--- In
sheetcam@yahoogroups.com, "pfauto" <pfauto@...> wrote:
Tom Wrote "
In over four years of plasma cutting on my table with no far limits I
have never banged the top of my Z. Since I have a 6 inch stroke and
all my cutting is done in the first 1" of travel, nothing in my code
ever lifts it more than 1" above the reference height on Z (top of
material)."
Do you have Softlimits turned on on your machine?
Nope
Does anyone else ever run your machine?
Yes. In fact most of the jobs are now run by a couple of part timers
If so how do they know where the physical limits of the machine are
if you don't use softlimits?
I take them by the hand and show them the top of the rails and say
"Don't raise the head that far or an alarm will go off and you will
receive a painful shock" Since the Z is a stepper and there are hard
stops all it really does is just stall.
Since Sheetcam knows where the table limits are it won't write code
that will go past the stops so the only way it could happen is if an
operator jogs it all the way.
If I am concerned about safety and far limits I hook up separate
limits and make them turn off the power to the motors. That in fact
is a single connection in any of the controllers we build.
"We advise operators to manually reference each axis individually at
machine startup. (using the REF buttons we put next to each DRO) If
they really want to ref Z it needs to be with a piece of material on
the grid"
I agree homing at start up is very important!
"Since the very first move in the code using the SheetCAM THC post is
to move to the first pierce point and establish the top of material I
never worry about where Z "thinks" it is as long as I can look at the
table and determine it's some distance above the table."
Using it the way I do ,I push the Default RefAllButton,and my Z
moves up away from the table Ref's itself and then on to the other
Axis left
RefAllButton is a no-no in plasma cutting. The button is removed
(just like the Go Home button) from our screens. The custom button
that does the referencing is my "RefXY" button. We even put that in
our Hand controller as a button for the THC. It does not move the Z
on a reference move. On my router (that has no Z home switch) I just
have it lift the head 1" THEN ref XY.
The M03 when used finds the top of the plate.
"Soft limits are nice but they only work if you have them enabled in
MACH....yet another setting the operator has to confirm. They can get
turned off easily and then you have no software protection."
That's why I want to use them on my machine!
So the operator can forget and crash the machine thinking they are
protected? hummmmm.....
"Putting all of the parameters in MACH3 for pierce delay, Pierce
height, Cut height, etc that are normally embedded in the g-code by
SheetCAM forces the operator to check more things before the cut and
have a higher technical understanding of what all those parameters
mean. Heck, I sometimes forget to readjust my cut current after
switching material and tips ! There are enough parameters to check to
get a good cut without having to put in new values in DRO's."
I agree this is not a good idea either,What would be nice,if some
how SheetCam could set up the correct DRO's when a file is loaded then
the user could make a adjustment if needed,as the tips wear out or
whatever chanded the cut Quality,Or is this what scale in the post
processor does under mach does it overide the settings by a percentage?
None of the parameters involved except possibly feedrate (which you
can override while cutting), and the tip volts on the THC (which also
can be adjusted on the fly) have a lot of effect on cut quality.
Definitely not the pierce height, delay or initial cut height. Those
numbers should not be "messed" with by an unskilled operator. By the
time a tip wears out enough to cause problems with cut quality, you
better replace it because shortly you will hear a "snark" sound and
the machine starts gouging a trench in the top of the metal with no
penetration. Then you have to stop the machine. Replace consummables,
possibly re-reference the XY and then crawl back through the G-code
and restart the cut (and turn off the THC in MACH so the tip won't
dive into the existing kerf!)
"As one of the primary support persons for the THC300 and MP1000-THC
units I will openly state that anyone that wants to use Erik's custom
macro needs to direct any support issues to him."
As I stated I din't want to send this to the group ,It was intended
for only Les to get it,I'm not here trying to promote anyone to use my
approach.
I know what would solve all these problems if Mach3 when using the
G28.1 ,there was Check Box ,under General Config,to set the G28.1
Probe direction,seems all my issues would go away ,There is a checkBox
for G28.1 No Intial Move,but I didn't find any reading meterial on it
in the manual or a good search on the forum I'm sure it is there
somewhere in the forum's burried in posts.
Hope I get this all fixed soon,I need to ship this machine,at least
now I have two ways they can choose to run the machine the way they want.
Thanks Erik
With all due respect the machine could have been shipped 2 weeks ago
if the time spent re-engineering a process that already works was
instead focused on building the machine and not writing a bunch of
custom macros and modifying the posts.
Most shops don't hire Rhodes Scholars to run a dirty smokey plasma
cutter. The more variables you hand them, the more they will try, and
the more often your phone will ring. So instead of changing a tip
when it starts to show signs of wear, they will try to get more time
from a worn tip and dink with adjustments. I have considered removing
the Feedrate override on some installs just to eliminate one more
variable (:-o