Re: dual motors

--- In CAD_CAM_EDM_DRO@egroups.com, "Don Chandler" <chandler@n...>
wrote:

> <I want to use twin motors to drive my gantry at both ends and I

have

> <nightmares about how open loop control could put my machine in yoga
> <positions.
> I have a 4' X 8' router with two motors on the X axis and one

motor on the

> Y-axis. I never have a problem with them getting skewed. It will

run at 150

> in/min with no problem. A plasma requires no force at all, compared

to a

> router, since it is non contact with the work, so you should have

no problem

> at all. What you really should be worrying about is torch height

control.

> If you find a cheap, automatic, reliable way to do this, let know.

Welll...I want to make my machine adaptable to a router as well. I
agree with you on the torch height control. Torchmate has a stand
alone automatic torch height control (1695.00) that has its own micro
processor and stepper mechanism. I ran across an Australian company
on the internet (sorry the link is on one of my other machines) that
has torch height controls but they won't sell just one. They do have
an "evaluation" kit that runs 1400.00 US. They use the arc voltage as
feedback to adjust the height. I think the Torchmate control uses
proximity sensors. I have a whole box full of various proximity
sensors that I am tempted to play with. I shouldn't be too difficult
to build a closed loop circuit that would keep the torch at a
constant height above the work, but is that all that is required?
The PlasmaCam unit has Z axis control and lists that as an important
feature, but they are not specific about if it is based on some form
of surface feedback or just a raise and lower control from the
computer.

I downloaded a demo version of SuperCam and I have been trying to use
it...honest I have! BUT the last 8 years of using and becoming
proficient with Windows has ruined my tolerance for learning and
typing a bunch of commands. I am surprised that the technology is
closer to the G-code and DOS stuff I learned in 1978 than to the
modern systems of today. Don't get me wrong. I believe DOS is still
a good control language and is still used a lot in embedded systems,
but when humans have to interface with computer screens Mr. Gates
system is much more efficient. I understand that Windows is a poor
IO language and the OS eats a lot of the CPU overhead just running
but the slowest machine I can buy used is a 233Mhz box with 48M ram
and a 6 Gig HD. How about some real 32 bit drivers for some
controller cards that take over the step and direction and timing
issues? I know that a lot of the guys are just interested in making
chips (so am I) but I am also trying to figure out a way to "retire"
from working for someone else as an engineer and programmer and make
a living using CNC and modern computer graphics. The Linux thing
(EMC) is interesting and I am not adverse to using that OS but I
would like to see some of the program overhead moved to controller
cards. Woops, time to get down off my soapbox! The IMPORTANT thing
is that we are all exchanging ideas.