开云体育

Robert N. Ash wrote:

Thanks to someone for starting the list, I referenced it from the CNC
machines NG. Already see some published names I am familiar with and the
info is more relative to my use. I have a MAXNC motion kit and have used
it on one homebuilt machine. I salvage electronics from copiers and
other electro-mechanicals for my projects.(poor) I am hoping to build a
larger CNC table router and some pick and place stuff in the future. Most
of my experience has been stepper use though I have several brushless 3
phase motors with controllers. I have some progress pages started and
look forward to an FAQ.
My day job involves manual machine and other details for a development
lab.
Robert N Ash

-----Original Message-----
From: Tom Kulaga [mailto:tkulaga@...]
Sent: Friday, May 21, 1999 12:00 AM
To: CAD_CAM_EDM_DRO@...
Subject: [CAD_CAM_EDM_DRO] DRO card and future projects


From: Tom Kulaga <tkulaga@...>

I guess you've all seen the posts about the DRO card I built. I've
got an update to the software, adding metric support, cleaning up a
few things I didn't like, and changing the 4th axis to display in
degrees instead of linear units. I haven't posted it to the webpage
yet because I wanted to add backlash compensation first. That's the
problem.

The big drawback of backlash compensation is that you are forced to
make sure that all of the slop is cranked to one side of the travel
before you can zero that axis. If you don't, the computer doesn't
know where you are inside the backlash zone, and you can't trust the
numbers on the display.

My question is this: Do those of you who want to use rotary encoders
have a problem with this? Keep in mind, you won't be able to zero
the axis until you are certain that you've moved all the way to the
left or the right of the slop. I can think of more than one occasion
where this would be *really* annoying, but usually it would just be a
matter of getting in the habit of watching what you're doing a bit
more so than normal.

So, did I get that across clear enough? Is it worth it to add this
feature? I don't want to spend a whole bunch of time working on a
feature that nobody will want to use, especially since I've got a new
project I want to start.

Speaking of that new project, I've been following the comments about
the EMC software (gotta love the free stuff ;) with interest, and got
to thinking about how I'd go about trying it out here at home. I was
thinking that buying a motion control card is pretty pricey, and that
my DRO card makes a great jumping-off point for bigger and better
things. With a little extra work, and probably an extra 200 bucks, I
could come up with a 3-axis servo controller card design. It's a
little more involved, but using PWM for the output signal cleans it up
nicely, bringing it into the 'definately doable' range, even for
beginners.

I think that this group could easily write plans to build the card,
the servo amps, and the guidance you'd need to assemble the lot into
a really good webpage. I can handle the card OK, but I need to know
how the card interfaces with the EMC stuff, or if I could provide all
the register-level programming info to somebody who could write a
driver or whatever is needed to get things going. I don't yet have
Linux here at home, so I can't really experiment much. If there's
interest in this, I'll order Redhat next month.

What do you say, guys? Sound like fun?

-Tom Kulaga



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From: "Ian W. Wright" <Ian@...>



Dan Mauch wrote:

The z axis is set in a setup file because if you wanted mulitple passes

achieve the depth that you wanted you would be stuck if it imported the z
depths or you would have to edit them.

Thanks to those who replied - I'm gradually beginning to wipe the mud
from the window into this world of CNC! Of course, Dan's explanation of
why you can't just produce a 'Z' axis code automatically makes a lot of
sense when you think of it *but* I now have the problem of trying to
understand how this works if you are trying to cut a rounded 'hump'. I
saw a web site somewhere with a pretty picture of a blue car body on it
- is the perpetrator of that on the list and would he/she be prepared to
comment please?

Best wishes

Ian

--

Ian W. Wright LBHI
Sheffield Branch Chairman of the British Horological Institute.
Bandmaster and Euphonium player of the Hathersage Brass Band. UK.
See our homepage at:- or


'Music is the filling of regular time intervals with harmonious
oscillations.'

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From: Steve Gunsel <gunsel@...>

Tom,

I am definitely interested. I noticed that US Digital also offers
linear encoders for $2 per inch, which sounds reasonable. Of course
the electronic "readers" are extra, but the cost should be about the
same as for as a rotary (I presume!). Wouldn't this help address
backlash? At least you should be able to tell where you actually are.
I'm not sure how the slop effect when changing directions - not likely
to be good. But wouldn't this be a problem even with backlash
compensation?

Steve

At 10:02 PM 5/21/99 -0700, you wrote:

From: Tom Kulaga <tkulaga@...>

I guess you've all seen the posts about the DRO card I built. I've
got an update to the software, adding metric support, cleaning up a
few things I didn't like, and changing the 4th axis to display in
degrees instead of linear units. I haven't posted it to the webpage
yet because I wanted to add backlash compensation first. That's the
problem.

The big drawback of backlash compensation is that you are forced to
make sure that all of the slop is cranked to one side of the travel
before you can zero that axis. If you don't, the computer doesn't
know where you are inside the backlash zone, and you can't trust the
numbers on the display.

My question is this: Do those of you who want to use rotary encoders
have a problem with this? Keep in mind, you won't be able to zero
the axis until you are certain that you've moved all the way to the
left or the right of the slop. I can think of more than one occasion
where this would be *really* annoying, but usually it would just be a
matter of getting in the habit of watching what you're doing a bit
more so than normal.

So, did I get that across clear enough? Is it worth it to add this
feature? I don't want to spend a whole bunch of time working on a
feature that nobody will want to use, especially since I've got a new
project I want to start.

Speaking of that new project, I've been following the comments about
the EMC software (gotta love the free stuff ;) with interest, and got
to thinking about how I'd go about trying it out here at home. I was
thinking that buying a motion control card is pretty pricey, and that
my DRO card makes a great jumping-off point for bigger and better
things. With a little extra work, and probably an extra 200 bucks, I
could come up with a 3-axis servo controller card design. It's a
little more involved, but using PWM for the output signal cleans it up
nicely, bringing it into the 'definately doable' range, even for
beginners.

I think that this group could easily write plans to build the card,
the servo amps, and the guidance you'd need to assemble the lot into
a really good webpage. I can handle the card OK, but I need to know
how the card interfaces with the EMC stuff, or if I could provide all
the register-level programming info to somebody who could write a
driver or whatever is needed to get things going. I don't yet have
Linux here at home, so I can't really experiment much. If there's
interest in this, I'll order Redhat next month.

What do you say, guys? Sound like fun?

-Tom Kulaga



------------------------------------------------------------------------
With more than 17 million e-mails exchanged daily...

...ONElist is THE place where the world talks!
------------------------------------------------------------------------
welcome to CAD_CAM_EDM_DRO@..., an unmodulated list for the

discussion of shop built systems in the above catagories.

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