Re: Re: EMC interpreter was Re: BoBCad Question

Randy

From: cnc002@...

<S>In this case the radius compensation doesn't present a big problem as

>that feature on the old A-B controls of this customer never worked
>properly anyway and they just do the toolpath in BobCad.

<rant>
I have real problems with both the generalization about AB and the
generation of tool comp in a cad program. 1- AB always seemed to do
adequate tool comp for the operators I know and the machines I own. (emc
does good comp if you treat it right). 2- Comp built into a program is okay
but what happens when your operators have to replace the end mill at
midnight and the cad operator isn't around. Perhaps what you were seeing
was a user problem rather than an AB control problem.

>I know that EMC is supposed to support servo control but have
>heard that is doesn't work very well.

You must be listening to competitors or idiots!

>I have downloaded a copy of EMC and am working on a prototype control
>using it to see what features are really there and if a true servo, closed
>loop system can be developed around it.

Good. Perhpas you will detail the nature of your test bed along with your
results.

Jon E. has been using such a system with the EMC for more than 18 months.
He uses the servo to go board on his system so that the loop is closed in
the EMC pc itself rather than in some outboard device. His new EPP board
at names ran a closed loop servo just fine. If there were any problems
with the EMC and closed loop motion, my guess is that he would have been
the first to say it.

I also saw Bert in Endhoven do some precision stuff with EMC and closed loop
servos that I had thought was impossible. Closed loop servo motion was the
heart of the EMC from the very start of the project.

>Please keep in mind that I am fairly new to the PC based generic
>controller.

Okay! I've got no problem with a newbie to a technology, I am myself
about once a month. And I've got no problem with folk choosing to apply
or become dealers for different technology than I apply or deal. But if
it was me, I'd post stuff like this as questions rather than as absurd
statements. Perhaps something like, "I've heard that AB had some problems
with tool diameter comp?" Or, "Anyone have experience with using the EMC
to drive closed loop servos? I've heard it can't."

There are folk a lot more qualified than you or I will ever be who are
testing the EMC motion API in govt and industry sponsored labs around the
world. Ocasionally we see suggestions from these folk about improving
that code.

</rant>
<flamesuit>

Ray