Re: Which controller card for EMC? Ballscrew Class ?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "turbulatordude"
<dave_mucha@y...> wrote:

>
> Class 3 ballscrews ? didn't we just have a discussion about ball
> screws ? I don't remember anyone bringing in something like
> industrial gradeing systems or classes, but more on rolled vs.

ground.

>
> I think further reading is in order.
>
> Dave

I have done a lot of looking around and for what I can find
appropriate size and lead rolled ballscrews for, I can very patiently
await a rare find for some good precision ground ballscrews. I have
one Class 1 Kuroda ballscrew from eBay that I snapped up for about
$225 for a 14in travel, .200 lead, dual nut screw with end blocks and
bearings. If anyone knows where to find more accurate rolled screws,
I'm all ears. It's all about accuracy and price. I'm so far from
actually building at this point and working primarily on the layout
of stuff I already have, that I can be patient about the ballscrews.
Using Pro/E for a top down design, changing a spec or two here and
there really doesn't pose much of an issue if I have to gain or lose
an inch or two of travel here and there.

Using rolled ballscrews will definately achieve the level of accuracy
I am looking for if I were to use dual loop encoding (encoder fusion
as some call it) by using a linear encoder as well as a rotary
encoder on the servo itself. Programming the PID loop properly is a
bit more of a chore using EMC as nothing exists commercially for dual
loop feedback (yet.) So, if it is something I will be writing myself,
I would like to have the machine usable until the linear encoders are
mounted and the feedback software is complete.

To answer the previous questions about why I narrowed it down to the
two cards (STG2 or Vital), I am actually looking at a third, the
vigilant card as well. But again, these are not my only options, as
long as the card has a driver for EMC or vice versa.

My criteria were > 4 axes, EMC drivers pre-existing, and industry
standard +/- 10V signals to the servo amplifiers. Since eventually
tool changing will be added to the system, I wanted as much control
as possible given to the operating system and nc software. EMC/Linux
seems to me to provide the most open option, although I am always
open to input from others.

Jim