Unless this was going to be a special purpose machine, I don't think I would
close the loop with a PID. I would just use straight probing G38.2 with a
subroutine that did a raster scan. It wouldn't be as neat or as smooth (nor
nearly as fast), but would probably do the job just fine.
Ken
[EMAIL PROTECTED]
Mark Kenny Products Company, LLC
55 Main Street Voice: (203)426-7166
Newtown, CT 06470 Fax: (203)426-9138
http://www.MarkKenny.com
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Alex Joni
Sent: Sunday, January 28, 2007 4:41 AM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Is there an easy way to workwithanirregular
surface?
This sounds very similar to the plasma Torch Height Control.
On plasma cutting the arc voltage is monitored in order to keep the
distance constant.
I would use an analogue/inductive/capacitive Probe (as Ken suggested), and
set up a PID to keep position using HAL.
It would be very similar to the example in the wiki:
http://wiki.linuxcnc.org/cgi-bin/emcinfo.pl?Torch_Height_Control
As for G-code I suppose you could use normal G-code, and maybe 1-2 custom
M codes to turn on/off the tracking at the right height.
Best regards,
Alex
----- Original Message -----
From: Michael Dubno
To: Enhanced Machine Controller (EMC)
Sent: Sunday, January 28, 2007 4:30 AM
Subject: Re: [Emc-users] Is there an easy way to work withanirregular
surface?
Any idea of what the G code would look like?
----------------------------------------------------------------------------
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Kenneth Lerman
Sent: Saturday, January 27, 2007 9:30 PM
To: Enhanced Machine Controller (EMC)
Subject: Re: [Emc-users] Is there an easy way to work with anirregular
surface?
I once used a device that added a hydraulic knee to a bridgeport. A
probe mounted on an arm actuated it. When moving the table in X and Y, the
probe caused the knee to raise and lower so as to keep the probe in contact
with the surface of the object. This, in turn, caused the cutter to cut the
stock to the proper depth.
That was around forty years ago.
If you mounted an electrical probe parallel to the head in that way, you
could do the same thing with EMC. The state of the probing command in EMC2
is uncertain, though.
Ken
[EMAIL PROTECTED]
Mark Kenny Products Company, LLC
55 Main Street Voice: (203)426-7166
Newtown, CT 06470 Fax: (203)426-9138
http://www.MarkKenny.com
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] Behalf Of Michael Dubno
Sent: Saturday, January 27, 2007 6:32 PM
To: [email protected]
Subject: [Emc-users] Is there an easy way to work with an irregular
surface?
I would like to automate the cutting of objects found in nature that
are roughly spherical and vary in radius. What seems to make sense is to
issue a G code command to make the cutting head move until a limit switch is
triggered on the surface of the object; disable the limit switch; use
relative motion commands; repeat. Has anyone encountered anything like
this? Is there a way to do what Im attempting without scanning the entire
object first?
Thanks - Mike
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