarketing.com/faq.html
> bill,
> List Manager
>
>